Effects of feeding intensity during the dry period.: 1.: Feed intake, body weight, and milk production
Effects of feeding intensity during the dry period.: 1.: Feed intake, body weight, and milk production
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DOI：
10.3168/jds.s0022-0302(03)73670-4
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发表时间：
2003-03-01
影响因子：
3.5
通讯作者：
Holtenius, K
中科院分区：
文献类型：
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作者：
Agenäs, S;Burstedt, E;Holtenius, K
本试验旨在研究分娩时不同体型奶牛的干物质采食量(DMI)、体况、产奶量和乳成分。24头乳脂含量高或低具有遗传优势的经产奶牛在干燥期被分配到三种日粮中的一种。试验日粮中添加6、9或14.5 kg干物质，提供71、106或177MJ/d的代谢能，分别称为低(L)、中(M)和高(H)干期日粮。这些日粮是在奶牛从前一次哺乳中被晾干时引入的，至少在预期分娩前8周。分娩后，所有奶牛都被随意饲喂另一种完全混合的日粮。饮食治疗在两组之间产生了体重和分娩时身体状况评分的差异。泌乳早期的DMI差异不显著，但在第6~12周，H牛的DMI较低，这与该组奶牛持续的负能量平衡有关。产后4wk，产奶量为38.5+/-0.8千克能量校正牛奶，不同处理或选育系之间没有差异。体重下降主要发生在哺乳期第1~4周，H牛的体重下降幅度最大。H型奶牛在第1~4周乳脂含量较高(C-18：0)，反映了机体组织的动员。处理对乳脂含量和乳蛋白含量没有显著影响，表明如果饲喂优质日粮，哺乳期早期奶牛有可能补偿干奶期营养物质的低摄入量。在DMI wk 6至12处理之间观察到的差异不能用产奶量或身体组织动员的差异来解释。高乳脂遗传优势奶牛乳脂含量为4.7%，低乳脂遗传优势奶牛乳脂含量为4.2%。在整个试验过程中，具有低乳脂含量的遗传优势奶牛有较高体重的趋势。
The objective of this experiment was to study dry matter intake (DMI), body condition, milk yield, and milk composition in cows with different body condition at the time of parturition. Twenty four multiparous cows with genetic merit for high or low milk fat content were assigned to one of three diets during the dry period. The treatments consisted of 6, 9, or 14.5 kg dry matter of a total mixed ration providing 71, 106, or 177 MJ/d of metabolizable energy and are referred to as low (L), medium (M), and high (H) dry period rations, respectively. These diets were introduced when the cows were dried off from the previous lactation, at least 8 wk before expected parturition. After parturition all cows were fed another total mixed ration ad libitum. The dietary treatments generated differences between the groups in body weight as well as in body condition score at parturition. There were no differences in DMI in early lactation, but during wk 6 to 12 DMI was lower among H cows, which was linked to a prolonged negative energy balance in this group. The milk yield was 38.5 +/- 0.8 kg of energy-corrected milk the first 4 wk postpartum and did not differ between treatments or selection lines. Body weight loss mainly occurred in lactation wk 1 to 4 and was greatest in H cows. The mobilization of body tissues was reflected in a higher milk fat content of C-18:0 for the H cows during wk 1 to 4. There were no marked effects of treatments on milk fat content or milk protein con tent, which indicates that cows in early lactation have a potential to compensate for low nutrient intake during the dry period if they are offered a high-quality diet. The observed differences between treatments in DMI wk 6 to 12 could not be explained by differences in milk yield or mobilization of body tissues. Milk fat content was 4.7% in cows with genetic merit for high milk fat content and 4.2% in cows with genetic merit for low milk fat content. There was a tendency for higher body weight in cows with genetic merit for low milk fat content throughout the experiment.