Milk Production of Sarda Suckler Cows with Different Calving Period

摘要

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.