Milk yield and composition of Rambouillet ewes under intensive management

Abstract

The milk yield and composition from 45 Rambouillet ewes, 2–5 years of age, managed under intensive conditions at the Unidad Ovina, Facultad de Agronomı́a, Universidad Autónoma de San Luis Potosı́ were estimated. The ewes with single and twin lambs were assigned to two treatment groups: 6 and 8 weeks of lactation, which were the dates when the lambs were weaned. The field work lasted 12 weeks, from January to April, 1997. The ewes were hand-milked, without utilizing any stimuli to induce the milk-let-down. The ewes were milked twice every 7 days before weaning and daily after weaning. In both cases, total and daily milk yield were recorded. Milk was sampled during lactation (weeks 1, 3, 6, 8, and 12), and chemically analyzed using standard laboratory procedures. The correlations were estimated between daily milk yield and milk components (total solids, fat, protein, lactose and ash), as well as among milk components. The lactation week had a significant effect on total and daily milk yield, as well as on the milk components. The overall mean for total milk yield was 69±13.3 l per ewe, with a lactation period of 84 days and 822±278 ml per ewe for daily milk yield. Means for milk components were 16.7±2.1% for total solids, 5.6±2.1% for fat, 5.2±0.5% for protein, 4.5±0.4% for lactose and 0.91±0.06% for ash. Significant positive correlations were detected between milk yield and lactose, total solids and fat, total solids and protein, fat and protein, protein and ash, respectively. Significant negative correlations were found between milk yield and total solids, milk yield and fat, milk yield and protein, milk yield and ash, total solids and lactose, fat and lactose, protein and lactose, lactose and ash, respectively. It is concluded that Rambouillet ewes in Mexico have an important potential for milk production and the quality of its milk components suggests that this milk may be utilized in the cheese- and yoghurt-making industries in an attempt to provide additional returns from current sheep production systems.