Caracterização florística da pastagem nativa da caatinga e efeitos de aditivos sobre o consumo, emissão de metano e desempenho de ovinos

Abstract

The aim was to evaluate the effect of additives at sheep in native pasture of Caatinga in the wet season on the intake, methane emission, performance and carcass characteristics. The treatments were compused by additives, to know: without additive, control; S-CT, addition of the ZnSO4.7H2O and availability of 22.5% of Zn (S-Zn) added on mineral salt (with composition, Ca = 82.0 g, Co = 30.0 mg, Cu = 350 mg, Cr = 11.7 mg, S = 11.7 g, P = 60.0 g, I = 50.0 mg, Mn = 1200 mg, Mo = 180 mg, Se = 15 mg, Na = 132 g e Zn = 2600 mg, by kg of product) and addition of propylene glycol (PG; S-PG). Evaluation of consumptions and measurement of the methane enteric emissions in four periods (mounths, March, April, May, June/2014) on the rainfall season, were carried. Twenty-four sheep, crossbreed Santa Ines, males, weight initial 19.3 ± 2.52 kg, 4-mo old, being 8-replications by treatments, assigned in a randomized design, were used. There was no effect of the additives, and additive x period interaction for the consumptions (P>0.05). Between periods, the OM intake was in average 23.9% higher in March compared to June. For CP intake there was a decrease in consumption, month to month (P<0.05). The intake of fibrous fractions in the periods was higher in March (P<0.05). There was a higher CH4 emission g d-1 to S-PG compared to S-CT and S Zn (P<0.05). In the periods, there was higher OMI and NDFI in March, and higher CH4 emission g day-1 in the month of May compared to June, well as, CH4 emission in g OM-1 ingested (g day-1 and g kgLW0.75 d-1; P<0.05). The additives did not affect the performance, and the parameters of carcass and cuts commercials (P>0.05). There was not effects of the additives for organoleptic traits, and aspects physic-chemical of the meat (P>0.05). The supply of the additives Zn and PG, does not provide increase on nutrient's intake by sheep in Caatinga native pasture. The Caatinga native pasture presents biomass with high contents of crude protein and organic matter digestible, on rainfall season. However, there is a decrease of the intake by the sheep, due the decline of the quality, mainly of digestible organic matter and, in the availability of the pasture, which was affected by drought in the last months. The technique of the double-marker, LIPE® and lignin Klason on the model proposed provides adequate estimates of the intake differentiated The results of this study suggest that the additives do not showed beneficial effect to mitigate the CH4 emission by sheep. The CH4 emissions by sheep finished in native pasture of the Caatinga are affecteds by the rainfall season due the fluctuations, in both, availability and in quality of the pasture. The additives, ZnSO4.7H2O, like source of dietetic zinc and the PG no provides improvement on performance and in the meat and carcass characteristics of sheep finished in native pasture of Caatinga.