Capuco A V, Wood D L, Quast J W
Gene Evaluation and Mapping Laboratory, USDA-ARS, Beltsville, MD 20705, USA.
J Dairy Res. 2000 Aug;67(3):319-27. doi: 10.1017/s0022029900004295.
The effect of tension of teatcup liners on teat end condition and quantity of keratin in the teat canal was investigated. Liner tension was increased by using longer teatcup shells. The first experiment used six Holstein cows in early lactation. Left quarters were milked with liners under medium or normal tension by using Conewango liners in 142 mm shells. Right quarters were milked with liners under high tension by mounting the liners in teatcup shells 149 mm in length. By day 16 teat end condition and sensitivity to manipulation were worsened by thrice daily milking when liners were under a higher tension. Two subsequent experiments each used 12 different Holstein cows. These cows were in mid lactation and were milked twice daily for 10 or 30 d. Left quarters were milked with liners under high tension Right quarters were milked with liners under low tension by using teatcup shells 126 mm in length. The quantity of keratin removed during milking was not influenced by liner tension: however, the quantity of keratin at the end of the experiments was increased 10-20% in teats that were milked using liners under higher tension. Histological analysis and keratin content were consistent with epithelial hyperplasia induced by milking with liners under increased tension.
研究了奶杯内衬张力对乳头末端状况和乳头管中角蛋白数量的影响。通过使用更长的奶杯外壳来增加内衬张力。第一个实验使用了6头处于泌乳早期的荷斯坦奶牛。左乳区使用142毫米外壳的Conewango内衬，以中等或正常张力挤奶。右乳区通过将内衬安装在149毫米长的奶杯外壳中，以高张力挤奶。到第16天时，当内衬处于较高张力时，每天三次挤奶会使乳头末端状况和对操作的敏感性变差。随后的两个实验各使用了12头不同的荷斯坦奶牛。这些奶牛处于泌乳中期，每天挤奶两次，持续10天或30天。左乳区使用高张力内衬挤奶，右乳区通过使用126毫米长的奶杯外壳，以低张力内衬挤奶。挤奶过程中去除的角蛋白数量不受内衬张力的影响：然而，在实验结束时，使用较高张力内衬挤奶的乳头中角蛋白数量增加了10% - 20%。组织学分析和角蛋白含量与在增加张力下使用内衬挤奶诱导的上皮增生一致。
