Body weight and measures of purebred Holstein and crossbred cows from Viking Red, Montbéliarde and Holstein sires

Crossbreeding in dairy cattle has become of interest for commer- cial dairy farms to enhance fertility, health and longevity of cows, and most studies focussed on these traits, as well as on effects on milk yield. Conversely, effects on production efficiency have been scarcely investigated. Body weight and measures can be used as scaling factors for computing efficiency indicators, and for estimating energy requirements of cows. This study aimed to compare the purebred Holstein (Ho) with crossbred cows pro- duced within a rotational crossbreeding scheme involving Viking Red (VR), Montbéliarde (Mo) and Ho sires on body traits and to develop prediction equations for estimating the body weight (BW) of cows. BW, body condition scores (BCS) and body measures were taken on 225 cows kept in a commercial dairy farm (number of sampled cows was 60 for purebred Ho and ranged between 15 and 35 within each breed combination). BW averaged 664 ± 88 kg and was similar for Ho and crossbreds, but Ho were (p<.05) taller, longer in body, had greater heart girth and lower BCS (3.03 vs. 3.34, p<.05) than crossbred cows. For developing prediction equa- tions to estimate BW, records available were divided into a cali- bration (150 cows) and a validation (75 cows) data set. The former was used to run different prediction models of BW, using the regression procedure of SAS and including as independent variables BCS and body measures alone or combined with parity and days in milk class or breed effects or both; the latter was used for validating the reliability of models developed on an indepen- dent data set. Determination coefficients (R2) of regressions for 4 models developed were constantly above 0.80. The model selected included breed effects (VR and Mo, with respect to Ho, which was included in the intercept), heart girth, body length and BCS. R2 of the model was 0.83, with a root mean square error of 33.92 kg. Bias (the average difference between predicted and observed BW) and precision (the standard deviation of bias) was −5.7 and ±31.55 kg, respectively. The results obtained from this study provided a new insight into the phenotypic variation of crossbred cows obtained from a 3 breed rotational crossbreeding scheme. Besides, this prediction equation, as a simple and reli- able method to estimate the BW of crossbred cows, can be used in further studies aimed to compare the performance of pure Ho and crossbred cows in term of production efficiency. Acknowledgements The research was funded by University of Padova. Appreciation is expressed to Genesi Project Srl (Castelnovo Sotto, RE, Italy) and ProCross and to La Corte (ALBALAT Soc. Coop. Agr., Carpi, MO) farm.