Factors contributing to milk yield variation among cows in a cow–calf contact system in early lactation

The conventional dairy production system involves separation of the cow and calf at around 24 h after birth. Due to public concerns regarding this early separation, a few farmers are taking up the cow–calf contact system. However, some farmers have cited great variation in milk yield delivered to the parlor by cows in this sytem, with this being detrimental because it leads to low farm returns. The main objective of this study was to determine the source of variation in milk delivered to the parlor among cows in a cow–calf contact system. The study examined milk yield records for the first 28 d of lactation for 110 fall- and spring-calving cows from a farm running a full-time cow–calf contact system to investigate factors leading to variation among cows in milk delivered to the parlor. We observed great individual variation in milk yield delivered to the parlor among cows, with the range between the highest and lowest average being 22 L/d. The sex of the calf had an effect on the average milk yield delivered to the parlor: cows with female calves had higher average milk yield (Wald = 5.61, df = 1). Additionally, the lactation number of the dam affected average milk yield delivered to the parlor, with cows in their third lactation and above having the highest milk yield average (Wald = 20.90, df = 2). From the results of this study, we conclude that sex of the calf and lactation number of the dam affect milk yield delivered to the milking parlor in a cow–calf contact system.