Effect of liveweight and teasing of ewe hoggets prior to breeding on lambing pattern and weight of singleton lambs

Abstract

The aim of the present study was to determine the effects of teasing on hogget lambing date, and to determine the effects of hogget liveweight at breeding and teasing on birthweights and growth rates of singleton lambs to weaning. Teasing resulted in a significantly (P < 0.001) earlier average lambing date without affecting either birth weight or lamb growth rates to weaning. This result suggests that the main benefit farmers can achieve from teasing hoggets prior to breeding is through an increase in the number of hoggets pregnant, rather than through an increase in lamb weaning weights due to earlier born lambs, as the affect on lamb weaning weight was only minor. Liveweight of hoggets pre-mating had a small, but significant (P < 0.001) positive effect on both birthweights and growth rates of singleton lambs to weaning. In addition, birthweight had a small significant (P < 0.001) positive effect on lamb growth rate to weaning. These results indicate that to achieve heavier weaning weights of lambs born to hoggets, or to allow for the option of weaning earlier, farmers should ensure hoggets attain adequate liveweights pre-mating. This affect would be additive to the known positive effects of hogget breeding liveweight on reproductive performance.

Effect of liveweight at the start of the breeding period and liveweight gain during the breeding period and pregnancy on reproductive performance of hoggets and the liveweight of their lambs

“…In the present experiment, lambs born to the H treatment hoggets were 284 g heavier at weaning for each kilogram increase in liveweight at the time of breeding compared with the lambs born to the L treatment hoggets, which were higher than the 146 g/day reported by Kenyon et al (2006). This increased lamb liveweight could be due to superior milk production for a longer period of time and improved milk composition, although this is unknown and may require further investigation.…”

“…Increasing liveweight at the start of the breeding period has been shown to increase breeding activity (Moore et al 1978;Meyer & French 1979;Craig 1982;McMillan & Moore 1983), therefore potentially increasing the number of hoggets conceiving (Kenyon et al , 2006. However, in the present experiment, an average difference in hogget liveweight at the time of breeding of 6 kg did not affect the proportion of hoggets bred.…”

“…lamb birth weight. Kenyon et al (2006) reported lamb birth weight of single lambs to increase by only 5 g per kilogram increase in hogget breeding liveweight. The numbers used in the present experiment may not have allowed such a small difference to be detected (i.e.…”

“…In contrast, further studies Kenyon et al 2008b) of ad libitum pasture-fed hoggets achieving liveweight gains of 210Á230 g/day failed to repeat either the UK reports of a detrimental effect of high levels of feeding during pregnancy in hoggets or the results of Mulvaney et al (2008). It is possible that the abortions reported by Mulvaney et al (2008) were associated with Neospora caninum infection (West et al 2006;Howe et al 2008), although this is unknown. A clear difference between the UK housed studies and the NZ pastoral studies is hogget liveweight at the start of breeding: 44Á47 kg in the UK studies and 36Á38 kg in the NZ studies (Wallace et al 1996(Wallace et al , 1997a(Wallace et al , 1997bWallace 2000;Morris et al 2005;Kenyon et al 2008b;Mulvaney et al 2008).…”

“…Increased liveweight at the time of breeding is positively associated with the proportion of two-tooths and mature ewes displaying oestrus (Coop 1962;Adalsteinsson 1979;Knight 1980;Kenyon et al 2004c) and increases lambing percentage (Kenyon et al 2004b). In hoggets, it has similarly been reported that increasing liveweight at the time of breeding increases the proportion of hoggets cycling (Meyer & French 1979;Craig 1982), displaying oestrus (Allison et al 1975;Kilgour 1977, Moore et al 1978Moore & Smeaton 1980), conceiving (Kenyon et al , 2006 and hogget lambing percentage (Kenyon et al 2004b). …”