Dinâmica do fósforo em ovinos alimentados com dietas contendo diversos níveis deste mineral

Abstract

RESUMO -Avaliou-se a dinâmica do fósforo no organismo de cordeiros Santa Inês alimentados com dietas com diversos níveis deste mineral, considerando as correlações entre os níveis de fósforo consumido e de fósforo no plasma; na saliva; no conteúdo ruminal; nas fezes; e na urina. Foram utilizados 18 cordeiros com 5 meses de idade e 27 kg de peso vivo. O experimento foi dividido em dois períodos de cinco semanas, cada um com nove animais. Os animais foram mantidos individualmente em gaiolas para estudo de metabolismo e receberam uma dieta basal constituída de feno de capim coast-cross (Cynodon dactylon, L. Pers.) e concentrado com diferentes níveis de fósforo (1,9; 2,6; 3,3 g/dia) provenientes de fosfato bicálcico. No 15 o dia, iniciaram-se as coletas de saliva, plasma, conteúdo ruminal, fezes e urina para as análises de fósforo inorgânico. Observaram-se correlações positivas entre o aumento do consumo de fósforo e os teores desse mineral no plasma (r = 0,64), na saliva (r = 0,86), no conteúdo ruminal (r = 0,82), nas fezes (r = 0,92) e na urina (r = 0,37), comprovando que, quando absorvido, o fósforo é distribuído no corpo pelo plasma. Após a saturação no organismo, o excesso é secretado via saliva, segue para o rúmen e, ao chegar ao intestino, é reabsorvido em menor quantidade e excretado via fezes. À medida que se aumentaram os níveis de fósforo na dieta, verificou-se aumento expressivo dos teores desse mineral na saliva, no plasma, no conteúdo ruminal e nas fezes.Palavras-chave: cordeiros Santa Inês, níveis de fósforo, nutrição animal, ruminantes Dynamics of phosphorus in the body of sheep fed different levels of this mineral in the dietsABSTRACT -The dynamics of phosphorus in the body of Santa Ines lambs fed diets with different levels of this mineral was evaluated, considering the correlations among the levels of phosphorus consumed, in plasma; in saliva, in rumen contents, in feces, and in urine. Eighteen lambs were used with five mo old and 27 kg BW. The experiment was divided into

Minimum Effects of Sampling Time on the Apparent Digestibility of Nutrients and Blood Protein Catabolites in Light Lambs

“…The P apparent digestibility in the growing period was lower in the CP20 group than in CP18 group. Borges et al [ 24 ] noted that P digestibility depends on its diet content, nutrient sources and physiological status. Furthermore, it has been described that faeces are the principal pathway of P excretion in ruminants, and it is directly correlated with the diet P content [ 24 ].…”

“…Borges et al [ 24 ] noted that P digestibility depends on its diet content, nutrient sources and physiological status. Furthermore, it has been described that faeces are the principal pathway of P excretion in ruminants, and it is directly correlated with the diet P content [ 24 ]. However, according to Dias et al [ 25 ], the faecal loss of P may be overestimated because of salivary P secretion, suggesting that the true available P was probably greater in both dietary treatments.…”

“…Assuming that the urinary loss of this mineral is minimal, the metabolic P requirements may be related to the mineral proportion of skeletal body weight gain [ 26 ]. As these lambs had similar average daily gain, the greater P apparent digestibility in CP18 lambs compared to CP20 lambs may be the result of a slightly higher dietary concentration of this nutrient (0.45% vs. 0.42%, respectively) and a lower salivary P secretion to buffer rumen pH conditions, which can represent as much as 80% of the endogenous secretion in the rumen [ 24 ]. On the contrary, in the finishing period, no differences were observed in OM, CP and P apparent digestibility between experimental diets, which suggests that the CP17 group met its nutritional requirements to a greater extent.…”