Genetic parameters for calving difficulty using complex genetic models in five beef breeds in Australia

Abstract

Data on Angus (ANG), Charolais (CHA), Hereford (HER), Limousin (LIM) and Simmental (SIM) cattle were used to estimate genetic parameters for calving difficulty (CD), birthweight (BWT) and gestation length (GL) using threshold-linear models and to examine the effect of inclusion of random effect of sire × herd interaction (SxH) in the models. For models without SxH, estimated heritabilities for direct genetic effect of CD were 0.24 (±0.02), 0.22 (±0.04), 0.31 (±0.02), 0.22 (±0.04) and 0.17 (±0.01) for ANG, CHA, HER, LIM and SIM, respectively, whereas maternal heritabilities ranged from 0.13 to 0.20. Estimated heritabilities for direct genetic effect of BWT were 0.38 (±0.01), 0.37 (±0.03), 0.46 (±0.01), 0.35 (±0.02) and 0.36 (±0.01) for ANG, CHR, HER, LIM and SIM, respectively, whereas maternal heritabilities ranged from 0.08 to 0.11. Estimated heritabilities for direct genetic effect of GL were 0.59 (±0.02), 0.42 (±0.04), 0.50 (±0.03), 0.45 (±0.04) and 0.42 (±0.03) for ANG, CHR, HER, LIM and SIM, respectively, whereas maternal heritabilities ranged from 0.03 to 0.09. Genetic correlations between direct genetic effects of CD with BWT were highly positive and with GL were moderately positive for all five breeds. Estimated genetic correlations between direct genetic effects and maternal genetic effects (rdm) ranged across the five breeds from –0.40 (±0.05) to –0.16 (±0.02), –0.41 (±0.03) to –0.27 (±0.08) and –0.47 (±0.10) to –0.06 (±0.12) for BWT, GL and CD, respectively. Fitting SxH interaction as additional random effect significantly increased the log-likelihood for analyses of BWT, GL and CD of all breeds, except for GL of CHA. The estimated heritabilities were less than or equal to the estimates obtained with models omitting SxH. The rdm increased (i.e. became less negative) for BWT, GL and CD of all five breeds. However, the increase for GL was not substantially high in comparison to the increase observed for BWT and CD. Genetic parameters obtained for BWT, GL and CD, by fitting SxH as an additional random effect, are more appropriate to use in the genetic evaluation of calving ease in BREEDPLAN.

Sire Effects on Birth Weight, Gestation Length, and Pre-Weaning Growth of Beef-Cross-Dairy Calves: A Case Study in New Zealand

“…The genetic correlation between birthweight and gestation length was negative, indicating that selecting for shorter gestation is likely to result in increased birthweight, in the absence of selection pressure on other traits. This negative correlation conflicts with previous reports for both dairy-breed and beef-breed cattle, (genetic correlations range 0.15-0.63 [7][8][9][10][11][12][13]), and indicates further investigation using a larger population with known maternal pedigree, and the inclusion of purebreds as well as crossbreds, would be worthwhile. In contrast, the moderate positive phenotypic correlation between birth weight and gestation length, is consistent with other studies which report a positive correlation [8,10,13,35].…”

“…The variation among the sires for progeny birth weight indicated that choice of sire could change birth weight by as much as 8 kg in spring-calving herds, even when selecting sires from within the same breed. The lighter calves from Angus bulls than from the Hereford bulls used in this case study was consistent with previous literature that reported a 1.4-3.5 kg greater birth weight for Hereford than Angus calves [12,[19][20][21][22]. It should be highlighted that the current study was not a breed comparison, because individual bulls were selected to achieve a spread of EBV and were not a random sample from the breed, and, therefore, may not accurately represent the breed as a whole.…”

“…More Angus bulls than Hereford bulls used in this study produced calves with shorter gestation length than the dairy average gestation length (<281 days; 25 Angus bulls versus 8 Hereford bulls). The difference in gestation length of calves between sirebreeds in this analysis is consistent with the literature, which reports that straight-bred or cross-bred Angus calves have a shorter gestation than Hereford breed calves (range 1-5.4 days) [12,13,[20][21][22]27,29,30]. A shorter gestation length benefits the dairy industry by decreasing the calving interval, which would reduce the calving spread, and due to calving earlier in the season, there is the potential for cows to have more days in milk [18,[31][32][33][34].…”

“…Birth weight is positively genetically correlated with weaning weight, and gestation length [7][8][9][10][11][12][13]. The ideal for beef bulls used over dairy cows is low birth weight, short gestation, and high weaning weight or rapid pre-weaning growth.…”

Genetic evaluation of gestation length and its use in managing calving patterns

“…The negative genetic correlations between direct and maternal genetic effects observed in the current study is consistent with several others (Cervantes et al, 2010;Jeyaruban et al, 2015;Johanson et al, 2011) and could be a mechanism to keep GL of cows within a narrow range (i.e., SD). Consequently, it is common for genetic correlations between direct and maternal effects to be negative (McClintock, 2004;Johanson et al, 2011).…”