Optimising reproductive performance of beef cows and replacement heifers

Abstract

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.

Comparative study on production, reproduction and functional traits between Fleckvieh and Braunvieh cattle

“…In our study, age at first calving was significantly (p≤0.01) influenced by the breed, with Fleckvieh heifers being more precocious (−2.9 months) compared to those of Braunvieh breed (Table 1). Results are consistent with those reported by Diskin and Kenny [20] on the genetic effects on heifer puberty and subsequent reproduction outputs. Heritability estimates for age at puberty in Fleckvieh and Braunvieh breeds are in general considered to be moderate to high, with values of up to 0.40 [21], thus making this criterion suitable to selection.…”

Technologies that affect the weaning rate in beef cattle production systems

“…Weaning management used aims to reduce cow's nutritional requirements, thereby reestablishing the frequency of GnRH and LH pulses to achieve improved reproductive performance (Diskin and Kenny 2014). Temporary weaning (calf removal) was the only technology observed in our study that showed no difference between farmer clusters.…”

Invited

“…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. Diskin and Kenny (2014) outlined the following reproductive targets for a beef cow herd: 1) 365 d -calving to calving interval, 2) <5 % cows culled annually as barren, 3) >95% of cows calving to wean a calf, 4) Heifers calving at 24 months of age, 5) Compact calving with 80% of cows calved in 42 days, 6) Replacement rate 16-18%, 7) Sustained genetic improved of the cow herd for economically important traits relating to reproduction, calving ability and calf weaning weight, 8) Close alignment of calving date with onset of pasture availability in the spring.…”

“…As the calf is largely the sole output in beef cow enterprises, reproductive efficiency underpins profitability, irrespective of the system of production employed. 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.Diskin and Kenny (2014) outlined the following reproductive targets for a beef cow herd: 1) 365 d -calving to calving interval, 2) <5 % cows culled annually as barren, 3) >95% of cows calving to wean a calf, 4) Heifers calving at 24 months of age, 5) Compact calving with 80% of cows calved in 42 days, 6) Replacement rate 16-18%, 7) Sustained genetic improved of the cow herd for economically important traits relating to reproduction, calving ability and calf weaning weight, 8) Close alignment of calving date with onset of pasture availability in the spring.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 post partum interval for each successive calving, conception and pregnancy rate and ultimately manifested as length of inter-calving intervals and number of calves weaned over her lifetime (Diskin and Kenny, 2014). In calved heifers and mature cows, the onset of ovarian activity, post partum is a fundamental event dictating the calving interval.…”

“…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 post partum interval for each successive calving, conception and pregnancy rate and ultimately manifested as length of inter-calving intervals and number of calves weaned over her lifetime (Diskin and Kenny, 2014). In calved heifers and mature cows, the onset of ovarian activity, post partum is a fundamental event dictating the calving interval.…”