Lower Milk Fat Percentage Research Articles

Milk composition and feed intake in dairy cows selected for high or low milk fat percentage

Dairy cows, selected for high (HFI) or low (LFI) milk fat percentage but equal fat-corrected milk (FCM) yield, were studied regarding feed intake, milk production, milk composition, body weight and body condition. Forty-eight Swedish Red and White breed primiparous and multiparous cows from the selection lines, fed the same diet and milked twice a day, were followed during one lactation. The selection lines produced on average the same total amount of FCM, milk fat and protein. The LFI cows yielded greater milk volume and more total amount of lactose, but the HFI cows had higher percentages of milk fat, total protein and casein. Milk fat from the LFI cows had a smaller proportion of palmitic acid and larger proportions of linoleic and linolenic acids, compared with the HFI cows. No differences in body weight were found, but the LFI cows had more subcutaneous fat over the longissimus dorsi muscle, and tended to have a higher feed intake than the HFI cows. The study indicates that the selection lines differ in metabolism and partitioning of nutrients.

Response in Two Commercial Holstein Herds to Addition of Sodium Bicarbonate to Alfalfa Hay-Based Diets

Feeding trials were conducted in two commercial dairy herds to evaluate the addition of .8% sodium bicarbonate to alfalfa hay-based diets. Approximately half of each herd served as controls and the other half was fed the same diet with sodium bicarbonate. A total of 1280 Dairy Herd Improvement Association lactation records were obtained in the two herds during the trials. Cows in herd 1 were milked three times daily and cows in herd 2 were milked twice daily.In herd 1, milk production from control and bicarbonate groups was: first lactation cows, 7491 and 7748 kg/cow; second lactation cows, 8363 and 8791 kg/cow; and third and higher lactation cows, 8713 and 9562 kg/cow. There were no differences in milkfat or solids-not-fat percentages between treatment groups.In herd 2, milk production from control and bicarbonate groups was: first lactation cows, 6800 and 7158 kg/cow; second lactation cows, 8487 and 8082 kg/cow; and third and higher lactation cows, 8807 and 8216 kg/cow. First lactation cows fed sodium bicarbonate had a lower milk fat percentage than controls. There were no other differences in milk fat or solids-not-fat percentages between treatment groups.

Relative Economic Importance of Milk and Milk Fat Percentage in Selecting Artificially Inseminated Proven Dairy Sires

The relative economic importance of the genetic changes in milk yield and milk fat percentage attributed to individual sires was investigated for artificially inseminated (AI) proven sires of the five major dairy breeds in the United States, summarized with daughter-herdmate comparisons in 1965. Twenty groups of sires were studied with multiple regression techniques which took into consideration representative pricing systems, breed averages, and sire effects for milk yield and milk fat percentage expressed as differences from herdmates for their AI daughters. For the entire population of sires and a representative pricing system, variations in milk fat percentage were 30, 32, 43, 47, and 37% as important as were variations in milk yield for Ayrshires, Brown Swiss, Guernseys, Holsteins, and Jerseys, respectively. Within the top third of the sires on milk production only, variations in milk fat percentage were 54, 55, 89, 82, and 58% as important as were variations in milk yield for Ayrshires, Brown Swiss, Guernseys, Holsteins, and Jerseys, respectively. Sires of the Guernsey, Jersey, and Holstein breeds, summarized for the first time in 1965, were similar to the entire population of sires in the relative importance of milk yield and milk fat percentage. Interrelated factors which tended to make variations in milk fat percentage have a relatively high economic importance were 1) a high level of production, 2) low milk fat percentage, 3) low blend price paid for the milk, 4) high milk fat differential, and 5) basing the blend price on a high milk fat percentage.