Pirlo G, Miglior F, Speroni M
Animal Production Research Institute, Cremona, Italy.
J Dairy Sci. 2000 Mar;83(3):603-8. doi: 10.3168/jds.S0022-0302(00)74919-8.
The 305-d yield records of 1,048,942 Italian Holstein-Friesian heifers were used to determine the effect of age at first calving on milk yield and fat and protein concentration. Research showed that there is a positive effect of age at first calving on milk yield and fat percentage and a negative effect on protein percentage. In six scenarios of milk price and rearing costs (2 x 3, respectively), the effect of age at first calving on the difference between milk yield returns and rearing costs was calculated. We concluded that the most positive difference was achieved with age at first calving between 23 and 24 mo.
利用1,048,942头意大利荷斯坦-弗里生小母牛的305天产奶量记录，来确定初产年龄对产奶量以及乳脂和蛋白质含量的影响。研究表明，初产年龄对产奶量和乳脂率有积极影响，而对蛋白质率有消极影响。在六种奶价和饲养成本的情景下（分别为2种奶价和3种饲养成本），计算了初产年龄对产奶收益与饲养成本之差的影响。我们得出结论，初产年龄在23至24月龄时，差值最为有利。
