Relationship of Age at First Calving, Days Open, Days Dry, and Herdlife to a Profit function for Dairy Cattle
Relationship of Age at First Calving, Days Open, Days Dry, and Herdlife to a Profit function for Dairy Cattle
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奶牛首次产犊日龄、开放天数、干奶天数和畜群寿命与利润函数的关系
DOI：
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
F. Allaire
中科院分区：
文献类型：
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作者：
G. S. Gill;F. Allaire
本文通过对933头荷斯坦奶牛的一生记录，研究了奶牛育种和管理因素与经济效益的关系。从产奶量、体重、繁殖性能、平均寿命、饲料能量价格、牛奶价格、犊牛价格、残值和固定成本定义利润函数。个体奶牛的统计数据包括产奶量、每次泌乳的产奶天数、脂肪百分比、首次产犊和成熟时的体重、人工授精次数、每次产犊和处置时的年龄。每个特征的值最大化第二特征被定义为最优的。最佳的开放天数和干燥天数分别为31.0和10.5。略大的百分比是最佳的总性能性状，利润的生活，牛奶的生活，和寿命。第一次产犊的最佳年龄为22.5至23.5个月。在25个月的年龄期间产犊的奶牛，每天产犊的利润比那些产犊早的奶牛大0.05美元。开产天数、干产天数和首次产犊日龄分别占产犊日龄变异的10.0%、4.5%和0.9%;占产奶日龄变异的4.3%、18.8%和0.6%;占产奶日龄利润变异的8.1%、8.3%和5.2%。第一胎产犊年龄与开产天数百分比和产犊寿命之间的相关性为0.05和-0.10。对于第一次产犊时25月龄、124天开产和42天干产的奶牛，预期每天产奶期的最大利润，同时每天产奶期和产奶期的产奶量最大。
Abstract Relationships of breeding and management factors to economic return for dairy cows were studied in lifetime records from 933 Holstein cows. A profit function was defined from milk production, body weight, reproductive performance, herdlife, and prices for feed energy, milk, calves, salvage value, and fixed costs. Statistics on individual cows were milk yield, days in milk for each lactation, fat percent, weight at first calving and maturity, number artificial inseminations, and age at each calving and at disposal. Values of each trait maximizing a second trait are defined as optimal. Optimum percent days open and days dry were 31.0 and 10.5 for profit per day-herdlife. Slightly larger percentages were optimal for total performance traits, profit-life, milk-life, and herdlife. Optimum age at first calving for total lifetime performance was 22.5 to 23.5 mo. Profit per day of herdlife was $.05 larger for cows calving during the 25th mo of age than those calving earlier. Days open, days dry, and age at first calving accounted for 10.0, 4.5, and .9% of variation in herdlife; for 4.3, 18.8, and .6% in milk per day-life; and 8.1, 8.3, and 5.2% of variation in profit per day-herdlife. Correlations between age at first calving with percent days open and herdlife were .05 and −.10. Maximum profit per day-herdlife was expected for cows with 25 mo of age at first calving, 124 days open, and 42 days dry while maximizing milk per day-life and herdlife.