Effect of dietary crude protein source on hormone and follicle characteristics in beef heifers1

Martin, Jeremy L.; Larson, D. M.; Stroh, Hans-Jürgen; Cupp, Andrea S.; Funston, R. N.

doi:10.2527/jas.2009-2236

Cited by 2 publications

(1 citation statement)

References 22 publications

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“…Scholljegerdes et al (2009) recorded lower tissue concentrations of LH and IGF-1, follicle numbers, systemic oestradiol and overall conception rate in beef cows supplemented with high-linoleate safflower seeds compared with unsupplemented controls. SimiIarly, Martin et al (2010) observed no advantage of supplementing heifers with soya beans in either productive or reproductive efficiency. In a series of experiments conducted with beef heifers, Childs et al (2008aChilds et al ( , 2008bChilds et al ( and 2008c failed to establish any positive effects of enriching diets with rumen bypass n-3 fatty acids on a range of reproductive variables including steroid concentrations, follicle size and on the quantity or quality of embryos, following superovulation.…”

Section: Nutritional Effects On Conception and Pregnancy Ratementioning

confidence: 98%

Optimising reproductive performance of beef cows and replacement heifers

Diskin

Kenny

2014

Animal

104

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A reproductively efficient beef cow herd is fundamental to meeting the protein and specifically, red meat demand of an ever increasing global population. However, attaining a high level of reproductive efficiency is underpinned by producers being cognisant of and achieving many key targets throughout the production cycle and requires significant technical competency. The lifetime productivity of the beef bred female commences from the onset of puberty and will be dictated by subsequent critical events including age at first calving, duration of the postpartum interval for each successive calving, conception and pregnancy rate and ultimately manifested as length of intercalving intervals and number of calves weaned over her lifetime. Puberty in heifers is a consequence of the interactive effects of genetics and both pre-and post-weaning nutrition. Early onset of puberty is essential to achieving the first main reproductive target for beef cow herds; first calving at 2 years of age. In calved heifers and mature cows, the onset of ovarian activity, postpartum is a key event dictating the calving interval. Again, this will be the product mainly of prepartum nutrition, manifested through body condition and the strength of the maternal bond between cow and calf, though there is increasing evidence of a modest genetic influence on this trait. Following the initiation of postpartum ovarian cyclicity, conception and subsequent pregnancy rate is generally a function of bull fertility in natural service herds and heat detection and timing of insemination in herds bred through artificial insemination. Cows and heifers should be maintained on a steady plane of nutrition during the breeding season, but the contribution of significant excesses or deficiencies of nutrients including protein and trace elements is likely to be minor where adequate pasture is available. While, increased efforts are being made internationally to genetically identify and select for more reproductively efficient beef cows, this is a more long-term strategy and will not replace the need for a high level of technical efficiency and management practice at farm level.

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