Effect of diet on energy balance and reproductive performance in primiparous Holstein and SRB cows

• The objective of this study was to investigate the effect of diet on energy balance (EB) and reproductive performance in primiparous Holstein and Swedish Red cows (SRB). A total of 44 cows (22 Holstein, 22 SRB) kept in a loose housing system were included in the study. The control group (HE, n = 23) was fed a diet for high producing cows (target 35 kg/day Energy-Corrected Milk, ECM). The lower feeding intensity (LE, n = 21) was achieved by giving -50% concentrate to target 25 kg/day ECM. Diets were implemented one month before calving and cows were followed from calving to 17 weeks postpartum (pp). The weekly EB was calculated using NorFor. Mixed linear models were used to analyze data (SAS 9.3; proc mixed). There was a large individual variation in EB, however Holstein cows tended to have lower mean EB than SRB cows (-4.67 ± 15.7 MJ vs 0.69 ± 14.2 MJ; p = 0.078). In early pp (within days 5 and 12) Holstein cows were in a deeper negative EB than SRB cows (p < 0.001), tended to be lower between Days 13 and 20 postpartum (p = 0.08), subsequently the curves met at Day 98. There was a tendency for a lower EB in the LE diet group between Days 45 and 52 pp (p = 0.07). No significant effects of diet or breed were found on % Pregnant at 1st AI. To conclude, despite trends were found for differences in EB between HE and LE diet groups, the stronger Negative EB status in the LE diet group was not associated with lower reproductive performance.

Ämnesord

LANTBRUKSVETENSKAPER  -- Bioteknologi med applikationer på växter och djur -- Genetik och förädling inom lantbruksvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agricultural Biotechnology -- Genetics and Breeding in Agricultural Sciences (hsv//eng)

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