The effect of breeding hoggets on lifetime performance

Abstract

The reported study involved mature ewes that had either been presented for breeding and had lambed as a hogget (MP), had been presented for breeding as a hogget but did not become pregnant (MNP) or were not presented for breeding as a hogget (NM). Their subsequent performance as mature ewes was examined. Although breeding as a hogget reduced (P B 0.05) two-tooth mating live weight and condition score in subsequent years, the differences were either smaller or not present at all (P !0.05). Breeding as a hogget increased (PB0.05) the number of foetuses per ewe lifetime (8.290.08, 7.090.13 and 7.190.12 for MP, MNP and NM respectively) but did not alter ewe (P!0.05) longevity. These results indicate that hogget breeding can be used as a management option to improve lifetime reproductive performance.Keywords: ewe lamb; hogget; breeding; reproduction; lifetime performance IntroductionIn New Zealand, approximately 30% of ewe lambs (7Á9 months of age; hoggets) are presented for breeding each year, but these ewe hoggets wean less than 4% of total lambs weaned in the national flock (MAF, 2010). These results indicate that increasing the percentage of ewe hoggets successfully bred and that rear a lamb to weaning is a means of increasing the national flock's productivity. A number of potential advantages of breeding ewe hoggets have been identified. These include higher net profits, improved utilisation of spring herbage, increased efficiency, early recognition of fertility potential, improved fertility level throughout the flock, increased rates of genetic gain and improved lifetime production of the ewe by breeding her at a younger age (Hight 1982;Kenyon et al. 2004b). However, Kenyon et al. (2004a) reported that the main reason farmers do not breed ewe hoggets is a perceived negative effect on breeding performance at 18Á19 months of age (twotooth). A negative effect on two-tooth performance may negate any potential positive effect of successful breeding as a hogget on lifetime performance. However, Dyrmundsson (1973) stated that breeding at a young age in wellmanaged and nourished ewes has no detrimental effects on subsequent reproductive efficiency and, in some studies, has enhanced subsequent fertility leading to an increase in lifetime performance. More recently, Kenyon et al. (2008) managed pregnant and non-pregnant ewe hoggets as one group and reported that ewe hogget breeding reduced two-tooth live weight, body condition score and reproductive performance. Under these conditions, it may be hypothesised that breeding ewe hoggets would have a negative effect on ewe lifetime productive performance. Therefore, the aim of the *Corresponding author.

Ewe Wastage in New Zealand Commercial Flocks: Extent, Timing, Association with Hogget Reproductive Outcomes and BCS

“…It has been reported that commercial farmers are concerned that hogget breeding results in increased risk of subsequent wastage; however, there was limited published data evaluating this [ 2 , 26 , 29 ]. In the present study, the association between hogget reproductive outcomes and subsequent wastage were evaluated for the Farm B cohort, as they were the only cohort that had both hoggets that were presented for breeding and hoggets that were not presented for breeding, and which did not cull any hoggets for poor reproductive performance.…”

“…Hogget breeding can be utilized in pastoral sheep production systems to increase the number of lambs produced each year, while concurrently increasing lifetime productivity [ 26 , 27 , 28 ]. However, there is a common concern among commercial farmers that hogget breeding may reduce ewe longevity, thereby increasing ewe wastage [ 29 ].…”

“…However, there is a common concern among commercial farmers that hogget breeding may reduce ewe longevity, thereby increasing ewe wastage [ 29 ]. Despite this, there are only few studies that have evaluated this [ 2 , 26 , 29 ] with further investigation needed.…”

1. Clean, Green, Ethical (CGE) Management: What Research Do We Really Need?

“…Conservative farmers often delay the mating of young females until they are 18-24 months old. This is a complex problem, with a mix of sociological and biological causes and solutions: i) Sociological: a major driver of the decision to delay first mating in young females is the belief by farmers that mating young animals impairs their performance in subsequent years; research shows that this is not that case (Kenyon et al, 2004(Kenyon et al, , 2011(Kenyon et al, , 2014; ii) Biological: in young females, first conception is limited by nutrition and growth (live weight, condition score). It is important to focus on ensuring ovulation, conception and neo-natal survival, bringing us back to 'focus feeding', ultrasound, birth-site management; iii) Genetical: in young sheep, it has been shown that genetic selection can be used to increase growth rate and thus advance the onset of puberty, even if the extra growth is primarily muscle (Rosales et al, 2013ab, 2014.…”

The Use of Concentration of Anti-Mullerian Hormone (AMH) as an Indicator of Reproductive Performance in Livestock Species

“…Replacement females can make up 25% of the breeding flock and their reproductive performance is generally lower than that of their flock mates (Quirke et al, 1977;Edwards et al, 2016). Additionally, replacement ewes that are successfully bred within their first year of age are more profitable and show greater lifetime reproductive performance than females bred to lamb at two years for the first time (Young et al, 2011;Kenyon et al, 2011;Kenyon et al, 2014).…”