Performance And Composition Of Milk Fat Of Holstein Cows Fed Whole Cottonseed During Early Lactation

Eight Holstein cows in early lactatation with similar milk yield, parity and time of parturition, were selected respectively in a replicated 4×4 Latin square design, and were assigned randomly into 4 groups each with 2 replicates to study the performance and composition of milk fat of Holstein cows fed whole cottonseed(WCS). Treatments involved WCS with 0(group A/control group), 5%(group B), 10%(group C), 15% (group D)in concentrate(DM base) respectively. All the cows were fed with the same concentrate of the same nutritive concents. The main results were showed as follows: the cows fed WCS tended to yield more milk and FCM than the cows without feeding WCS. Group B, C, D increased milk with 0.9kg/d, 1.16kg/d and 1.08kg/d(P＞0.05) respectively compared with the control group. Dried material intake(DMI) was improved by feeding WCS. DMI of group B, C, D was 18.95kg/d, 19.99kg/d, 20.52kg/d and 21.52kg/d respectively. DMI of group C increased 1.57kg/d(P＜0.05)compared to the control group. DMI of group D increased 2.57kg/d (P＜0.01) compared to the control group. Feed efficiency was reduced to some extent by feeding WCS(P＞0.05). The rate of milk fat in the four groups was 3.37%, 3.48%, 3.98% and 3.96% respectively. The rate of milk fat of Group C and D was significantly increased compared to the control group.Milk protein, lactase, SNF percentage and the apparent digestibility rate of crude protein were not significantly different among treatments(P＞0.05). The apparent digestibility rate of crude fat of group B was the highest among all the groups, but no significant difference among groups (P＞0.05). The apparent digestibility rate of NDF was 38.94%, 40.32%, 42.23% and 39.67% respectively. The rate of group C was the greatest among all the groups (P＜0.05). The apparent digestibility rate of ADF was not significantly different among groups(P＞0.05). The contents of cholesterol of the four groups were 194.90mg/dl, 187.50mg/dl, 174.64mg/dl, 184.83mg/dl respectively. WCS supplementation in diets could reduce the content of cholesterol. Group C was significantly reduced than the control group(P＜0.01). The different levels of WCS in diets affect the content of total albumin, the contents of total albumin of group C and D increased 0.35g/dl(P＜0.05) and 0.32g/dl(P＜0.05) compared to the control group. The contents of albumin and serum glucose were not significantly different among treatments(P＞0.05). The different levels of WCS in diets affect the contents of BUN. The contents of BUN of group B and C reduced 0.47mg/dl(P ＞0.05) and 0.62mg/dl (P＞0.05) compared to the control group, but the contents of BUN of group D increased 2.22mg/dl(P＜0.01) compared to group A. WCS supplementation in diets affected the content of MUN, the content of group B, C reduced 0.75mg/dl(P＞0.05), 0.83mg/dl(P＞0.05) compared to the control group, but the content of group D increased 1.49mg/dl(P＜0.05) compared to the control group. The cows fed WCS reduced the percentage of SFA in milk fat than the cows without feeding WCS. Group B and C reduced the percentage of SFA about 10%(P＜0.01) compared to the group. The percentage of MUFA of group C was higher than the other groups(P＜0.05). WCS supplementation in diets could increase the percentage of PUFA in milk fat, the percentage of group B, C, D improved the percentage of PUFA with 7.55%(P＜0.01), 4.84%(P＞0.05), 8.93%(P＜0.01) compared to the control group. The percentage of short chain fatty acids were 33.66%TFA, 28.59%TFA, 30.36%TFA and 36.14%TFA. WCS supplementation in diets reduced the percentage of medium chain fatty acids, group D reduced 9.13% compared to the control group(P＜0.05). WCS supplementation in diets significantly improved the percentage of long chain fatty acids in milk fat, the percentage of group B significantly increased compared to control group(P＜0.01) respectively. The cows fed WCS increased the levels of free gossypol in serum and milk than the cows without feeding WCS. The diets with 5% and 10% WCS improved the economic profit with 0.13yuan/head/d and 4.5 yuan/head/d respectively, but diet with 15% WCS reduced the economic profit with 2.07 yuan/head/d.Analysis indicated that 10% WCS in diet was the optimal dosage in early lactation diet and may be regard as the reference in practice.