The Langhill Breeding Project: Breeding and Feeding for Total Solids Production in An Experimental Dairy Herd

Extract

To achieve high yields of total solids in a dairy herd requires the implementation of appropriate breeding and feeding strategies. The Edinburgh School of Agriculture's Langhill herd, which consists of 200 cows, embarked on a long-term breeding programme in the early 1970s to demonstrate to what extent genetic improvement might be achieved within a herd, using selection methods available to commercial dairy farmers. The specific selection objective was yield of total solids, with artificial insemination (AI) sires being chosen on their improved contemporary comparison for fat plus protein production and females being selected on their genetic index for the same traits. To measure genetic change, a genetic control population was established. Thus, a section of the herd, currently 25 animals but increasing to 20% of the total herd, are bred from a panel of 50 AI sires selected randomly from the 1976 Milk Marketing Board and Scottish Milk Marketing Board Dairy Bull Progeny Testing Schemes. The herd is given complete diets during the winter housing period, September to May, and grazed on a paddock system in the summer months. The average 305-day yield in the selected herd in 1983 was 6924 kg at 41.8 g fat and 34.2 g protein/kg. This yield shows an increase from the 1977 yield of 5732 kg at 38.7 g fat and 32.5 g protein/kg. Current first-lactation yields average 6107 kg at 42.5 g fat and 33.9 g protein/kg. The food intake of a section of the herd is recorded and initial results suggest that cows producing high yields of solids are more efficient than cows producing lower yields.