@conference {89224,
	title = {A comparison of aspects of the reproductive success of ewe lambs and mixed age ewes joined over the same period},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {73},
	year = {2013},
	month = {Jan},
	pages = {76-78},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {<p>Ewe lamb breeding at 7 to 8 months of age in extensive production systems, such as utilised in New Zealand, has a number of advantages including higher net profit from lamb production, improved utilisation of spring herbage, improved ewe lifetime performance and improved reproductive rate throughout the flock (Kenyon et al. 2012). However, in comparison to mature ewes there are limitations to ewe lamb breeding which include a lower lambing percentage, lower lamb birth weight\&nbsp; and lower lamb survival (Annett \&amp; Carson 2006; Kenyon 2012).</p>
},
	issn = {1176-5283},
	author = {Corner RA and Blair HT and Morris ST and Kenyon PR}
}
@conference {41940,
	title = {The effect of maternal nutrition during gestation on the reproductive success of female progeny as 2-tooths},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {434-438},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {The inter-generational effect of birth rank and nutrition during pregnancy was assessed by examining the reproductive success of female progeny at their first mating at 2 years of age. Fifty-six ewes born as a twin or triplet and whose dam was maintained on 2 or 6 cm sward height from mid-pregnancy to parturition were synchronised and bred to Romney rams. Pregnancy diagnosis was conducted using ultrasound on day 71 from the start of mating (P71). All ewes were maintained as one mob under commercial farming conditions throughout pregnancy. Within 12 hours of birth lambs were ear tagged, weighed and body dimensions (CRL, girth, forelimb and hind limb lengths) were recorded. Lamb live weights were also recorded at day 48 after the mid-point of lambing (L48). Fifty-one ewes lambed of the 56 ewes that were bred. Twin-born ewes had significantly longer gestation lengths (by 1.3 days) than triplet-born ewes. Singleton lambs born to triplet-born ewes were significantly (P<0.05) lighter (4.6 kg) at birth than singleton lambs born to twin-born ewes (5.1 kg). Singleton lambs whose grand-dams were maintained on 2cm pastures during pregnancy and whose dam was born as a twin had significantly (P<0.05) longer hind limbs than their counterparts whose grand dam was maintained on 6 cm and whose dam was born a triplet but they did not differ in birth weight. Dam birth rank and the nutritional treatment of their grand-dam had no significant effect on twin-lamb live weight and body dimensions at birth. These results suggest that selecting triplet ewe lambs for breeding could have detrimental effects on flock productivity. In addition a previous study involving the same animals reported triplet born ewes displayed poorer maternal behaviour. To the authors knowledge this is the first finding of this kind and could have implications for ewe selection on New Zealand farms. },
	issn = {1176-5283},
	author = {Corner RA and Kenyon PR and Stafford KJ and West DM and Morris ST}
}
@conference {41689,
	title = {The effect of nutrition during pregnancy on the behaviour of adolescent ewes and their lamb(s) within 12 hrs of birth},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {439-443},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Hogget mating has become more common in recent times as a management strategy to produce additional lambs. The productivity of hogget mating is limited by low lamb birth weights and poor lamb survival. A study has shown that maternal nutrition during pregnancy in hoggets had no effect on the birth weight or survival of lambs. This study investigated the effect of nutrition during pregnancy on the post-parturient behaviour of hogget ewes and their lambs. On day 13 after the mid-point of breeding hogget ewes were stratified by breed and live weight and randomly allocated to one of three feeding regimes: Low (gained 10kg of live weight by parturition), Medium (20kg) and High (30kg). Within 12 hours of birth lambs were ear tagged and the maternal behaviour of hogget ewes was recorded using a maternal behaviour score (MBS) a five point measure of a ewe{\textquoteright}s response to the handling of her lambs. Behavioural observations of the hogget and her lamb(s) were made for 5 minutes after the completion of tagging the lamb. Singleton-bearing hogget ewes fed on the high plane of nutrition had significantly (P<0.05) greater maternal behaviour scores than singleton-bearing hoggets fed on low or medium planes. In the low fed group, significantly (P<0.05) fewer hoggets bleated in response to their lamb (60\%) compared with medium (73\%) and high (85\%) fed hoggets. Of the lambs that bleated, those born to hoggets in the medium fed group bleated significantly (P<0.05) more than lambs born to hoggets in the low or high fed groups. Feeding hogget ewes on a high level of nutrition had a positive impact on hogget and lamb behaviour within 12 hours of birth. A high level of nutrition during pregnancy may result in behaviours that increase survival of lambs born to hogget ewes. },
	issn = {1176-5283},
	author = {Corner RA and Kenyon PR and Stafford KJ and West DM and Morris ST}
}
@conference {41560,
	title = {Does ewe nutrition during pregnancy affect the metabolism of twin-born lambs?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {163-167},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {An insulin tolerance test was conducted on twin-born ewes born to dams offered sward heights of either 2 or 6 cm between day 64 and 132 of pregnancy in order to identify any alterations in the lamb{\textquoteright}s metabolism. Lambs were also categorised into groups according to birth weight (< 4.0 kg, light and > 4.0 kg, heavy). Changes in metabolism may have long term effects on growth and productivity. An insulin challenge (0.2 U/kg) was administered to ewe lambs at 8 months of age and their plasma insulin, glucose and cortisol responses were monitored. The plasma cortisol concentration of ewe lambs born to ewes offered 2cm sward height was significantly (P < 0.05) higher than ewe lambs born to ewes offered 6 cm sward height 50 minutes after the insulin challenge. No difference was found in the insulin or glucose response to the insulin challenge between dam sward height group (2 vs 6 cm). Birth weight had no effect on the insulin, glucose or cortisol response of the ewe lambs to the insulin challenge. These results show that both dam nutrition and lamb birth weight had little to no effect on the metabolic responses measured. These results suggest that lambs born to ewes offered a herbage sward height of only 2 cm or lambs with low birth weights may not show altered metabolism.
KEYWORDS: lamb; insulin tolerance test; twins; ewe nutrition; metabolism. },
	issn = {1176-5283},
	author = {Corner RA and Kenyon PR and Stafford KJ and West DM and Oliver MH and Morris ST and Blair HT}
}
@conference {41532,
	title = {Does the ewe nutrition during pregnancy affect the behaviour of ewe lambs at 1 and 2 years of age?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {29-32},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The effects of the dam{\textquoteright}s nutrition during pregnancy on her lambs{\textquoteright} behaviour in the days after birth has been examined but the longer term effects on lamb behaviour and mothering ability are not known. The behaviour of twin and triplet ewes born to ewes offered herbage with an average sward height of 2 or 6 cm from day 64 to 132 of pregnancy was recorded at 1 year of age in an arena test and at 2 years of age post lambing. A significantly (P < 0.05) greater proportion of the progeny born to dams offered 6 cm sward heights bleated in a high pitch during a 5 minute arena test. However there were no differences in minimum, median and maximum distance of the ewe from the observer or on the frequency of low- and high-pitched bleats. In addition there was no difference in the behaviour of twin- and triplet-born ewes in the arena test. At 2 years of age twin-born ewes had a significantly greater maternal behaviour score than their triplet-born counterparts. Ewe nutrition during pregnancy did not affect the maternal behaviour score of their ewe lambs after lambing at 2 years of age. These results suggest that feeding levels during pregnancy are less important than the birth rank in terms of the intergenerational effects on behaviour.
KEYWORDS: ewe nutrition; lamb; behaviour; twin; triplet. },
	issn = {1176-5283},
	author = {Corner RA and Kenyon PR and Stafford KJ and West DM and Morris ST and Blair HT}
}
@conference {41499,
	title = {Manipulating lamb birth weight and survival rate in singletons born to hoggets},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {64},
	year = {2004},
	month = {Jan},
	pages = {175-178},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {Lambs born to hoggets tend to be relatively lightweight at birth (Drymundsson, 1973; McMillan \& McDonald, 1983) and display low survival rates to weaning (McCall \& Hight 1981; McMillan \& McDonald, 1983). In addition the incidence of singletons in hoggets often exceeds 92\% (McCall \& Hight, 1981; McMillan \& McDonald, 1983). Therefore management procedures that improve both birth weight and survival of singleton lambs should have a significant effect on returns.
Severe under nutrition during pregnancy of mature ewes can lead to reduced ewe and lamb performance (Rattray 1986), which can negatively affect lamb survival. However to date minimal research under New Zealand{\textquoteright}s pastoral conditions has been undertaken in hoggets. In contrast to the mature ewe, it is also advantageous for the hogget to be increasing in conceptus-free live weight during pregnancy if lifetime performance is not to be negatively affected. Interestingly, under concentrate feeding regimes in the United Kingdom it has been reported that a high level of hogget nutrition in pregnancy, actually reduces both lamb birth weight and survival (Wallace et al., 1996).
Shearing mature ewes in mid- to late-pregnancy has been shown to differentially increase singleton- (Morris et al., 2000; Kenyon et al., 2002a) and twin-lamb birth weights (Morris \& McCutcheon, 1997; Morris et al., 1999; Kenyon et al., 2002b). Mid-pregnancy shearing has tended to increase twin-lamb survival rates (Morris et al., 1999; Kenyon et al., 2002b) but has been found to decrease singleton survival rates in one of four studies (Kenyon 2002). The effect of mid- to late-pregnancy shearing of hoggets has not been examined under pastoral conditions in New Zealand. Due to the low rate of twin pregnancies in hogget{\textquoteright}s the chance of achieving a positive affect from mid-pregnancy shearing on both a lamb birth weight and survival may be low.
The aims of these studies were to determine if hogget live weight change and shearing treatment during pregnancy could be used to manipulate singleton lamb birth weight and survival. },
	issn = {1176-5283},
	author = {Kenyon PR and Morris ST and West DM and Stafford KJ and Corner RA and Ottema K and Burnham DL}
}
