北达科他州的秋季产犊

秋季产犊对生产商来说可能有几个好处，包括:

1. Ideal calving weather: fall calving offers ideal conditions with no worries of winter storms. 生产商报告几乎没有冲刷问题.
2. 经济和管理的灵活性:在秋季产犊, 小牛准备在一年中非传统的时间出售. 由于这些时候牛的供应有限，它们可以溢价出售. 小牛可以在5月或6月作为草牛出售，也可以作为一岁的小牛放牧出售. Cows are also at a premium in the spring when the fall calves are weaned and when cull cows are sold.
3. 牛的需求:牛的成本大大降低运行一个春季和秋季的牛群. 同一头公牛可以用于两个畜群.
4. 放养率灵活性:在干旱年份，小牛可以在断奶时出售. 当饲料充足时，它们可以作为牲畜放牧.
5. Multiple use of facilities: fall calves can utilize well protected areas during winter and be moved out before spring calving begins.
6. 劳动:秋季产犊可能有助于分散每年的工作量.
7. 现金流:因为小牛是在非传统时期出售的, 收入在一个日历年里分布得更均匀.

然而，下降产犊可能有一些缺点. 它们包括:

1. Feed requirements: the fall calving cow may require higher levels of nutrition to keep performance at acceptable levels.
2. 劳动力与收成的冲突:大多数牧场主也从事农业. 秋季产犊可能与收获相冲突，但不会影响春季播种.
3. 设施:在严冬天气下，秋天的小牛确实需要一个保护良好的区域. 在这个地区，防风栅栏和垫料是必需的.
4. 动物生产性能:秋季犊牛的生产性能不确定.

过程

Nineteen young open cows from the CGREC herd and 18 open cows from a local rancher were acquired in the fall of 1992 to start a fall calving herd. 每年秋天都要从春季产犊的牛群中增加更多的奶牛. 通常, the breeding season for the fall calving cows begins about November 1 and continues for about 45 days. This means that the cows begin calving about the second week of August and are done by October 1. 冬食大约从11月1日开始. Cows with calves are fed approximately 28 pounds of alfalfa - grass hay per head 每天 until weaning in mid-March. 从春季畜群中添加的裸牛，以质量较低的草原干草过冬. 这些牛, 一次繁殖, have low requirements because they are not lactating and are in their first trimester of pregnancy. 小牛在3月中旬到4月中旬断奶. 然后，它们被放在背景中，直到5月份出现在原生草地上. 9月1日前它们都在放牧. 从4月下旬开始，奶牛就被放上温顺的草地. 然后在6月将它们转移到原生牧场.

结果与讨论

表1 展示了秋季产犊奶牛的表现. We started with 37 cows in 1992 and have followed this same group of cows through four calf crops to date. 当我们开始这个项目时，奶牛的平均体重为1176磅. 第一个冬天，我们用低质量的CRP干草和稻草让这些奶牛过冬, 因为它们还没有哺乳期. We wanted the cows to maintain their weight the first winter and they weighed 1185 at spring turnout. 81%的奶牛怀孕了. The cows gained a tremendous amount of weight and condition during the summer and weighed 1417 pounds on December 10, 1993. 这是在奶牛产犊后大约90天. The extra weight allows us to restrict their diet somewhat and utilize some of their excess condition. 表1 also shows how the fall calving cows have been able to maintain their weight over the years. 这些奶牛的怀孕率变化不定，最高可达96头.6%，最低为81.1%. We may need to improve the nutrition of these fall calving cows prior to and during the breeding season to improve the rebreeding of these cows.

表2 比较调整后的205天断奶体重我们秋天出生的小牛. 只有来自相似品种的小牛被用于这项比较. 1994年，春天出生的小牛重了23磅(577磅). Vs 600磅.)比秋天出生的小牛要多. The year 1995 also showed an adjusted weaning weight advantage for the spring born calves of 26 pounds (550 lbs. Vs 576磅.). 1996 showed an advantage of 43 pounds and 1997 showed a 38 pound weaning weight advantage. The fall born calves had a four-year average weaning weight of 566 pounds and the spring born calves averaged 599 pounds. 这四年的平均水平, the spring born calves had adjusted weaning weights 33 pounds heavier than our fall born calves.

表3 显示了秋季出生的小牛在夏季储存阶段的表现. 头两年, 1994年和1995年, 1996年和1997年的数据还包括小母牛，而只有阉牛被放牧. 春季出栏时，小牛的平均体重为581磅, 1995年最高为631英镑，1997年最低为544英镑. 1997年较低的体重肯定是由于漫长而严酷的冬季造成的.

这些小牛在9月5日左右离开草地，平均体重为791磅. They have averaged 116 days on grass over the four-year period with an average daily gain of 1.81磅. No supplemental feed other than salt and mineral were provided during this summer period.

在1995年，我们决定评估我们的秋天出生的牛在饲料场和铁路. 我们将这些阉牛与一组春天出生的类似育种的阉牛进行了比较. The spring born steers were finished in Kansas while the fall born steers were finished in Fargo. 表4 显示反馈信息. 春天出生的牛有更轻的开始重量(614磅). Vs 775磅.)，但最终重量更重(1299磅). Vs 1219磅.). 春天出生的阉牛比秋天出生的多吃饲料99天(223天对124天). 秋天出生的小牛长得更快.57 vs 3.08 ADG)，但两组的胴体分级选择比例相似(55.6% to 57.0%). 因为春天出生的小牛吃饲料的时间更长，饲料成本更高, 以及更低的销售价格, 他们损失了105美元.人均96元. 秋天出生的公牛回报了44美元的利润.每人11美元. 1996 was probably not typical of most years with a skyrocketing of the corn market and a plunge in the fed cattle market. 未来我们可能会跟踪更多的小象群.

许多生产者对秋季产犊奶牛饲料成本的增加表示担忧. 我们记录了秋季产犊奶牛的平均采食量. Both spring and fall calving cows are fed long stem grass or alfalfa-grass hay from large round bales. 捆包定期称重, 但最终的消耗量只是估计值，其中还包括腐败和浪费. 表5 为1995年春、秋季产犊牛的饲料消耗量. The cows are fed similar diets, but for different lengths of time and at different times of the year. 我们将其分为妊娠期饮食和妊娠后期-哺乳期饮食. The gestation diet is generally lower quality and includes CRP hay, prairie hay and sometimes straw. The spring calving cows are fed this diet for about 90 days starting on about December 1. The fall calving cows are fed the gestation diet for about 30 days after weaning their calves in early April. 我们对这些干草的估价是每吨35美元. The late gestation-lactation diet is fed to the spring calving cows starting about 30 days prior to calving until turnout to pasture. A similar diet is fed to the fall calving cows starting at breeding time in early November until weaning in late March. 这种日粮由较优质的干草组成，包括苜蓿草干草和燕麦干草. The feed cost for the fall calving cows is estimated at about $20 higher than the spring calving cows ($144.00 vs $124.20). 两组在6磅时消耗的总干草磅数非常相似,春犊120磅，6磅,600磅给秋天的小牛. 秋季产犊对地区生产者来说是一个可行的选择. The project is being continued to increase the database on all aspects of fall calving in the Coteau area of North Dakota.

1998年3月