Abstract: The purpose of this study was to investigate the effects on cow performance and blood biochemical and immune indicators in the perinatal period, of different proportions of millet straw and Leymus chinensis, added to a constant base of 16% concentrate and 24% whole-plant maize silage in a total mixed ration (TMR) diet fed to Holstein cows in the early dry period. Forty-five Holstein cows with similar body weight, parity, body condition and calving date in the early dry period were selected and randomly divided into 3 groups: A, B and C, fed with a TMR diet comprising concentrate, whole-plant corn silage, millet straw and L. chinensis in ratios of 16∶24∶30∶30, 16∶24∶45∶15 and 16∶24∶60∶0, respectively. The three groups of cows were transferred to a perinatal herd two weeks before calving, and after transfer were fed the same diets in the pre-perinatal and post-perinatal period. The whole trial lasted for 88 days. The results showed that: 1) Compared with group C, the dry matter intake (DMI) of group B was increased by 10.46% (P<0.05), 7.79% (P<0.05) and 5.65% (P<0.05), respectively, at week 1, week 2 and week 3 postpartum. In addition, at 1 week postpartum, the body condition scoring of cows in group B was 6.60% higher than that of group C (P<0.05), while at 2 and 3 weeks postpartum BCS was 9.06% higher (P<0.05). 2) There was no significant difference between the 3 test groups (P>0.05) in the birth weight of calves. The Immunoglobulin (Ig) G content of colostrum in group A and B was, respectively 10.82% (P<0.01) and 18.07% (P<0.01) higher than that in group C. 3) Compared with group C, the milk yield of group B was increased by 9.00% (P<0.05), the non-fat solid content by 2.83% (P<0.05), the milk protein content by 10.59% (P<0.05) and the lactose content by 5.64% (P<0.05). However, there was no significant difference in milk fat percentage and milk urea nitrogen among the test groups (P>0.05). 4) On the day of delivery and 21 days after delivery, the serum triglyceride levels of group B cows were significantly lower than those of groups A and C (P<0.05), the blood glucose levels of group B were significantly higher than that of group A and group C (P<0.05), and serum urea nitrogen and insulin levels in group B were significantly lower than those in group C (P<0.05). Also, insulin-like growth factor and total protein levels in group B cows were significantly higher than those in group C (P<0.05). At 7 days before delivery and on the day of calving, serum IgA, IgM and IgG in group B cows were significantly higher than those in group C (P<0.05). At 21 days postpartum, serum IgM and IgG levels in group B cows were significantly higher than those in group C (P<0.05). At day 7 before and on the day of calving, leptin levels of group B cows were significantly higher than group C cows, while the serum non-esterified fatty acid level of group B was significantly lower than that of group C (P<0.05). At day 7 before calving, on the day of calving and at day 21 after the calving, the cholesterol levels of group B cows were significantly lower than those of group C (P<0.05), while the serum albumin levels of group C cows were significantly higher than for group C, and the AST and ALT levels of group B were significantly lower than those of group C (P<0.05). There was no significant difference in β-hydroxybutyric acid between the test groups (P>0.05). In summary, the diet composition and nutrient level in the early dry period affected cow body metabolism and production performance in the perinatal period. Under the conditions of this experiment, the optimal TMR formulation for Holstein cow diet in the early dry period was a mix of concentrate, whole plant corn silage, millet straw and L. chinensis in the ratio 16∶24∶45∶15.

Key words: Chinese Holstein cows, millet straw, Leymus chinensis, dry period, perinatal period, production performance