Milk yield of nursing and dairy mares

This paper reviews main characteristics of milk yield in nursing and dairy mares, and the main factors of variation. Milk yield is generally reached between 2 and 3.5 kg per 100 kg liveweight in nursing mares. Peak of lactation is generally comprised between 1 and 3 months of lactation, and lactation persistency is high. Generally, milk yield of dairy mares is lower, with an earlier peak and a lower persistency of lactation than nursing mares. However, experimental data are sometimes questionable, because a reliable measurement of milk yield is difficult, due to the high frequency of sucklings by foal. In dairy mares, milk yield depends on frequency and conditions of milking, because of the small capacity of the udder. Differences in milk yield of nursing mares depends to a large extent on their liveweight. For dairy mares, between-breed differences are important for a same liveweight. Influence of diet on liveweight is limited. A moderate effect of energy level is observed. Few data are available on the effect of diet composition, which appears moderate too. Thin mares at foaling may produce less milk than mares in good condition. Further research is necessary to improve the knowledge of factors of variation of milk yield.