Author:
Zanetti D.,Godoi L. A.,Estrada M. M.,Engle T. E.,Pacheco M. V. C.,Pereira J. M. V.,Detmann E.,Paulino M. F.,Valadares Filho S. C.
Abstract
We measured nutrient intake and digestibility, performance and mineral status of young Nellore bulls fed three diets with and without supplementation comprising calcium (Ca), phosphorus (P) and micro-minerals during the growing and finishing phases. Five bulls were slaughtered at the beginning of the experiment to measure initial mineral status. Forty-two young Nellore bulls (initial bodyweight (mean ± s.d.) 270.4 ± 36.6 kg, age 8 months) were assigned for 125 days to one of six treatments: sugarcane as a roughage source plus a concentrate based on soybean meal and soybean hull with (SH100) and without (SH0) supplementation; sugarcane as a roughage source plus a concentrate based on soybean meal and ground maize with (SC100) and without (SC0) supplementation; and maize silage as a roughage source plus a concentrate based on soybean meal and maize with (CS100) and without (CS0) supplementation. The experiment was conducted as a completely randomised design with a 3 × 2 factorial arrangement of treatments. Nutrient intake and digestibility, bone and serum parameters related to Ca and P metabolism, and liver mineral concentrations were measured. Nutrient intake, digestibility and performance were not affected (P > 0.10) by the mineral factor. Water intake was higher (P < 0.05) with SH100 than with all other diets. Rib-bone breaking strength and density according to dual-energy X-ray absorptiometry were reduced (P < 0.04) in the absence of supplementation. Metatarsus parameters were not affected (P > 0.10). Liver copper (Cu) content was reduced (P < 0.01) in diets without supplementation. In conclusion, the short-term absence of mineral supplementation did not influence intake and digestibility. However, depending on diet type, absence of Cu may reduce the hepatic Cu content, and a low Ca:P ratio may stimulate bone reabsorption without compromising performance. Therefore, under our conditions, mineral requirements are overestimated by nutritional systems.
Subject
Animal Science and Zoology,Food Science
Cited by
3 articles.
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