Effect of ruminal escape protein and fat on nitrogen utilization in lambs exposed to elevated ambient temperatures.
Eight wether lambs (mean BW = 28.8 kg) with ruminal and abomasal cannulas were assigned to either thermally neutral or high ambient temperature treatments. Within each temperature, lambs were randomly allotted to dietary treatments consisting of a basal diet (60% corn and 24% cottonseed hulls) either with (high; 11.4% CP) or without (control; 10.1% CP) added ruminal escape CP as fish meal and with (high) or without (control) 5% added ruminally inert fat in a 2 x 2 factorial treatment arrangement using a Latin square design. Lambs were fed 606 g of DM/d in each period, which consisted of a 10-d adjustment followed by 6 d of sample collection. High temperature increased (P less than .05) respiration rate, evaporative water loss, and rectal temperature. When compared with controls, lambs fed high escape CP retained more N when exposed to high temperatures (2.8 vs 3.6 g of N/d) and less N at neutral temperatures (3.3 vs 3.1 g of N/d; temperature x escape CP; P less than .05). Retention of N was greater (P less than .05) in lambs fed high than in those fed control fat (3.8 vs 2.7 g/d). Lambs fed high vs control escape CP had greater abomasal feed N flow (percentage of intake) when fed high-fat diets (77.3 vs 56.1%) but similar dietary N flow when fed control fat diets (55.8 vs 54.3%; fat x escape CP; P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)
Bunting
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Department of Dairy Science, Louisiana State University Agricultural Center, Baton Rouge 70803.
Sticker
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Wozniak
P J
PJ
D000018:Abomasum / Q000502:physiology; D000596:Amino Acids / Q000378:metabolism; D000821:Animal Feed; D000818:Animals; D001833:Body Temperature Regulation; D004041:Dietary Fats / Q000008:administration & dosage* / Q000378:metabolism; D004043:Dietary Fiber / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D004063:Digestion; D004326:Drinking; D004435:Eating; D005285:Fermentation; D006358:Hot Temperature / Q000009:adverse effects; D007420:Intestine, Large / Q000502:physiology; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D012119:Respiration; D012417:Rumen / Q000502:physiology; D012756:Sheep; D012757:Sheep Diseases / Q000378:metabolism*; D013312:Stress, Physiological / Q000378:metabolism / Q000662:veterinary*
D000596:Amino Acids; D004041:Dietary Fats; D004043:Dietary Fiber; D004044:Dietary Proteins; D009584:Nitrogen