Two commercially available progestogen products for cattle, melengestrol acetate (MGA) and norgestomet (SMB) , were evaluated for their ability to induce synchronized estrus in anovulatory ewes. Seasonally anestrous ewes (n=232; determined by blood serum progesterone concentration) of mixed breeding were randomly assigned within broad age groups to one of seven treatments: 1) control (C); 2) MGA only (OMGA); 3) MGA + zeranol (RMGA); 4) MGA + PG-600 (PMGA; 400 IU pregnant mare's serum gonadotropin + 200 IU human chorionic gonadotropin in a 5 mL dose); 5) 5MB only (OSMB); 6) 5MB + zeranol (RSMB); and 7) 5MB + PG-600 (PSMB). Beginning 10 d before breeding, OMGA, RMGA, and PMGA ewes were fed .3 mg MGA/d provided through a mixture of shelled com and a commercially prepared pelleted supplement containing MGA. Concomitantly, OSMB, RSMB, and PSMB ewes were given a 3 mg norgestomet implant inserted subcutaneously on the back of the ear. Immediately preceding initiation of the MGA and 5MB treatments, RMGA and RSMB ewes were given a single i.m. injection of 2.5 mg zeranol. At the end of the 10-d treatment period, MGA feeding was discontinued and the norgestomet implants were removed. Concomitantly, PMGA and PSMB ewes were given a single i.m. injection of PG-600 (5 mL). All treatment groups were combined into one breeding group on May 4, 1992, with a ram to ewe ratio of 1: 17 for a 30-d breeding period. Mating to synchronized estrus was greater (P < .0001) for progestogentreated ewes. Within progestogen treatments, more (P < .000 1) 5MB ewes were marked within the first 5 d of breeding than MGA ewes. Overall, there were no treatment differences in estrus response for the 30-d breeding period. Blood serum samples collected during the first 14 d of breeding were analyzed for progesterone as an indicator of corpora lutea formation. Even though a large proportion of C ewes displayed luteal activity, only 12 % exhibited behavioral estrus within the first 17 d of breeding. Progestogen treated ewes exhibited a shorter mean interval (P < .0001) from ram introduction to lambing. Fertility and prolificacy were not different for C, MGA, or 5MB ewes. Of the two progestogen treatments used alone, lambing rate was 85 and 59 % (P < .03) for OMGA and OSMB ewes, respectively. Ewes plimed with zeranol before MGA or 5MB treatment exhibited similar levels of fertility and intervals from ram introduction to lambing compared with ewes receiving an injection of PG-600 after progestogen treatment. These data indicate that progestogen products commercially available for cattle may be useful in enhancing out-of-season breeding performance in sheep. / Master of Science

Thirty-one Dorset (D), 24 Finnish Landrace (F), 35 Barbados Blackbelly x Dorset (BD), 10 Dorset x Finn (F), 24 Finn x Dorset (FD) and 35 grade Rambouillet (R) ewes were exposed to rams in various seasons. Ewes were born in 1979 or 1980; no R ewes were born in 1980. Ewes were bred in April, 1980 (APR80); November, 1980 (NOV80); August, 1981 (AUG81); May, 1982 (MAY82); and April, 1983 (APR83). Ewes born in 1980 entered the study in NOV80. The analytical model used to describe ewe performance included effects of ewe birth year (EBY), breed/EBY, season/EBY, breed x season/EBY and ewe (random). / Master of Science

The aim of this thesis was to evaluate the influence of the addition of linseed oil to pregnant and lactating ewes to rearing of lambs. For more conclusive results ewes were divided into groups that received linseed oil (for testing) and the group without the constituents of linseed oil in the diet (control). Effect of linseed oil was demonstrated in ewes blood analysis. Analysis of blood parameters were monitored three - cholesterol, triglycerides and lipase. Physiological levels of cholesterol in sheep is 1,7 mmol.l-1. Before the test was observed in ewes cholesterol levels from 1,6 to 2,2 mmol.l-1 and after the test in the range from 1,3 to 1-9 mmol.l-1. Cholesterol after the test decreased in both the test and the control group. Natural levels of triglycerides in ewes is 0.8 mmol.l-1. In our case, the TAG content was below this threshold. Before the test from 0,18 to 0,22 mmol.l-1 after the test from 0.08 to 0.19 mmol.l-1. In test and control groups after the test content triglycerides decreased. After the test, reducing the content of the lipase in the test group and an increase of the content of the control group. Lambs of control and test group ewes were compared on the following criteria: average daily gain (higher increases should control group lambs), weight in control days, the chemical composition of meat - nitrogen, protein and fats. The normal composition of lamb meat: 21 % crude protein, 4,75 % fat and 1,1 % ash. In our case, the content of the NL test group 22,3 % and 21,8 % of the control group, the fat content of the test group and the control 6,5 % and 5,4 %, ash content in the test group and the control 1,23 % and 1,25 %. Further monitoring criteria: weight in carcass weight (between groups) and analysis of blood (cholesterol, triglycerides and lipase) - no difference between test and control lambs.