DePeters E J, Taylor S J, Franke A A, Aguirre A
J Dairy Sci. 1985 Apr;68(4):897-902. doi: 10.3168/jds.S0022-0302(85)80907-3.
Complete mixed diets containing 0, 10, 15, or 20% whole cottonseed were fed to 12 cows in a 4 X 4 Latin square design. Cows were assigned to the Latin square by production status resulting in one square each for cows in early first lactation and older cows either in early or late lactation. Diets were fed for ad libitum intake, and periods were 21 days. Percentages of milk fat and total solids increased, and protein percentage decreased with cottonseed feeding. Milk casein nitrogen decreased from .387 to .375% with cottonseed feeding. Nitrogen in whey remained unchanged, and nonprotein nitrogen increased. Proportion of total nitrogen in casein and whey fractions was not altered, but proportion of nonprotein nitrogen increased. Cottonseed decreased proportions of short-chain fatty acids (carbon-6 to carbon-16) in milk and increased stearic and oleic acids. Actual yield of milk was not affected by cottonseed feeding, but yields of fat-corrected milk and milk fat were increased. Production status affected milk composition with older cows in early lactation producing milk of lower fat, total solids, and protein content compared with cows in other groups. Casein nitrogen was highest for first-lactation and lowest for older, high-producing cows. Whey nitrogen was highest for older, low-producing cows. First-lactation cows had the highest proportion of nitrogen in the casein fraction, and older, low-producing cows had the lowest. Milk fatty acid composition changed little with status.
采用4×4拉丁方设计，给12头奶牛饲喂含有0%、10%、15%或20%全棉籽的全混合日粮。根据生产状况将奶牛分配到拉丁方中，初产早期的奶牛和处于泌乳早期或晚期的老龄奶牛各占一个方格。日粮按随意采食量投喂，每期为21天。随着棉籽饲喂量增加，乳脂率和总固形物百分比升高，蛋白质百分比降低。饲喂棉籽后，乳中酪蛋白氮从0.387%降至0.375%。乳清中的氮含量保持不变，非蛋白氮增加。酪蛋白和乳清组分中总氮的比例未改变，但非蛋白氮的比例增加。棉籽降低了乳中短链脂肪酸（碳6至碳16）的比例，增加了硬脂酸和油酸的比例。棉籽饲喂对实际产奶量没有影响，但校正乳和乳脂产量增加。生产状况影响乳成分，与其他组的奶牛相比，初产早期的老龄奶牛产奶的脂肪、总固形物和蛋白质含量较低。酪蛋白氮在头胎奶牛中最高，在老龄高产奶牛中最低。乳清氮在老龄低产奶牛中最高。头胎奶牛酪蛋白组分中的氮比例最高，老龄低产奶牛最低。乳脂肪酸组成随生产状况变化不大。
