ForewordDespite careful pasture management, parasites can become a real threat to profitable sheep production. Thus, even the best grazier must at times resort to some drug to relieve his flock of parasites. Reliance upon such drugs must be even greater at lower levels of management or under adverse conditions which disrupt even the soundest management.Anthelmintic drugs thus have become a necessity for profitable sheep production, particularly in the humid grazing areas. A steady improvement in anthelmintic efficacy has been experienced with the addition of each new drug to the shepherd's shelf. To the long-used copper-sulfate and nicotine sulfate combination was added phenothiazine. Now, one of the most recent additions, thiabendazole, promises to make the sheepman's arsenal against parasites more effective than ever.The work described in this bulletin represents the cooperative efforts of several people. The initial trials conducted in the 1960 grazing season were largely the work of Dr.
The effectiveness of two way selection for serum alkaline phosphatase (S.A.P.) was investigated to determine its influence on productive traits in a White Leghorn population for three generations. The difference between females in the high and low lines at the end of three generations was S3 percent of the S.A.P. level of the foundation population. Selection was based entirely on phenotypic differences. The divergence of the lines was significant and greater in the high line. Computed heritabilities from within sire dam offspring regression for S.A.P. was .42. Heritability estimates from the analysis of variance sire component was .12 ± .09, and from the dam component .76 ± .16. The realized heritability was .45 and .36 for high and low lines respectively.No correlated responses were found during the time of this study for hen day egg production, egg weight, specific gravity or mortality. Hatchability decreased significantly in the high line and fertility decreased significantly in the low line.A build up of phosphatase in the blood occurred during the formation of the egg which would be an indication that the enzyme is involved in egg shell formation.
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