Body weight of dairy heifers is positively associated with reproduction and stayability

Abstract

This study investigated the relationships between body weight (BW) and stayability, and BW and calving pattern, of 189,936 New Zealand dairy heifers. Heifers were classified into 5 breed groups: Holstein-Friesian (F), Holstein-Friesian crossbred (FX), Jersey (J), Jersey crossbred (JX), and Holstein-Friesian × Jersey crossbred (FJ). Body weight was predicted using Legendre polynomials at 6, 12, and 15 mo of age, and we analyzed their relationships with stayability, calving rate, and re-calving rate over the first 3 calvings. Approximately 92% of heifers calved for the first time at age 2 yr, 76% a second time at 3 yr, and 61% a third time at 4 yr. Heifers that were heavier were more likely to remain in the herd for first, second, and third calving compared with heifers that were lighter. Furthermore, we found positive curvilinear relationships between prebreeding BW and reproductive performance of dairy heifers. Heifers that were heavier at 6, 12, and 15 mo were more likely to calve early for first calving compared with heifers that were lighter, regardless of breed group. In addition, we found a large range in BW where the probability of calving or re-calving early was high. For example, FJ heifers that were between 255 and 396 kg at 15 mo of age had 21-d calving and re-calving rates above 75 and 70%, respectively. For second and third lactations, however, heifer pre-breeding BW showed only small effects on the 21-d calving and recalving rates. For heifers that were at the heaviest end of the BW range in the current study, slight declines in stayability and reproductive performance occurred, compared with heifers in the mid-range of BW. Consequently, for heifers that were above average in BW, the benefit of increasing BW before first breeding would be small and might even result in slight declines in stayability and reproductive performance. For heifers that were below average in BW, considerable beneficial effects on stayability and reproductive performance are predicted as a result of improving rearing practices to produce heavier heifers throughout the pre-breeding rearing phase.

Analysis of Longevity Traits in Holstein Cattle: A Review

“…Jenko et al, 2013 Stayability A measure of cow survival that does not require recording of cull data. Handcock et al, 2020 The probability of a cow remain in the herd enough time to raise a certain number of calves that pay for her development and maintenance costs. Costa et al, 2020 The ability of the cow to calve at least three times until 76 months of age.…”

Heifers with positive genetic merit for fertility traits reach puberty earlier and have a greater pregnancy rate than heifers with negative genetic merit for fertility traits

“…However, longterm benefits have also been reported. Heifers that are well grown, and heifers that get pregnant early in the breeding season, calve earlier and have improved lifetime production and reproduction (Pryce et al, 2007;Wathes et al, 2014;Dennis et al, 2018;Handcock et al, 2020). The extent and consistency of benefits under commercial conditions requires a larger data set to quantify the benefits under commercial environments.…”

Relationship of body weight at first calving with milk yield and herd life

“…However, other studies have indicated that underconditioned heifers also have poor reproductive outcomes. A recent study reported an intermediate optimum for the relationship of BW at 15 mo of age with the proportion of animals that calved within the subsequent calving window (Handcock et al, 2020). Cows genetically inclined toward low BW during peak lactation also have poorer fertility due to an inability to maintain body condition (Pryce et al, 2001;Frigo et al, 2010).…”