RESPONSE OF DAIRY-COWS TO BARLEY-GRAIN, TALLOW OR WHOLE SUNFLOWER SEED AS SUPPLEMENTAL ENERGY IN EARLY LACTATION

Diets containing barley grain (Bar) or supplemental lipid as tallow (T al) or whole sunflower seed (Sun) as sources of supplemental energy in early lactation were fed to 12 primiparous (PP) and 18 multiparous (M P) cows for 12 wk starting 14 d postpartum. Diets had similar estimate d net energy (lactation) content. MP cows had 9.7 and 7.9% higher milk yield with Tal and Sun, respectively, than with Bar, with no apparent difference in mean intake of dry matter (DM). The cows fed the Tal an d Sun diets had lower (P < 0.05) DM intakes at weeks 10, 11 and 12 com pared with DM intake at week 1 than the cows fed the Bar diet. The mil k yield of PP cows was 13 % lower with the Tal diet than the other two diets during weeks 1-7, with no difference between Bar and Sun during the experiment. Fat yield was 36 % lower with Tal-fed PP cows than wi th Sun-fed PP cows and 27 % higher with Tal-fed MP cows than with Sun- fed MP cows. Weight gain, as opposed to fat production, was favored wi th Tal-fed PP cows, while weight gain and fat production were equally favored with Sun-fed PP cows. A high acetate to propionate ratio, the result of a higher acid detergent fiber content obtained by replacing barley grain with lipid plus roughage, was responsible for the lactati onal response of MP cows to supplemental lipid.