Grass samples were harvested during the 1993 growing season after a precut on April 27, 1993 and were stored frozen or left to ensile in 30-L buckets. Effects on chemical composition and fermentation kinetics of the maturation of the grass and of ensiling were investigated. Chemical composition and fermentation kinetics were determined using the gas production technique, in vitro techniques, and the nylon bag technique. Two silage samples were also investigated in vivo. Maturation caused a decrease in crude protein content and organic matter degradability and an increase in neutral detergent fiber, acid detergent fiber, and lignin contents. Degradation rates were highest for the youngest samples and decreased as grass and silage matured. This result could be observed from the first derivative of the cumulative gas production curves (i.e., the rate of gas production) and from the gas production parameters. The rate of degradation of the nonsoluble fraction of the young samples, determined using the gas production technique, was relatively higher in rumen fluid from a cow fed silage from grass cut at a young stage. More mature samples were degraded relatively faster in rumen fluid from a cow fed mature grass silage, suggesting a specific adaptation of the rumen microorganisms to the grass properties. There was a good relationship among the second phase of gas production (i.e., fermentation of the nonsoluble fraction), maturity of the grass and grass silage samples, degradability determined with the Tilley and Terry technique, and degradability determined after 46 h of incubation in rumen fluid. Results obtained with both of the different in vitro techniques and the nylon bag technique were confirmed by the in vivo experiments involving the two silage samples.

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Forty pregnant ewes of more than two successive lambing seasons, at the second half of gestation period, were used to evaluate the effects of supplemented vitamin A on growth performance, blood constituents, levels of vitamin A and β carotene of Saidi ewes and their offspring. Pregnant ewes (48.48 ± 0.09 kg B. W.) were assigned to 4 treatment groups of 10 ewes each in the Farm of Animal Production Department, the Faculty of Agriculture, Assiut University, Assiut, Egypt.. Vitamin A was drenched in the form of pale yellow to brown granular powder as vitamin A acetate content ≥ 1,000,000 IU/g which had been certified by china council for the promotion of international trade. In group I both ewes and lambs were not treated. In group II ewes were not treated while lambs were given 10,000 I.U. In group III ewes were given 150,000 I.U. of vitamin A /head fortnightly while lambs were not treated. In group IV ewes were given 150,000 I.U. of vitamin A /head while lambs were given 10,000 I.U fortnightly. Feeds were offered once daily and fresh tap water was free available allover the day. Ewes were housed in semi open pens under the normal environmental conditions. Before feeding and drinking, ewes were weighed fortnightly throughout the experimental period. Lambs were weighed at birth and then weighed fortnightly throughout the experiment. Blood was obtained every 14 days to evaluate blood constituents in blood serum of ewes and offspring. In general, body weight and daily weight gain in ewes and offspring improved (p>0.05) by supplemented vitamin A. However, blood profiles were not affected by vitamin A supplementation, except mean of platelets volume (MPV) levels were higher (P<0.05) in treated ewes (group IV), while number neutrophils was lower (p<0.05) in untreated lambs (group I) compared with other ones. Concentrations of total protein and globulin were higher (p<0.05) in blood serum of untreated ewes (group I) , while albumin / globulin ratio were higher (p<0.05) in group IV , but levels of albumin reduced (P<0.05) in blood serum of group III compared with other groups. Concentration of total cholesterol increased (p<0.05) in blood serum of group IV compared with other ones. Concentrations of glucose, triglycerides and urea in blood serum were not different (P>0.05) among treatments. Vitamin A and β carotene levels in blood serum of ewes were not different significantly among treatments, while Vitamin A concentration was higher (P<0.05) for lambs in group II and IV of ages 30 and 60 days than other groups. In conclusion, addition vitamin A improved body performance of ewes and their offspring without any harmful effecton blood constituents.

To study the effect of Beta Carotene (BC) treatment on puberty and related phenomena as well as concentrations of vitamin A, and estradiol-17β hormone 48 Farafra ewe lambs were divided into two equal groups. The control group (G1) was injected intramuscularly with 0.1 mg arachis oil, while the treated group (G2) was injected with 0.1 mg BC  arachis oil / kg twice a week from weaning to puberty. Estradiol 17 β, progesterone (P 4 ), BC and vitamin A were assayed in blood sera taken from 6 animals/ group.Results indicated that treatment with BC was accompanied by increasing estradiol-17β and vitamin A concentrations at puberty. Ewe lambs of G2 displayed (P< 0.05) more estrous cases post-puberty than G1. Both groups displayed short cycles at puberty (6.2 d for G2 vs. 7.4 d for G1) with no significant difference between the two groups. P 4 concentration at estrus of puberty was ≥ 1.0 ng/ml of both groups. Post-puberty BC and Vit.A concentrations had (P<0.05) positive correlation in the two studied groups. BC concentration in G2 was higher (P< 0.05) at pre-puberty than post-puberty.In conclusion, BC injection had an impact on number of observed estrous cases, vitamin A and estradiol-17β concentrations at puberty and post-puberty estrus, which might be applied in the animal farms to enhance estrus cases around puberty.