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Accueil du site → Doctorat → États-Unis → 1994 → Meeting the nutritional requirements of sheep in semi-arid Morocco

University of Nebraska - Lincoln (1994)

Meeting the nutritional requirements of sheep in semi-arid Morocco

Boulanouar Bouchaib

Titre : Meeting the nutritional requirements of sheep in semi-arid Morocco

Auteur : Boulanouar Bouchaib

Université de soutenance : University of Nebraska - Lincoln

Grade : Doctor of Philosophy (PhD) 1994

Wheat is grown in rotation with weedy fallow which is grazed during the fallow year. Sowing weedy fallow with regenerating annual medic (ley farming), was tested for its effect on sheep and cereal productions. Lamb performance was similar in both systems (Trial 1). Pastures were grazed with ewe-lambs (Trial 2). Lambs gained 65% and ewes 60% more on medic. Wool yield was 23% greater on medic. Medic biomass was similar (Trial 1) and was higher (Trial 2) than weedy fallow. Seed yield varied from 36 to 135 kg ha$\sp-1$ depending on the year. Grain and straw yields and lamb performance on stubble were similar in both systems.^ A second study, investigated the effect of NH$\sb4$OH and urea treatments and protein supplementation (fish meal and blood meal/feather meal mix) on wheat straw quality using laboratory and sheep performance evaluation. Both treatments provided 3% N at 40% moisture. IVDMD, CP, NDF, ADF and hemicellulose data showed quality improvement due to ammoniation. Treatment and supplement type did not interact in growth and digestion trials. Apparent in vivo digestibility was higher in ammonia treatment with no supplement effect. Intake, gain and feed efficiency were higher in ammonia treated straw, but were not affected by supplement type. Ammoniation increased fiber in situ extent of digestion and decreased lag time. This study showed the advantage of ammonia over urea. Performance was not affected by supplement type.^ A third study examined the effect of metabolizable protein and energy restriction on age and weight at puberty in Black and White faced ewe lambs. Lambs were fed one of three diets : control ; energy restricted ; metabolizable protein restricted. Serum was assayed for progesterone to determine age at puberty. Control lambs gained faster than restricted lambs. Lambs fed low energy gained less than lambs fed low protein diet. Diet affected age, but not weight at puberty. Genotype affected both age and weight at puberty. This study emphasized prepubertal ADG over the type of nutrient restriction ; and the importance of genotype on age at puberty. ^

Mots clés : wheat, Agronomy, ley farming, Biological sciences, Livestock


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