Methods of Collection and Lipid Composition of Teat Canal Keratin In Dry and Lactating Cows

Abstract

Methods for collecting keratin from the teat canal were examined to select a procedure to obtain representative samples for lipid analysis. Data obtained by solvent extraction of excised teats were compared with those obtained by scraping keratin from dissected teats of lactating and dry cows. Solvent extraction with petroleum ether or 2:1 chloroform-methanol yielded similar dry weights of material. However, both solvents removed large amounts of material other than keratin from the teat canal. The lipid class and fatty acid profiles of the material extracted by solvent flushing were not similar to profiles obtained by scraping keratin from the teat canal. A metal tapestry needle was suitable for collection of keratin from the teat canal of living cows. About 78% of the keratin present in the teat was collected with the needle. Lipid composition of keratin collected with the needle was the same as in keratin scraped from excised teats. The tapestry needle was suitable as a tool for collecting repeatable, representative samples of keratin for analysis from single teat canals of living cows.

How teat canal keratin depends on the length and diameter of the teat canal in dairy cows

“…First, the amount of keratin recovered by this method may not represent the true amount of keratin actually present in the teat canal. That would contradict Bright et al (1990) who stated that 70 . 3±3 .…”

“…4 % of the keratin in lactating cows was removed by reaming the teat with a tapestry needle. However, Bright et al (1990) based their conclusions on a very limited number of samples. Bright et al (1990) reamed the left teats of eight lactating cows (16 teats) and thereafter excised teats and scraped keratin from teat canals to determine the percentage of total keratin removed by reaming.…”

“…If CMT score was above 3, the keratin sample was excluded. Keratin sampling was performed with a size 14 tapestry needle, as described by Bright et al (1990). Before teat preparation, teat ends were gently scrubbed with ethanol.…”

“…To study the biology of the keratin lining, e.g., its turnover, and its relation to mastitis defence, reliable methods of collecting keratin in vivo for quantitative and qualitative analysis are necessary. Bright et al (1990) compared methods for keratin collection in vivo and suggested that a tapestry needle was a suitable tool for collecting repeatable, representative samples of keratin for lipid analysis from single teat canals of living cows.…”

“…TCL and proximal, medial and distal TCD were measured and the amount of keratin present in the teat canal was determined. The objective of the present study was to investigate whether TCL and TCD influence the dry weight of keratin removed in vivo by a tapestry needle using the procedure suggested by Bright et al (1990).…”