Milk Production of Sarda Suckler Cows with Different Calving Period

The study explored the relationship between the performance of calves and calving season in a Mediterranean rangeland-based beef livestock system. Twenty multiparous Sarda cows, grazing on a natural pasture, with two distinct calving periods (group A, 11 animals, calving date 15/10/2016 ± 16 (means ± s.d.), and group W, nine animals, calving date 26/01/2017 ± 11) were used. Meteorological data, herbage quality, daily milk yield (DMY), total milk yield (TMY), body weight (BW) of cows and calf, body-weight daily gain (ADG) of calves, body condition score (BCS) and calving interval (CI) of cows were assessed. A mixed-effects model was used to DMY and ADG data while TMY, BCS, weaning weight (WW) and CI data were analyzed by a linear model. The most determining factors in the DMY and ADG were detected by means of partial least square regression (PLSR) procedure. Group W showed higher DMY (6.5 ± 0.3 kg/d vs. 4.5 ± 0.3 kg/d, p < 0.001) and TMY (1,189 ± 70 kg vs. 830 ± 60 kg, p = 0.002) than Group A, but this did not result in a greater ADG of calves (Group A: 0.83 ± 0.04 kg/d/animal and Group W: 0.99 ± 0.09 kg/d/animal, p-value not significant) or WW when adjusted for their age (Group A: 216 ± 14 kg/animal and Group W: 250 ± 22 kg/animal, p-value not significant). In contrast, the WW actually measured were higher in Group A than in Group W (257 ± 7 kg vs. 175 ± 8 kg, p < 0.001). The Group W cows experienced a minor CI than Group A cows (288 ± 13 d vs. 320 ± 8 d, p = 0.04). The results of PLSR suggest that the factors with utmost importance for both DMY and ADG were the age and the body-weight of cows, highlighting the excellent maternal ability of Sarda breed and its good adaptation to environment.