Nutritional efficiency of feed-restricted F1 Holstein/Zebu cows in early lactation.

The quantitative feed restriction of lactating cows has been used in intensive production systems as a strategy to reduce production costs. However, the effects of this restriction in F1 Holstein/Zebu cows are unclear. The objective of this work was to evaluate the effect of quantitative feed restriction on nutrient intake and digestibility, nitrogen balance, feed efficiency, feed behavior, and productive performance in F1 Holstein/Zebu cows during early lactation. Sixty F1 Holstein × Zebu cows were used at the stage of initial lactation (50 ± 13 days of lactation), and they had an initial body weight (BW) of 482 ± 43 kg. The experimental arrangement adopted was a completely randomized design, with five feed restriction levels (3.39, 2.75, 2.50, 2.25, and 2.00% of BW) and 12 cows in each treatment group. In the short term (63 days), there were reductions of 45.9% and 47.2% in dry matter intake (P < 0.01) and crude protein (P < 0.01), respectively, when the diet supply was limited from 3.39% BW to 2.00% of BW. There were declines in intake of ether extract (P < 0.01) and nonfibrous carbohydrates (P < 0.01), but there was no change in daily milk production (P = 0.44) nor the daily milk production corrected to 3.5% fat (P = 0.12); the averages were 14.01 kg/day and 13.25 kg/day, respectively. Considering the lower body weight loss, feed restriction is recommended up to 2.5% of the BW.

Nutritional and productive parameters of Holstein/Zebu cows fed diets containing cactus pear

Objective: This study ascertained effects of cactus pear in association with different roughage in the diet of F1 Holstein/Zebu cows on intake, nutrient digestibility, nitrogen balance, ingestive behavior and performance. Methods: Eight cows with 72 ± 11 days of lactation were used. The experimental design was simultaneous in two 4 x 4 Latin squares. Four experimental diets were used: Diet 1 - sorghum silage as exclusive roughage; Diet 2 - sorghum silage associated with cactus pear in a proportion of 50% of the roughage (dry basis); Diet 3 - elephant grass (Pennisetum purpureum cv. Roxo) as exclusive roughage; Diet 4 - elephant grass associated with cactus pear in a proportion of 50% of the roughage. The roughage:concentrate ratio was 75:25. Dry matter intake (P = 0.01) was higher with sorghum silage. Results: There were differences in dry matter intake (P = 0.01), crude protein (P <0.01), ether extract (P = 0.01), non-fibrous carbohydrates (P <0.01) and total digestible nutrients (P = 0.01) among the diets. Cactus pear in the diet reduced water intake by 44.52% (P < 0.01). The nitrogen balance was 59.71% and 27.49% lower in animals treated with exclusive sorghum silage and sorghum silage associated with cactus pear in relation to diets with elephant grass and elephant grass associated with cactus pear, respectively (P < 0.01). The diets did not influence the milk production (P = 0.70), 3.5% fat corrected milk production (P = 0.72) or feed efficiency (P = 0.61). Conclusion: The association of cactus pear with sorghum or elephant grass silage does not alter milk production, reduces the intake of dry matter and water and improves the digestibility of nutrients.