The aim of this study was to investigate if river buffalo calves (Bubalus bubalis) have equal access to all cows and if milk is thus equally available to all of them. Suckling/allosuckling behaviour and weight gain (WG) of 29 calves (14 males and 15 females) was recorded with special consideration to their sex, birth order (BO) and age. Cows' nursing behaviour and milk production (MP) were also considered. While males tended to be born earlier than females during this study, this was not the trend in the overall herd records. The cows' MP was not effected by the calves' sex. However, bull-calves presented greater mean WG, and mean times spent in individual filial (IF) and in communal non filial (CNF) suckling than heifer-calves, which showed greater communal filial (CF) suckling than the former during the first 4 months of life. The WG was associated with IF for bull-calves (r=0.680 and 0.765, respectively, for the periods from birth to 4th and 8th months of age), and to CNF for heifer-calves (r=0.628, for the period from birth to 8th month). Results from multiple regression analysis showed independent effects of each suckling category on the calf WG, and such effects were variable according to the calf's sex. BO was negatively correlated to calves' WG (bull-calves: rs=-0.873 and -0.799, from birth to 4th and 8th months, respectively; heifer-calves: rs=-0.531 from birth to 4th month). Specifically for bull-calves, there was a positive correlation between BO and MP (rs=0.528 and 0.633, from birth to 4th and 8th months of age, respectively). The correlation between BO and IF was negative in both sexes, indicating that calves that were born early had more opportunities to suckle individually from their mothers. For heifer-calves, BO was positively correlated with CF (2 periods), and negatively with CNF (from birth to 8th month of age), suggesting that heifer-calves were most often accompanied by other calves during suckling when they were born later. The data taken together indicate that sex and/or BO influenced decisively social interactions during suckling, promoting differential development among the calves.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||Departamento de Zootecnia, Faculdade de Ciencias Agrarias e Veterinarias, Universidade Estadual Paulista, 14870-000 Jaboticabal, SP, Brazil.|
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