@conference {3672, title = {Assessing the meat quality of venison short-loin from farmed red deer using visible-near infrared spectroscopy}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {17-22}, address = {Napier}, abstract = {Venison from red deer (Cervus elaphus) is marketed as a premium quality, healthy red meat. Ideally, meat-quality attributes need to be measured prior to sale. Near infrared spectroscopy (NIRS) has potential for the measurement of sensory, nutritional and technological parameters in beef, but its use on venison has not yet been considered. The aim was to evaluate NIRS for predicting Warner-Bratzler shear-force parameters, meat colour, ultimate pH, sarcomere length and water holding capacity of venison short-loins. Samples were halved, vacuum packaged, aged for either 3 or 42 d at 1{\textpm}1{\textdegree}C and frozen, then defrosted for meat-quality assessment and acquisition of spectral data. In total, 154 samples (3 and 42 d aged) were divided into calibration (75\%) and validation datasets (25\%). Using partial-least squares regression, calibration equations were tested on the validation dataset. Prediction accuracies ranged from R2 =8.3\%, (SEpred =2.42) for meat lightness to R2 =66.6\%, (SEpred =0.10) for ultimate pH, suggesting that NIRS maybe useful for predicting some venison quality parameters.}, issn = {1176-5283}, author = {Craigie CR and Purchas RW and Maltin CA and Roehe R and Morris ST} } @conference {69519, title = {Effect of lipid type, selenium and vitamin E on total tract nutrient digestibility in growing pigs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {266-268}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {It has been shown that the fatty acid, selenium and vitamin E content of pork can be modified by dietary inclusion of different types of fat and/or supplementation with selenium and vitamin E (Morel et al.,2008). These dietary manipulations result in pork with an enhanced nutritive value. It is generally assumed that fat digestibility increases as the ratio of unsaturated to saturated fatty acids increases (Wiseman et al.,1998). However, it is not well documented how the addition of dietary antioxidants like selenium and vitamin E will affect nutrient digestibility.}, issn = {1176-5283}, author = {Nuijten WGM and Morel PCH and Purchas RW} } @conference {69518, title = {Review of pork-quality studies in New Zealand}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {261-265}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {This paper presents data published between 1990 and 2009 on pork quality in New Zealand. The characteristics considered are pale, soft and exudative (PSE), dark firm and dry (DFD), boar taint, intramuscular fat (IMF\%), chemical composition aspects such as fatty acids profile and flavours other than boar taint. Over the years the incidence of PSE has been reduced from 40\% to 6\%. The percentage of DFD pork was always below 7\%. A level of 2.0\% of IMF\% is considered as a minimum with respect to palatability. Between 1990 and 2009, reported values for IMF\% ranged from 0.98\% to 3.36\% and tended to decreased over time. Skatole and androstenone are the two major compounds responsible for boar taint. In New Zealand, males are slaughtered {\textquotedblleft}entire{\textquotedblright}. In 1996 only 19\% of them were below the European Community threshold for boar taint. Results from different feeding experiments show that the fatty acid profile, selenium content and flavours other than boar taint, of pork can easily be changed. Overall pork from New Zealand pigs is of a high quality, but the incidence of boar taint is of concern.}, issn = {1176-5283}, author = {Morel PCH and Purchas RW and Wilkinson BHP} } @conference {41694, title = {A comparison of carcass characteristics and meat quality for Angus, Hereford x Friesian, and Jersey x Friesian steers}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {67}, year = {2007}, month = {Jan}, pages = {18-22}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Wanaka}, abstract = {The aims of the two trials described here were to compare carcass characteristics and meat quality of Jersey-Friesian cross steers (Je x Fr) with Hereford-Friesian cross steers (He x Fr) and purebred Angus steers. Trial 1, which compared rising 3-year-old He x Fr with Je x Fr steers (20/grp), showed that the Je x Fr group had lighter carcass weights (93\%; P<0.001), yellower fat, slightly lower weight-adjusted dressing-out percentages (P<0.01), heavier weight-adjusted livers (P<0.01), and longer carcasses at the same weight (P<0.001). In Trial 2, 27-month Je x Fr steers (n=15) were compared with He x Fr (n=15) and Angus steers (n=14). Differences similar to those for Trial 1 were shown, and in addition the Je x Fr steers had lower fat depths and a lower yield of several cuts from the round.For both trials the Je x Fr group had a more mature pattern of incisor teeth eruption. For Trial 2 the quality of meat from the longissimus muscle did not differ between groups for ultimate pH, intramuscular fat level, colour, Warner-Bratzler shear force, or waterholding capacity. Sensory analysis by a trained panel revealed no differences in tenderness, flavour, or juiciness, in contrast to some other reports where beef from Jersey or Jersey-cross cattle has been favoured. These results indicate that the Je x Fr steers in these trials offered no advantages relative to He x Fr or Angus cattle, but they did show some minor disadvantages. These results, however, need to be considered alongside other reports indicating that Jersey or Jersey-cross steers will sometimes yield beef with advantages in levels of marbling fat and palatability.}, issn = {1176-5283}, author = {Purchas RW and Morris ST} } @conference {41827, title = {Effect of slaughter group and sire on carcass composition and meat quality characteristics of Texel-sired lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {65}, year = {2005}, month = {Jan}, pages = {241-246}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {New Zealand meat companies are investigating lamb payment systems based on lean-meat yield and meat quality. Factors that affect these traits need to be determined. Carcass composition and meat quality data from 450 Texel-cross lambs (ewe and ram) were used to evaluate the effect of sire (two sires Property One, three sires Property Two) and slaughter group. Lambs reaching target slaughter weight first (38 kg and 35 kg for ram and ewe lambs respectively) were allocated to slaughter group one, with the remainder allocated to slaughter group two and slaughtered approximately 40 days later. The average carcass weight for both groups was 17.9 {\textpm} 1.51 kg. Carcass composition traits were adjusted for carcass weight, and meat quality traits were adjusted for pH. Carcass width at the thorax and gigot was narrower in slaughter group two (P < 0.001). Trimmed leg weight and total leg muscle weight were lower (P < 0.001), whereas total leg fat weight and muscle to bone ratios were higher (P < 0.001), for slaughter group two. Femur muscularity was higher in slaughter group two (P < 0.001) for Property One only. Warner-Bratzler shear values and measures of colour (L*, a* and b*) were higher (P < 0.001), whereas cooking loss was lower (P < 0.001), for the longissimus muscle in slaughter group two. In addition, sire within property was a source of variation (P < 0.001) for all carcass composition traits and meat quality traits, with the exception of pH. These results demonstrate that both slaughter group and sire (within a breed and property) are significant sources of variation in carcass composition and meat quality traits. As a result, these need to be taken into account when making management and breeding decisions for the supply of lambs to meat companies under any future payment systems based on yield and meat quality. KEYWORDS: lamb; carcass traits; sire. }, issn = {1176-5283}, author = {PL Johnson and Purchas RW and Blair HT} } @conference {41831, title = {Relationships between on-farm and pre-slaughter behaviour and growth and meat quality for bulls and steers}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {65}, year = {2005}, month = {Jan}, pages = {261-265}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Angus and Hereford-Angus cross bulls (n = 58) and steers (n = 59) were assessed for temperament 3 times during post-weaning growth and for behaviour during pre-slaughter holding in order to investigate relationships between these traits and measures of growth and meat quality including meat tenderness and meat colour. Composite on-farm temperament scores encompassed measures during weighing of stepping and unease on the scale, and speed of movement and level of agitation when released from the scale. Pre-slaughter assessments included counts of butting, pushing, fighting and mounting. Plasma levels of cortisol, glucose, lactate and fatty acids at slaughter were measured. On-farm temperament scores were significantly correlated (P < 0.0001) between the 3 times and between measures within a time. On-farm measures, however, were not related to pre-slaughter scores or to plasma cortisol or metabolite levels. Plasma cortisol levels were significantly higher for steers than bulls (43.8 vs 22.4 ng/ml; P < 0.001) as reported previously, and bulls had significantly higher pre-slaughter behaviour scores, but there were no castration effects on levels of plasma metabolites or on-farm temperament scores. Relationships between behavioural traits and measures of growth rate and meat quality based on treatment-adjusted residuals were low and non-significant. It is concluded that despite on-farm temperament scores being moderately repeatable, these measures were not associated with differences in pre-slaughter behaviour, and neither of these traits was associated with growth rate or measures of meat quality. KEYWORDS: animal behaviour; meat quality; meat pH; cortisol; growth rate; tenderness. }, issn = {1176-5283}, author = {Burnham DL and Purchas RW and Morris ST} } @conference {41397, title = {Conjugated linoleic and trans-vaccenic acids in grass-fed beef and lamb}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {63}, year = {2003}, month = {Jan}, pages = {21-24}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Queenstown}, abstract = {Cis-9 trans-11 conjugated linoleic acid (CLA) found in ruminant milk and meat has several human health benefits of which the anti-cancer effect is the most prominent. Trans-vaccenic acid (TVA) is a precursor of CLA and can be considered as another dietary source of CLA. This paper uses data from three published papers to compare the CLA and TVA concentrations in the longissimus lumborum muscle (LL) from cattle and lambs, to determine the within- group variation, and to identify factors influencing this variation. The paper discusses the contribution lean beef and lamb can make to the estimated human daily required intake (DRI) for CLA. The CLA and TVA content was measured in the LL from two groups of cattle (n = 15 and n = 100) and two groups of lambs (n = 30 and n = 12). CLA and TVA concentrations in the total fatty acids (TFA) was higher (P<0.001) in lamb than in beef. The coefficients of variation within each group of animals ranged from 23-41\% for CLA and 25-68\% for TVA, indicating a large variation in the concentration of these fatty acids among animals. A number of factors contributed to these differences but the largest difference was found in lambs, where there was a 41\% higher (P<0.01) CLA concentration in the TFA from lambs born to ewes with high CLA concentrations than from lambs born to ewes with low CLA concentrations in their milk fat. A 100g portion of lamb containing 2-4\% lipid could contribute 2-5\% of the estimated 750mg DRI of CLA for humans. However, if dietary TVA was assumed to be equivalent to CLA, then lamb could contribute 13-15\% of the DRI. We conclude that lamb can provide a significant proportion of the DRI for CLA for humans and there is scope for farmers to further increasing the CLA and TVA content of beef and lamb.}, issn = {1176-5283}, author = {Knight TW and Morris CA and Purchas RW and Agnew M} } @conference {41345, title = {Ranking Romney sires on carcass value from a progeny test}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {62}, year = {2002}, month = {Jan}, pages = {183-187}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {Interest in the meat-producing potential of rams of dual-purpose breeds such as the Romney has increased in recent years. To cater for this a group of Manawatu ram breeders have established a progeny test to determine sire differences in carcass value (CV) estimated as the sum of the value of individual carcass parts. In 2000-2001, detailed information was collected on 139 carcasses representing 12 sires. The average carcass weight and CV ({\textpm} sd) were 14.9 {\textpm} 1.9kg and $81.76 {\textpm} $10.76 respectively. A stepwise regression model with residual CV as the dependent variable was used to determine whether sire rankings on CV could be satisfactorily achieved by weighing only selected carcass parts. Weight of boneless leg (BL) explained the most variation with an r2 of 0.84. The addition of the weights of the frenched rack (FR) striploin (ST) each significantly (P<0.001) increased the amount of variation explained (r2 = 0.90), and increased the rank correlation between estimated and actual sire-group rankings from 0.71 to 0.95. A minimal model to rank the sires in this Romney progeny test is CV= -72.06+30.42*FR + 24.39*ST + 12.36*BL. Use of this model would avoid incurring the costs of weighing all carcass parts. }, issn = {1176-5283}, author = {PL Johnson and Purchas RW and Blair HT} } @conference {41186, title = {Differences in wool characteristics in lines of sheep with high or low levels of backfat thickness}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {159-161}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Relationships between backfat thickness and wool characteristics for lines of Coopworth and Southdown sheep, selected for or against backfat thickness, were studied between years and between different age classes. On average, the lean Coopworth line grew 230 g more greasy wool (P < 0.001), which was 1.7 {\textmu}m finer (P < 0.001) and less variable in diameter (P < 0.05) than the fat line. Other measured wool characteristics were not affected. The Southdown lines did not differ in fibre diameter, variability of diameter or curvature, within age groups. Southdown lambswool was finer (P< 0.001) than hogget or ewe wool (23.6 {\textpm} 4.9, 27.0 {\textpm} 5.6 and 26.7 {\textpm} 5.4). Fibre diameter differences observed in the Coopworth lines may have been a founder effect, as subsequent selection had little impact on it. Selection for leanness increased greasy fleece weight without affecting fibre diameter or staple length. }, issn = {1176-5283}, author = {Merrick NC and Baird DB and McEwan JC and Purchas RW} } @conference {41181, title = {A program to assess the efficiencies of sheep-meat production systems: A teaching aid}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {135-138}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {A computer program written in Visual Basic within a spreadsheet was developed to illustrate how the efficiency of a sheep-meat production system varies when changes are made in any or all of 32 variables. System performance is expressed in monetary terms as either the efficiency (E) in dollars returns per dollar cost (with a break-even value of 1) or as a profit. Costs and returns for ewes, rams and lambs are taken into account, and all are expressed on a per ewe per year basis. A single per kilogram price for mutton is used, but for lambs, the proportion falling into various classes at any carcass weight is calculated using a specified GR/carcass weight relationship in a separate simulation program. Relationships within the E-program are based on published data, such as those in lamb feed requirement tables. This program has proved useful as an aid to evaluating some repercussions of making various combinations of changes to sheep-meat production systems. }, issn = {1176-5283}, author = {Purchas RW} } @conference {41012, title = {Calpain and calpastatin activity in muscle from genetic lines of lambs selected for divergent levels of fatness.}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {58}, year = {1998}, month = {Jan}, pages = {143-145}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {There is widespread interest in the extent to which genetic factors influence meat quality. In this study we examined meat quality characteristics and the activity of the calpain protease system in M. longissimus lumborum (LL) from backfat selection lines of Southdown lambs. The high fat line produced heavier carcasses with greater soft tissue depth GR. LL from the high fat line animals had a lower ultimate pH and was significantly more tender at 24h post-mortem using the MIRINZ tenderometer but not the Warner-Bratzler peak force. There was a decline in m-calpain and calpastatin activity but not m-calpain in the 9h post-mortem. There were no significant differences in the levels of the calpains or their inhibitor between high and low backfat lines. However, when the results were adjusted for pH, the 20 min calpastatin levels were highest for the sire group that had the highest peak force value. }, issn = {1176-5283}, author = {Morton JD and Bickerstaffe R and Purchas RW} } @conference {40990, title = {Growth curves and productivity of Holstein-Friesian cows bred for heavy or light mature live weight}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {58}, year = {1998}, month = {Jan}, pages = {68-72}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {This paper presents data for live weights (LW) from birth to maturity, and for yields of milk and milksolids (MSY) per lactation, from two lines of Holstein-Friesian cows bred for heavy (H) or light (L) mature LW. Compared with the Brody, Gompertz and Logistic functions, the Von Bertalanffy function provided the best fit to the LW data, and prediction from this function has been used in the following analyses. The breeding values (BV) for LW of the sires (H: 86.3 kg; L: 31.0 kg) and maternal grandsires (MGS) (H: 55 kg; L: 38 kg) used to develop the H and L LW lines were higher (P<0.001) for the H line than for the L line, and they were significantly associated with the actual birth weight (H: 41 kg; L: 35 kg) and mature live weight (H: 520 kg; L: 467 kg) of the cows. The heavy sires also had significantly higher BV for yield of milk (H: 1037 l; L: 737 l), milkfat (H: 33.0 kg; L: 27.5 kg), and milk protein (H: 31 kg; L: 22 kg), and the H cows produced more milk (H: 4708 l; L: 4323 l), and MSY (H: 364 kg; L: 348 kg) than the L cows. However, L sires had slightly higher (P = 0.07) value for Breeding Worth than the H sires (H:37; L:46), and there were only small differences in yields of milk or MSY between the two lines when these were expressed per kg of LW, per kg of LW0.75 or per tonne of dry matter required (H: 84 kg MSY/tonne DM; L: 87 kg MSY/tonne DM). The results indicate that the extra MSY by the H cows (+ 16 kg) almost compensated for the effect of their extra LW (+ 46 kg), so that the H cows were only slightly less efficient than the L cows, as predicted by their respective sire{\textquoteright}s Breeding Worth. }, issn = {1176-5283}, author = {Garcia-Muniz JG and Holmes CW and Garrick DJ and Lopez-Villalobos N and Wickham BW and Wilson G and Brookes IM and Purchas RW} } @conference {40958, title = {Short-Term Grain Feeding and its Effect on Carcass and Meat Quality.}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {57}, year = {1997}, month = {Jan}, pages = {275-277}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Forty-five crossbred steers weighing 540-580 kg were assigned to three treatment groups. Group 1 received pasture only for 58 days; Group 2 grazed at a similar herbage mass to Group 1 and were supplemented with 4 kg/hd/day of a concentrate ration; Group 3 were on a feedlot and fed 8 kg/hd/day of concentrate together with 2.0 kg/hd/day of straw. Groups 2 and 3 each had a 28 day pre-conditioning period followed by a 30 day concentrate feeding period. Final fasted liveweight, liveweight gains, and carcass weights for concentrate, concentrate plus pasture and pasture alone groups were 546 {\textpm} 9, 548 {\textpm} 9, 547 {\textpm} 8 kg; 0.33 {\textpm} 0.09, 0.42 {\textpm} 0.09, -0.05 {\textpm} 0.09 kg/hd/day and 293 {\textpm} 7, 315 {\textpm} 4 and 313 {\textpm} 4 kg, respectively. The concentrate plus pasture and pasture only fed groups had greater fat depths. Ultimate pH was slightly lower in concentrate fed than pasture fed cattle but there were no differences in fat colour or tenderness as measured in the laboratory. Plasma carotene levels were significantly lowered by a factor of 10 in the concentrate fed group compared to the grass fed group, but this did not affect fat colour when measured subjectively at the meat processing plant or objectively in the laboratory. Apparently feeding concentrates for 30 days is insufficient to affect fat colour characteristics. }, issn = {1176-5283}, author = {Morris ST and Purchas RW and Burnham DL} } @conference {40957, title = {Sources of variation in the ultimate pH of M. longissimus from prime steers.}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {57}, year = {1997}, month = {Jan}, pages = {271-274}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The ultimate pH (pHult) of beef is an important quality determinant, that can be affected by pre-slaughter muscle glycogen concentrations. The two trials reported here evaluated relationships between pre-slaughter conditions and behaviour of mobs ofsteers processed at Manawatu Beef Packers Limited and the subsequent incidence of high-pH beef. Trial 1 involved 405 2- and 3-year steers in 12 mobs, with a mean ({\textpm}sd) carcass weight of 341.2 ({\textpm}28.2)kg. Cattle were held for either c. 3h prior to slaughter (1/2of each mob) or c. 27h. Mean carcass weight was lower for the 27h-mobs (P < 0.01), but the extra 24h holding time had no effect on mean pHult , bruising score, carcass fat depth, or meat colour. The percentage of carcasses with a pHult> 6.0 varied from 0 to 27\%, but was not closely related to any of the pre-slaughter conditions monitored (eg. feeding levels, conditions during yarding, loading and transport,weather conditions, and conditions at the plant).}, issn = {1176-5283}, author = {Purchas RW and Keohane BE} } @conference {40842, title = {A comparison of unbred and once-bred lamb production}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {56}, year = {1996}, month = {Jan}, pages = {307-309}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The once-bred lamb (OBL) production system involves mating ewe lambs at 8 months of age to be slaughtered at approximately 15 months of age after rearing a lamb. This study compared the performance of bred ewe lambs (}, issn = {1176-5283}, author = {Johnston JB and Morris ST and Purchas RW and McCutcheon SN and Parker WJ} } @conference {40802, title = {Future directions for meat research and development in New Zealand}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {56}, year = {1996}, month = {Jan}, pages = {147-150}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {If meat research, from production through to the marketplace, is not adequately funded, then much of the research needed to improve New Zealand}, issn = {1176-5283}, author = {Kirton AH and Purchas RW} } @conference {40869, title = {Plasma carotenoid concentrations early in life can be used as a selection criterion for fat colour in heifers}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {56}, year = {1996}, month = {Jan}, pages = {398-399}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Plasma carotenoid (PC) concentrations were measured at 2-5 month intervals in 20 Hereford x Jersey (HJ) and 20 Hereford x Friesian (HF) once bred heifers from 10-35 months-of-age. Half of the heifers were slaughtered at 31 months-of-age and the rest at 35 months-of-age. The colour of the subcutaneous and intermuscular fat was measured using a chromameter and c* values were calculated. Subcutaneous and intermuscular fats in HJ heifers were yellower (i.e. they had higher c* values) than in HF heifers. Regression equations that included breed, date of slaughter and PC concentrations at 10-12 months-of-age, accounted for 56\% of the variation in c* values for subcutaneous fat and 40\% of the variation in c* values for intermuscular fat (P<0.001). }, issn = {1176-5283}, author = {Death AF and Knight TW and Purchas RW and Morris ST and Burnham DL} } @conference {40809, title = {Repeatabilities of blood plasma metabolites and their associations with leanness in genotypes showing a wide divergence in carcass composition}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {56}, year = {1996}, month = {Jan}, pages = {180-183}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Strain differences in lean : fat partitioning were typified by a marked contrast in a lean growth index giving equal but opposite emphasis to the weights of protein and fat, in line with previous publications. Strains showed characteristic differences in blood metabolites which did not necessarily reflect genetic variations within a strain and correlated responses to within-breed selection for changes in body composition. High repeatabilities of blood metabolites within a strain were found for pasture-fed lambs aged between 5 and 14 months for samples collected on the same day following overnight fasts of 20 vs 24 hours, but were lower for samples taken from fasted animals at different ages. Between-age within- strain repeatabilities (averaged across two trials) were moderate for plasma urea (0.24) creatinine (0.38) and non-esterified fatty acids (0.18), but low for beta-hydroxybutyrate (0.09). Similar moderate heritability estimates were found for urea and creatinine. Although standard errors were very high for this small dataset based on only 12 sires, estimates for carcass composition were in broad agreement with other more reliable published values. Also in line with other results, sire-progeny variations in urea and beta- hydroxybutyrate were more positively related to carcass protein than carcass fat, while the reverse was true for creatinine. Metabolically contrasting pairs of metabolites showed potentially useful predictive associations with sire- progeny variations in protein:fat partitioning.}, issn = {1176-5283}, author = {Clarke JN and Binnie DB and Dobbie JL and Jones KR and Mowat CM and Purchas RW and Uljee AE} } @conference {40682, title = {Effects of genotype and nutrition on sheep carcass fat and eye muscle development between weaning and 14 months of age}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {55}, year = {1995}, month = {Jan}, pages = {104-107}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Although several studies have implicated cortisol in the control of body composition in sheep, the precise mechanisms are unclear. Cortisol basal concentration and response to an ACTH challenge was studied in Coopworth wethers selected for (Fat) or against (Lean) fatness in both the fed and 48 hour fasted states at two stages (15 and 33 weeks). The aim was to investigate whether fasting, age or genotype would influence cortisol secretory parameters. Mean basal cortisol concentration was higher for fasted than fed lambs (13.6 versus 8.9 ng/ml, p<0.001), but did not differ significantly with genotype or overall stage of development. Maximal cortisol response to ACTH was greater for the fat than the lean genotype, at both 15 weeks (86.3 versus 65.3 ng/ml, p<0.01) and 33 weeks (108.2 versus 91.1 ng/ml, p<0.01) of age. Maximal cortisol response was also significantly greater with fasting and increasing age, but the effect of fasting on cortisol increase was greater at 15 than 33 weeks of age. Clearance of cortisol was significantly slower after fasting, but unaffected (p>0.05) by genotype and development. Basal cortisol concentrations was not associated with differences in body composition between the fat and lean genotypes. However the larger maximal response in the fat genotype may indicate that the adrenal gland plays a role in determining body composition. }, issn = {1176-5283}, author = {Binnie DB and Clarke JN and Clayton JB and Mowat CM and Purchas RW} } @conference {40601, title = {A comparison of the carcass and meat quality of Awassi-cross and Texel-cross ram lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {54}, year = {1994}, month = {Jan}, pages = {209-214}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The Awassi is a fat-tailed sheep breed from the Middle East that has recently been imported into New Zealand for live-sheep export and for milk production. The aim of the current trial was to compare the carcass and meat quality of Awassi-cross and Texel-cross ram lambs. There were 36 lambs in each sire-breed group with an equal number from Romney and Poll Dorset ewes. Lambs were allocated at random within breed-cross groups to groups of 9 that were slaughtered in either May or August to give an overall mean carcass weight of 19.7kg. The Awassi-sired group had a lower dressing-out percent (44.4 vs 44.8; P<0.01), similar GR tissue depths (7.6 vs 8.4 mm) but more weight-adjusted leg fat (537 vs 446g. P<0.001). The most clear-cut difference was in carcass shape with Awassi-cross lambs having longer carcasses (1068 vs 1013 mm), longer legs, and longer, heavier leg bones at a constant carcass weight (all P<0.001). The shape difference at a common carcass weight was also reflected in the Awassi-cross lambs having lower leg muscle to bone ratios (3.49 vs 3.88), muscle weight (2047 vs 2172 g), and muscularity values (0.436 vs 0.488) than the Texel-cross lambs, and shallower longissimus muscle depths (28.0 vs 29.8 mm)(all P<0.01). Differences between Awassi and Texel-sired lambs in tenderness (shear values) and colour (L*,a*,B* values) of the semimembranosus muscle were not significant. Differences between dam-breed groups were generally small, although, relative to the Poll Dorset, the Romney-cross group had lower weight-adjusted longissimus depths (28.2 vs 29.6 mm) and leg muscle to bone ratios (3.57 vs 3.80(both P<0.01). When adjusted to the same carcass weight, lambs slaughtered in August had lower dressing-out percentages (42.6 vs 46.6), lower GR depths (6.7 vs 9.3 mm, longer carcasses (1063 vs 1018 mm), and poorer leg muscularity (0.450 vs 0.474) than those slaughtered in May (all P<0.02). In this study Awassi-cross carcasses were inferior to those of Texel-cross lambs in terms of composition and shape, but differences in meat quality not apparent. }, issn = {1176-5283}, author = {Holloway IJ and Purchas RW and Power MT and Thomson NA} } @conference {40561, title = {A prolonged change in body composition induced by endocrine manipulation of the neonate}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {54}, year = {1994}, month = {Jan}, pages = {51-54}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The ability of endocrine manipulation of the neonate to effect prolonged changes in body composition was examined. Treatment of lambs with recombinant bovine somatotropin (rbST) at doses of 0.1 or 0.3 mg/kg liveweight/day for 11 weeks from birth elevated circulating ST concentrations (P<0.01) but had no effect on circulating concentrations of insulin-like growth factor-1 or on liveweight gain compared with excipient-treated lambs. However, at 8 months of age (5 months after cessation of treatment), ultrasound backfat depths (Mean{\textpm}SE) were significantly (P<0.05) higher in lambs previously treated with excipient (3.4{\textpm}0.3 mm) than in those treated with rbST at 0.1 mg/kg (2.8{\textpm}0.3 mm) or 0.3 mg/kg (2.5{\textpm}0.3 mm). In a second study, rats were treated with saline vs. 0.2 ug/g rbST vs. 0.4 ug/g rbST vs. 0.2 ug/g pituitary ovine prolactin (poPRL) vs. 0.4 mu/g poPRL for the first 21 days of life. At 120 days of age they were euthanased, selected fat depots weighed and the carcasses analysed for fat content. Neonatal treatment with rbST or poPRL significantly (P<0.05) reduced weight of the subcutaneous scapular fat depot (1.08{\textpm}0.18 vs. 0.46{\textpm}0.17 vs. 0.52{\textpm}0.18 vs. 0.50{\textpm}0.17 vs. 0.49{\textpm}0.17 g) and carcass fat content (5.88{\textpm}0.27 vs. 5.03{\textpm}0.26 vs. 4.58{\textpm}0.27 vs. 5.28{\textpm}0.26 vs. 4.70{\textpm}0.26\%) but did not influence weights of the subcutaneous abdominal, genital or perirenal fat depots. These results suggest that endocrine manipulation of the neonate may offer a means of producing desirable changes in the composition of production animals while avoiding consumer resistance to the use of hormonal growth promotants close to the time of slaughter. }, issn = {1176-5283}, author = {McCutcheon SN and Kadim IT and Wickham GA and Purchas RW} } @conference {40537, title = {A comparison of carcass and meat characteristics and organ weights of castrate and entire male buffalo and cattle}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {53}, year = {1993}, month = {Jan}, pages = {407-412}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Research has shown that sheep from a Massey University flock selected for increased fleece weight (FW) for thirty-six years have higher faecal egg counts (FEC) than unselected controls (C). The purpose of this trial was to determine whether differences in FEC between FW and C sheep accurately reflected differences in adult worm burdens. In addition levels of mucosal mast cells, and their relationship with worm burden in each line were examined. Thirteen one year-old rams from each flock were housed indoors and artificially infected with larvae of three species of nematode parasite: Haemonchus contortus, Ostertagia circumcincta, and Trichostrongylus colubriformis. FECs were monitored and adult worm burdens, and levels of mucosal mast cells, determined following slaughter 28 days after infection. FECs were higher in FW than C sheep (4204 vs 300 epg, p<0.0001), as were numbers of adult Haemonchus (1151 vs 249, p<0.01) and Ostertagi (2268 vs 600, p<0.05). Numbers of Trichostrongylus (5838 vs 5266) and total worm burden (9257 vs 6115) were not significantly different between lines. A {\textquoteright}Total Pathogenic Index{\textquoteright}, calculated from the number of parasites of each species present in the total burden, was higher in FW than C sheep (3.8 vs 1.5, p<0.005). The regression coefficient relating FEC to worm burden was larger in FW than C sheep (0.35 vs 0.05 eggs per g faeces/worm, p<0.01). Levels of mucosal mast cells did not differ significantly between lines, but were inversely related to number of worms in FW sheep. There was no such relationship in C sheep. It is concluded that while the large differences in FEC between lines overestimates the difference in total worm burden, FW sheep do carry significantly more worms of the abomasal species H. contortus and O. circumcincta than C sheep. FW sheep are able to maintain superior wool production in spite of this potentially more pathogenic worm burden. The mucosal mast cell response to parasitic infection also appears to have been changed by selection. }, issn = {1176-5283}, author = {Purchas RW and Thomson NA and Waghorn GC and Death AF} } @conference {40521, title = {Hormone/metabolite levels in young rams as predictors of genetic merit for backfat depth and fleeceweight}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {53}, year = {1993}, month = {Jan}, pages = {335-338}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Three newly developed electronic lamb carcass grading probes (Hennessy Grading Probe, AUS-Meat Sheep Probe, Swedish FTC Lamb Probe) and one developmental probe (Ruakura GR lamb probe) were tested for accuracy in classifying 6 groups, each of approximately 50 lamb carcasses. They were assessed for accuracy and suitability for use on- line on the lamb dressing chain for objectively classifying lamb carcasses. Probe measurements were compared with manual GR (sometimes used at present) and Toland (can measure total tissue depth between the ribs) probe measurements for accuracy of predicting both GR on the right side of each carcass, and also carcass water (indicating muscle) and fat content. All probes combined with carcass weight accounted for over 70\% of the variation (R2) of GR right with the GR left prediction accounting for 92\% of the variation in GR right. The 3 commercial electronic probes used at chain speed combined with carcass weight could account for 36- 49\% of the variation in \% water and fat with the manual GR probe (right) doing only slightly better on the chilled carcass. Chilled carcass measurements are expected to give better results. The electronic probe results are consistent with overseas results where probes are in use for objectively grading the carcasses of meat animals.}, issn = {1176-5283}, author = {Kuhn B and Blair HT and Purchas RW and McCutcheon SN} } @conference {40535, title = {Relationships between objective and subjective measurements of carcass muscularity}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {53}, year = {1993}, month = {Jan}, pages = {397-402}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {No abstract supplied }, issn = {1176-5283}, author = {Abdullah AY and Purchas RW and Davies AS and Kirton AH} } @conference {40382, title = {Growth and venison production from red deer grazing either red clover or perennial ryegrass/white clover pasture}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {52}, year = {1992}, month = {Jan}, pages = {81-84}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Computers will become an increasingly important tool in animal management, as well as in most other areas of agricultural endeavour. Computers are commonly used for recording and analysing both research and centrally located production data, but seldom for on-farm use. This discussion concentrates on the traits that can be recorded at the farm level, and how these records can be used. System specifications for successful on-farm use are also outlined. }, issn = {1176-5283}, author = {Semiadi G and Barry TN and Wilson PR and Hodgson J and Purchas RW} } @conference {40370, title = {The value of ultrasound in assessing the leg muscling of lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {52}, year = {1992}, month = {Jan}, pages = {33-36}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Faecal worm egg counts (FEC) were recorded on 779 lamb progeny in a performance recorded flock in Northland during summer-autumn 1990 to determine breed and sire variations. Progeny were ram lambs born in 1989 representing 4 Perendale, 4 Romney and 7 cross-bred sires. The study protocol was that the lambs remained undrenched until the mean FEC of representative {\textquoteright}monitors{\textquoteright} reached 1000-1500 eggs/g. Then all stock were faecal sampled, drenched and the protocol repeated. Full samplings occurred on 12 February (FEC1) and 12 March (FEC2). All animals grazed as one mob throughout the programme. There were significant variations within and between breeds in FEC. Perendale and Crossbred lambs had significantly lower faecal egg outputs than Romneys on both occasions (FEC1=3560, 4073, 4757; FEC2=2535, 3242, 3737, respectively). One possible explanation of the results is that Perendales selectively avoid parasite contamination on pasture through differences in grazing behaviour. Alternatively, they may have consumed less pasture and larvae because they were lighter. If these are not the cases these data suggest that Perendales in this flock may be more resistant to internal parasites. }, issn = {1176-5283}, author = {Ward BG and Purchas RW and Abdullah AY} } @conference {40283, title = {Effects of immunisation against LHRH on body growth, scrotal circumference, and carcass composition in yearling Red deer stags}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {51}, year = {1991}, month = {Jan}, pages = {63-66}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Mammary tissues from virgin, prepartum and lactating ewes were examined by in situ hybridisation with a 35S labelled cRNA probe derived from the bovine alpha-lactalbumin gene. Expression of alpha- lactalbumin was absent in the virgin udders. In the pregnant gland, alpha-lactabumin expression was found in some secretory alveoli but not in others, even though they appeared histologically similar, containing milk or colostrum and fat globules. Fully lactating ewes have several levels of alpha-lactalbumin expression. In secretory epithelium, it was high in collapsed thick walled lactating alveoli, slightly less in distended thin walled lactating alveoli with homogeneous contents and absent from alveoli containing an abundance of large fat globules. Beta-cytophasmic actin expression was the reverse of this. These observations are intriguing and suggest a number of hypotheses. Firstly; that alpha-lactalbumin gene expression is linked to the long term secretory activity of cells and drops off once cells are resting or regressing. Secondly; that alpha-lactalbumin gene expression is highest in those alveoli which are "filling up" and lowest in those which are full or have just been milked out. That is, there are cyclical variation in expression. And thirdly; that there is distinct compartmentalisation in the lactating gland, and synthesis of alpha- lactalbumin mRNA (and the protein?) occurs in cells which synthesise little fat. }, issn = {1176-5283}, author = {Freudenberger DO and Wilson PR and Purchas RW and Barry TN and Moss BA and Trigg TE} } @conference {40204, title = {Plasma urea dilution patterns in Southdown ram lambs from high and low backfat selection lines}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {50}, year = {1990}, month = {Jan}, pages = {105-108}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Exogenous progesterone and oestradiol benzoate (OB) were used in long-term ovariectomised red deer to investigate a simple technique for induction of oestrus. Up to 12 days of intravaginal progesterone (CIDR-S; replaced at 4 day intervals) was followed 24h later by a single intramuscular injection of OB. Continual observations (for behavioural oestrus) and blood sampling every 6h (for plasma LH concentrations) were conducted over the subsequent 48h period. In Experiment 1 (December), 12 days of progesterone preceded 0, 1.0, 2.5 or 5.0 mg OB. Onset of oestrus (28-44h post-OB; mean 33h) was similar in all treated hinds. Plasma LH concentrations fell (P<0.01) after OB administration, followed 30 to 36h later by a dramatic increase (to 6.4 ng/ml) indicative of pre-ovulatory-like LH surge. Hinds receiving no OB exhibited 4\% of all mounting interactions but showed no increases in LH concentration. Experiment 2 (January) consisted of no treatments or 12 days or progesterone followed by 0, 0.1 or 1 mg OB resulted in suppression of plasma LH after OB. However, all other plasma LH and behaviour responses elicited were anomalous. In Experiment 3 (February), 0,4, 8, or 12 days of progesterone pretreatment were terminated 24 hours prior to administration of 1 mg OB. Plasma progesterone concentrations were elevated above 1 ng/ml during all progesterone treatments. Onset of oestrus was observed later (P<0.5) after 4 days of progesterone treatment (33.4h; sem 1.2h). Tonic plasma LH secretion was elevated (P<0.01) from Experiment 1 through to Experiment 3 but the plasma LH suppression in response to OB was similar in all 3 experiments. These results indicate that oestrus can be induced in the red deer hind by at least four days of intravaginal progesterone treatment followed by i.m. oestradiol benzoate administration 24h after progesterone removal. }, issn = {1176-5283}, author = {Abdullah AY and Purchas RW and McCutcheon SN and Van Dinther PC} } @conference {40228, title = {Responses in venison production to grazing pastures based upon perennial ryegrass or annual ryegrass and to immunisation against melatonin}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {50}, year = {1990}, month = {Jan}, pages = {279-286}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Annual patterns of fur growth are described from captive possums skin biopsied at three-weekly intervals between April 1985 and May 1987. Counts of hair follicles showed that follicle activity was poorly synchronised between individual possums, with maxima occurring mostly in spring and summer. No more than 40\% of follicles sampled were active at one time in any individual. Derived follicles continued to develop in adult animals, increasing the follicle population by 23 }, issn = {1176-5283}, author = {Ataja AM and Wilson PR and Hodgson J and Hoskinson RW and Purchas RW and Varela-Alvarez H and Barry TN} } @conference {40156, title = {Liver catalase in Southdown sheep selected for high and low backfat depth}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {49}, year = {1989}, month = {Jan}, pages = {143-146}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Four pairs of shorn Cashmere-type goats, fed at 1.5 x maintenance, were exposed to air temperatures between 5}, issn = {1176-5283}, author = {Peterson SW and Purchas RW} } @conference {40135, title = {A study of early venison production from grazing red deer}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {49}, year = {1989}, month = {Jan}, pages = {25-28}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Gene maps of livestock will play an important role in the development of new animal breeding technologies based on molecular techniques. The current status of the bovine gene map is reviewed and various methods of mapping genes are discussed. The task of constructing the bovine gene map will be aided by the conservation of chromosomal segments amongst mammalian species. In particular, the detailed maps of man and the mouse can be used to rapidly establish a provisional, but extensive bovine gene map.}, issn = {1176-5283}, author = {Ataja AM and Wilson PR and Purchas RW and Hodgson J and Barry TN and Hay RJM} } @conference {40083, title = {The stability of the relationship between subcutaneous fat percent in the rack and the side for Southdown ram carcasses}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {48}, year = {1988}, month = {Jan}, pages = {29-32}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The carcass composition of pasture-fed crossbred ram lambs of the Finn, Texel, Oxford Down, Border Leicester and Suffolk breeds was compared at the Hopuhopu Animal Quarantine and Research Station in 1987. Early results were in close agreement with overseas studies which have highlighted the low subcutaneous fat depth of Texel crossbreds in comparison with lambs from Suffolk sires at the same carcass weight. Finn crossbreds were relatively lean subcutaneously but had relatively more kidney fat. Texel crosses showed superior eye muscle development at constant carcass weight.}, issn = {1176-5283}, author = {Kadim IT and Purchas RW and Rae AL and Barton RA} } @conference {39992, title = {Consideration of alternative lamb drafting strategies}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {46}, year = {1986}, month = {Jan}, pages = {49-54}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The saleable meat, bone and trimmed fat content was measured on the sides of 643 steer, 273 heifer and 1086 bull carcasses. Saleable meat yield declined from approximately 70\% in grade M to 59\% in grade T for steers and heifers, while fat trim increased from approximately 8\% in grade M to 25\% in grade T. Carcass saleable meat yield in bulls was almost constant (72.6 }, issn = {1176-5283}, author = {Garrick DJ and Purchas RW and Morris ST} } @conference {39947, title = {The application of a lean growth index in ram breeding flocks}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {45}, year = {1985}, month = {Jan}, pages = {77-80}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Carcass composition is determined by the relative partitioning of metabolisable energy intake among protein, fat and heat. Protein deposition is the net difference between rates of protein synthesis and protein degradation in tissues; synthesis and degradation proceeding at rates several times that of deposition. Relatively small changes in rates of protein synthesis or degradation may result in relatively large changes in deposition. The energy cost of protein synthesis may reduce energy available for fat deposition. The manipulation of carcass fat content may be more readily achieved by increasing lean growth than reducing fat deposition. Development of accurate methods for measuring protein synthesis should facilitate understanding of the mechanisms by which lean animals are grown and the selection of growth promotants useful in the production of leaner carcasses.}, issn = {1176-5283}, author = {Dodd CJ and Bennett GL and Purchas RW} } @conference {39946, title = {The calculation of a simple lean-growth index for young sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {45}, year = {1985}, month = {Jan}, pages = {73-76}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Display life of frozen lamb chops was unaffected by breed or sex. Chops shrink-wrapped in oxygen permeable film had a longer display life than those vacuum packaged in a film of low oxygen permeability. Chops cut from frozen loins, then packaged had a significantly longer display life than chops cut from chilled loins, packaged, and then frozen. Ram lamb chops had significantly higher pH values than those from wethers and ewes. Chops from Romney-cross lambs had lower pH values than those from Coopworth-cross and Perendale-cross lambs. Meat pH decreased slightly but significantly during storage.}, issn = {1176-5283}, author = {Purchas RW and Bennett GL and Dodd CJ} } @conference {39921, title = {Fatness of lambs grazed on {\textquoteright}Grasslands Maku{\textquoteright} lotus and {\textquoteright}Grasslands Huia{\textquoteright} white clover}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {44}, year = {1984}, month = {Jan}, pages = {219-222}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Crossbred lambs involving specialist meat breed (Expt. A) or long-woolled breeds (Expt. B) were slaughtered at ages ranging from 12 to 30 weeks. Carcasses were classified retrospectively into current export grades according to their weight and fat measurement GR. In both experiments measurement GR was related to carcass weight (r=0.57 to 0.83) and increased, on average, by just over 1 mm per kg carcass weight increase. Proportions of carcasses grading {\textquoteright}trimmer{\textquoteright} or {\textquoteright}overfat{\textquoteright} increased at carcass weights above 15 kg or at slaughter ages greater than 18 weeks. In Expt. A, 4\% of carcasses graded {\textquoteright}overfat{\textquoteright} at the 12 week slaughter age and 81\% at 30 weeks. There was little difference in the grade distribution of carcasses among sire breeds in Expt. A (Southdown, Suffolk and Dorset Down) but in Expt. B lambs reared by Corriedale ewes showed higher proportions of {\textquoteright}trimmer{\textquoteright} (25\%) and {\textquoteright}overfat{\textquoteright} (18\%) carcasses compared with those reared by Romneys (10\% and 2\% respectively). It is suggested that the higher carcass fat of lambs from Corriedale ewes is due partly to greater milk consumption compared with those suckled by Romneys.}, issn = {1176-5283}, author = {Purchas RW and Keogh RG} } @conference {39725, title = {The repeatability of ultrasonic fat-depth measurements made on sheep up to 18 months of age}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {41}, year = {1981}, month = {Jan}, pages = {133-139}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, issn = {1176-5283}, author = {Purchas RW and Rae AL and Barton RA and Beach AD} } @conference {39639, title = {A comparison of the fatness of weaned and unweaned lambs}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {39}, year = {1979}, month = {Jan}, pages = {211-216}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, issn = {1176-5283}, author = {Purchas RW} } @conference {39402, title = {The Effect of Cortisol Acetate Administration on Growth and Carcass Quality of Lambs (Summary only)}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {33}, year = {1973}, month = {Jan}, pages = {192}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, issn = {1176-5283}, author = {Purchas RW} }