Effect on Fertil Ity of Freezing Large Numbers of Straws of Bovine Spermatozoa in a Mechanical Freezer 1
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چکیده
Ferti l i ty of semen frozen in a mechanica~ forced-vapor freezer was compared with that frozen in static nitrogen (N) vapor. Semen from 10 Holstein bulls was extended in milk-10% glycerol at 30 x 106 progressively motile spermatozoa/ml and packaged in .5-ml French straws. Straws were divided into three equal g roups ' bu l l l ' co l l ec t ion day -I and frozen in a mechanical freezer at full or half loads (7,250 • 250 or 3,500 + 250 straws in 5-straw goblets on metal canes) or in static N vapor (330 + 30 straws held singly on horizontal racks). For field distribution, straws frozen in static N vapor also were placed in 5-straw goblets on canes after being frozen. Each of the two goblets on a cane held a different treatment. Based on 75-d nonreturn rates for 23,137 first service inseminations, ferti l i ty was 1.6 percentage points higher (P<.05) for semen frozen in static vapor (66.3%) than that frozen in a fully loaded mechanical freezer (64.7%). The difference of 1.3 percentage points in ferti l i ty favoring static vapor over freezing a half load in a mechanical freezer (65.0%) approached significance (P = .06); half and full loads did not vary (P>.05). In conclusion, the small increase in ferti l i ty favoring static over forcedvapor freezing supports use of the static vapor method unless the savings in time and labor of
منابع مشابه
Effect of freezing large numbers of straws of bovine spermatozoa in an automatic freezer on post-thaw motility and acrosomal retention.
Nine ejaculates were extended, placed in .5ml French straws and frozen vertically in two automatic forced vapor freezers (Linde BF-4 and FC-3) at three loads (2,500, 5,000 and full capacity of 7,500 straws in 5-straw goblets on canes). For each load, six locations within each freezing chamber were compared: upper and lower levels of the center, intermediate and corner areas. Semen was extended ...
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