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改变饲喂方式对奶牛乳脂率含量的影响 总被引:1,自引:0,他引:1
近年来,尽管奶牛的个体产奶量有所提高,但伴随着一个普遍性的问题是乳脂率很难提高,而且有下降的趋势。影响乳脂率高低的因素除遗传 (品种、个体 )外,还与外界因素 (饲料、饲养管理、生理阶段、气候等 )有关。由于奶业发展过程中尚未形成统一的“按质论价”的收购标准,故在一些奶牛场 (家 )只注重产奶量的提高而忽视了奶质量。由于奶质量达不到购方的要求而给生产单位造成经济损失 (如灵武奶牛场在 1999年 8月份因鲜奶乳脂率达不到夏进乳品公司的收购标准而损失 7万多元 )。同时,从营养角度出发,奶牛日粮中干物质采食量不足,尤其是… 相似文献
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五、日粮脂肪含量 对奶成分影响最大的是由日粮脂肪和碳水化合物的结构引起,在正常范围内日粮的蛋白质不起作用。等能日粮增加脂肪可提高乳脂率。日粮的脂肪酸向乳脂的转化依赖于脂肪酸在日粮的含量,泌乳阶段和糖元营养的摄入影响乳脂率和脂肪组织的代谢平衡。 相似文献
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近年来,我国奶牛个体产奶量不断提高,但乳脂率下降的问题引起人们的普遍关注。乳脂率的高低直接影响乳产品的质量。现有奶牛的乳脂率难以达到3.5%的育种指标,长期在2.8%~3.5%之间徘徊。 相似文献
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正热应激对奶牛的采食量、反刍功能、营养消化与吸收都有严重的负面影响。由于生物学和环境之间某些较为复杂的相互作用,降低了乳产量和乳成分的含量。热应激情况下,由于饲料采食量的减少,纤维消化率的降低,以及瘤胃反式脂肪酸的产生,故乳脂率通常是降低的。不过由于热应激期间体脂的动用,乳脂率也偶有升高的现象。饲料采食量的减少使得氨基酸摄入量降低,加之热应激期间微生物数 相似文献
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近年来,我国奶牛业个体产奶量在不断提高,但同时乳脂率的下降引起人们的普遍关注,乳脂率的高低直接影响乳产品的质量,现有奶牛的乳脂率难以达到育种指标3.5%,长期在2.8%-3.5%之间徘徊。造成乳脂率低的原因主要有以下几个方面:其一,各地在选种选配时,只注重产奶量的选择,忽视乳脂率及乳蛋白的选择,注重产奶数量,忽视奶的质量,结果造成牛奶稀薄乏味、浓香味消失,干物质减少。其二,全国各地鲜奶收购没有实行统一的“按质论价,优质优价”原则,各乳品厂(尤其是小型个体乳品厂)牛奶质量(乳脂率、乳蛋白和干物质)检测手段落后,很多乳品厂仍然以奶量… 相似文献
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改善牛奶乳脂率的几项关键措施 总被引:1,自引:0,他引:1
牛奶富有营养价值 ,其成分可分为水和固形物两部分 ,固形物包括乳蛋白、乳脂肪、乳糖、矿物质、维生素等多种物质。固形物含量多少影响乳的品质 ,乳脂率是衡量乳质优劣的重要指标 ,含量一般为 3 %~ 5 %。乳脂中含有人体必需的亚麻酸和花生油酸及多种脂溶性维生素、磷脂类等。提高乳脂率的主要方法是进行奶牛品种改良 ,选择优质饲料 ,饲养管理也是提高乳脂率的重要因素之一。1 选育好的品种和个体不同品种牛的产乳量和乳脂率有很大差异。经过精心选育的品种如荷斯坦牛 ,其产乳量显著高于地方品种。产乳量和乳脂率之间存在负相关 ,产乳量较… 相似文献
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半胱胺对奶牛产奶量、乳脂率和饲料转化率的影响 总被引:10,自引:0,他引:10
半胱胺又名 β -巯基乙胺 (Cysteamine ,Cs) ,是动物体内辅酶A(CoA)的组成部分 ,为一种非激素类生理活性物质 ,在动物体细胞中可检测到其存在 (Millard ,1 985 )。经多种动物试验研究表明 ,饲料中添加半胱胺能耗竭动物体内的生长抑制激素(SS) ,同时促进机体内源性生长激素 (GH)的合成释放增加 ,随着生长抑制激素浓度的降低 ,消化液分泌增多 ,促进了消化和吸收 ,整体代谢水平提高(王燕玲等 ,1 999)。为探讨饲料中添加半胱胺对奶牛产奶量的影响 ,进行本次试验。1 材料与方法1 1 试验药品 半胱胺 (Cs87)由上海华广达生化实业有限公司… 相似文献
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Keiji OKADA Junro KATO Tamako MIYAZAKI Shigeru SATO Jun YASUDA 《Animal Science Journal》2010,81(1):85-88
In order to understand the effects of the automatic milk replacer feeding system on calf health, we examined the effect of frequent milk feeding on curd formation in the abomasum using ultrasonographic imaging. Eight male Holstein calves were divided into a milk-replacer group and a fresh milk group. Calves were fed twice a day to 12 days after birth (Period A). From 13 days, calves were fed six times a day (Period B). The abomasal fluid was taken by paracentesis. In both periods A and B, the fresh milk group formed bigger curds faster than the milk replacer group. The curd score of the milk replacer group in period B at 2 h was significant lower than those of both groups in period A. The pH in the abomasum was lower in period B than in period A. We could not identify the location of the abomasum in the milk replacer group during period B at almost time points. Our experiment suggests the possibility that frequent feeding of milk replacer causes incomplete hydrolysis of κ-casein as well as curd formation, thus reducing the digestibility compared to the feeding of the milk replacer twice per day or frequent feeding of fresh milk. 相似文献
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This study was conducted to determine the effect of feeding high milk volumes on the growth rate, health and cross-sucking behaviour in group-fed Jersey calves. Three-day-old heifers (n = 120) in a seasonal calving dairy herd were randomly assigned to one of 6 treatment groups. Three groups received high milk volumes (HMV), consisting of ad libitum milk or milk replacer feeding twice a day, while 3 groups received restricted milk volumes (RMV), consisting of 2 l twice daily, during the pre-weaning period. After a pre-weaning period during which feeding was reduced to once daily, all calves were weaned at 42 days and monitored until 60 days of age. Adjusting for birth mass, birth date, dam parity and sire, average daily mass gain (ADG), both pre-weaning (days 0-42) and overall (days 0-60), was higher in HMV than in RMV calves (P < 0.001). After weaning, growth rates showed no differences and at 60 days of age the HMV calves maintained a 6.74 kg advantage in mean body mass (P < 0.001). The mean intake of dry starter feed was higher in RMV than in HMV calves. Overall feed conversion rate of HMV calves was 9.6 % better than RMV calves. However, the variable cost per kg mass gain was 12 % higher for HMV calves. In the RMV groups 75 % of calves showed cross-sucking behaviour pre-weaning and 18 % post-weaning, whereas in HMV calves the proportions were 2 % and 7 %, respectively. There was no significant effect of milk volume on the incidence of diarrhoea. We conclude that the feeding of high volumes of milk to Jersey calves has a positive effect on growth rate, without compromising health or reducing solid feed intake after weaning. However, the higher cost of such a feeding system may limit its implementation. 相似文献
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