Evaluation of Rumen-Protected Methionine Supplementation on Milk Production and Composition in Crossbred Dairy Sheep

In dairy sheep, optimum nutrition is required to maintain a positive energy and nitrogen balance, and therefore, achieve adequate performance levels. In this sense, supplemental rumen-protected methionine (RPMet) has been a nutritional strategy used to improve the availability of amino acids in sheep for milk production. The aim of the current study is to assess the effect of RPMet supplementation on the milk yield and milk composition of crossbred dairy sheep. Twenty F1 sheep (50% Pelibuey × 50% East Friesian) were randomly assigned to one of the following three treatments: C (control: 0 g/d), 3 g (3.0 g/d), or 6 g (6 g/d) of RPMet added to the basal diet from day 2 to 120 after lambing. Milk yield was significantly higher in sheep supplemented with 6 g of RPMet (<i>p</i> = 0.04) with a linear effect (<i>p</i> < 0.001). In relation to protein yield, the 6 g treatment showed the highest values (55.5 g/day) in comparison with the control (35.2 g/day) and 3 g (42.3 g/day) treatments. Also, lactose (<i>p</i> = 0.02) and non-fat solid yield (<i>p</i> = 0.03) were positively affected by the methionine supplementation. Our results suggest that methionine supplementation is an option to increase milk production, likely associated with the better availability of nutrients of dairy sheep farms using crossbred sheep in regions with an incipient dairy sheep industry.