Breed, heterosis, and recombination effects for lactation curves in Brazilian cattle

Abstract

Breeding and geneticsFull-length research article Breed, heterosis, and recombination effects for lactation curves in Brazilian cattle ABSTRACT -The objective of this study was to estimate the breed, heterosis, and recombination effects on different components of the lactation curve of Girolando cattle. The dataset used consisted of 12,121 purebred cows of Holstein (H) and Gyr (G) breeds, and six H×G crossbred cows (Girolando). The model used presents random effects of herd and cow, regression coefficient associated with linear effect of proportion of H breed, regression coefficient associated with the linear effect of heterosis between H and G breeds, regression coefficient associated with the linear effect of recombination between H and G breeds, and random effect of residual. Dijkstra's (DJ), Nelder's (ND), Wilmink's (WL), and Wood's (WD) models were tested to fit production records of these different genetic groups. These models were then tested according to evaluation criteria of quality of fit (AIC, BIC, and RMSE), and the two best models (WD and WL) were chosen for estimation of 305-day milk yield (MY 305 ), peak yield, time to peak, and persistency of milk yield. The breed effect was significant for all traits and components of the lactation curve. The heterosis effect was significant for all traits, and was more significant for MY 305 (945.62±79.17 kg). Peak yield was the component of lactation curve that presented the most significant heterosis effect, partially explaining the heterosis effect (12 to 21%) found for MY 305 . The recombination effect was positive only for lactation period and time to peak of lactation in Girolando cows.

Dynamics of changes in the breed composition of pastoral and agro-pastoral cattle herds in Benin: implications for the sustainable use of indigenous breeds

“…To improve animal productivity, crossbreeding has been practiced worldwide for centuries ( Hill, 2014 ). The existence of numerous highly productive crossbreeds, such as Holstein-Friesian and Girolando, is well known ( Tadesse et al., 2010 ; Canaza-Cayo et al., 2016 ; Daltro et al., 2021 ). In Africa, several livestock production improvement programs have focused on crossing local breeds with exotic ones ( Leroy et al., 2016 ; Nyamushamba et al., 2017 ; Wilson, 2018 ).…”

Test day yield, lactation curve and production potential of Gir cattle under hot and humid conditions of Tamil Nadu

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