Influence of age at first calving in a continuous calving season on productive, functional, and economic performance in a Blonde d’Aquitaine beef population1

Abstract

The lifetime production of 7,655 cows with known age at first calving and a total of 27,118 parity records from 301 purebred Blonde d'Aquitaine herds were used to demonstrate the economic benefits of 2 yr of age at first calving. Ages at first calving ranged from 20 to 48 mo, and cows were divided into 5 calving groups, starting with early calving from age 20 to 27 mo up to late calving from age 40 to 48 mo. The information was gathered into 2 data sets, one for only primiparous cows and the second for all cows. The traits analyzed in this study were grouped as functional, linear type, and production traits. Functional traits were calving interval, calving ease, and number of calvings. Skeletal, muscle, and functional appraisal were included as linear type traits. The production traits studied were BW and weaning weight, carcass growth, and conformation of the offspring. The only significant traits found in primiparous cows were late age at first calving, which resulted in heavier BW calves, and early age at first calving, which resulted in calves with greater carcass conformation scores. Age at first calving was found to be significant only in its effect on BW and the number of calvings over a cow's lifetime, with lighter calves for early age at first calving. Heritability for age at first calving was 0.17. Genetic correlation of age at first calving with direct calving ease was positive (0.27) and that with maternal calving ease was negative (-0.39). Age at first calving showed a negative genetic correlation with lifetime number of calvings (-0.29) and a positive correlation with calving interval (0.14). Correlations with production and type traits were low, except for skeletal development (-0.29). Based on phenotypic and genetic analysis, there is a tendency for early-calving cows to produce a greater lifetime number of calves with less muscle but good carcass growth. Age at first calving affected the number of heifers in the herd, replacement rate, and number of animals slaughtered each year. Shortening the age at first calving from 3 to 2 yr led to a reduction of heifer feeding cost of US$21.24 (17.7€), a reduction of production cost of $26.52 (22.1€), and a profit increase of $25.80 (21.50€) per slaughtered animal per year over lifetime cow production.

Genetic Parameters for Age at First Calving and First Calving Interval of Beef Cattle

“…Moreover, AFC is a complex trait encompassing puberty and the ability to conceive, gestate, and deliver a calf [ 6 ]. Low AFC increases the productivity rate and at the same time decreases the replacement rate [ 7 ]. A calving interval of 365 days is reported as a target, but the focus should be on shortening the nonproductive periods to avoid economic losses because the length of the calving interval has a direct connection with the number of calves born annually [ 7 ].…”

Escore visual como uma ferramenta eficiente para identificação de bovinos precoces

“…A bovinocultura de corte brasileira passou por grandes modificações nos últimos anos, de 1995 a 2016 o rebanho bovino cresceu 38%, saindo de 153,1 milhões para 220,9 milhões de cabeças (IBGE, 2018). O aumento substancial no efetivo bovino e na eficiência de produção nos últimos anos ocorreu graças a adoção e melhoria dos processos tecnológicos; entre elas a seleção de indivíduos com maior mérito genético (BORBA et al, 2016;CARVALHO et al, 2019), permitiu uma redução na idade ao primeiro parto e no ciclo de produção (GUARINI et al, 2015;FERNANDES et al, 2016;PAREDES et al, 2018).…”

“…Conceitualmente, "Precoce'' é o animal cujo esqueleto se completa antes da idade comum à sua espécie (OWENS et al, 1993). Quanto mais rápido o animal chegar ao peso adulto padrão da raça, mais curto será o ciclo de produção e maior a possibilidade de reduzir os custos de manutenção na propriedade (PAREDES et al, 2018). Desse modo, a seleção de animais com base na precocidade auxilia na identificação de animais mais eficientes e adaptados aos sistemas de produção.…”

Identification of genomic regions related to age at first calving and first calving interval in water buffalo using single‐step GBLUP

“…Reproductive traits are important for meat and dairy production systems, with direct impacts on the farm's profitability (Ettema & Santos, 2004; Lópes‐Paredes, Pérez‐Cabal, Jiménez‐Montero, & Alenda, 2018), a fact justifying the inclusion of these traits as selection criteria in breeding programs. Age at first calving (AFC) and first calving interval (FCI) are the main indicator traits of reproductive efficiency in domestic herds.…”