The prepartum supplementation of dairy cows with β-carotene was evaluated. Cows were blocked by parity and expected calving date and assigned to a treatment: β-carotene (1.2 g/cow per d) or control (no supplementation). The same total mixed ration batch was offered to all cows, and β-carotene was top dressed to individual cows once per day. The data set contained 283 Holsteins that received a treatment for >14 d (29.1±6.9 d). Frequency distributions were analyzed with the GENMOD procedure of SAS using logistic regression for binomial data. Continuous variables were analyzed with the MIXED procedure of SAS. Within parity, nonparametric estimates of the survivor function for reproductive variables were computed using the product-limit method of the Kaplan-Meier method with the LIFETEST procedure of SAS. Plasma β-carotene concentration before supplementation was similar between supplemented and nonsupplemented cows (2.99µg/mL) and peaked at 3.26±0.175µg/mL on d -15±2.4 precalving for supplemented cows (2.62±0.168µg/mL for control). Colostrum density, milk yield, and milk composition were similar between treatments. β-Carotene tended to increase milk protein content from 2.90 to 2.96% and to decrease the proportion of primiparous cows with a milk fat to protein ratio >1.5 from 22.6 to 6.4%. The proportion of primiparous and multiparous cows with difficult calving, metritis, progesterone >1 ng/mL at 21 d and at 42 d in lactation, % conception at first service, and % pregnancy at 90 and 150 d in lactation were similar between treatments. A trend for decreased incidence of somatic cell count >200,000 cells/mL was present in multiparous cows supplemented with β-carotene (38.9% vs. 28.1%). β-Carotene was associated with a reduction in the proportion of multiparous cows with retained placenta 12 h postpartum from 29.9 to 21.7%; time of placenta release was 392 min (340 to 440) for β-carotene and 490 min (395 to 540) for control (median and 95% confidence interval). For primiparous cows, placenta release was not affected by β-carotene (incidence was 15.4%). The intervals from calving to first estrus, to first service, and to conception were not affected by β-carotene supplementation in either parity. However, independent of treatment, cows with improved reproductive efficiency had increased postpartum β-carotene concentration in plasma. The prepartum supplementation of β-carotene increased plasma concentration around calving. No response in milk yield or reproductive performance was detected. Beta-carotene supplementation was associated with a lower incidence of retained placenta in multiparous cows.

The aim of this study was to evaluate the effects of replacing Tifton-85 hay (0, 20, 40, 60 and 80 % on a dry matter basis) with water hyacinth hay (Eichhornia crassipes) on intake and digestibility of nutrients, feeding behaviour, rumen and blood parameters of sheep. Five uncastrated male sheep, cannulated in the rumen, with an average body weight of 40 kg were assigned in a 5 × 5 Latin square design. The water hyacinth hay contained 870 g/kg dry matter (DM), 159 g/kg crude protein (CP), 547 g/kg neutral detergent fibre (NDF) and 461 g/kg total digestible nutrients (TDN). The DM intake and digestibility of NDF and non-fibre carbohydrates (NFC) were linearly reduced by replacing the Tifton-85 hay with water hyacinth hay. Similarly, there was a linear reduction of rumination time and efficiencies of feeding and rumination of DM and NDF. The concentrations of urea, glucose, AST and GGT in blood plasma were not changed by replacing the Tifton-85 hay with water hyacinth hay. Although water hyacinth hay reduced the intake and digestibility of some nutrients, the Tifton-85 hay replacement could be economically advantageous for sheep feeding.

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