Aditivos naturais em dietas para terminação de cordeiros em confinamento

Abstract

This thesis aimed to: address the use of natural additives as modulators of the ruminal fermentation process and their influence on carcass characteristics and meat quality (Chapter I); evaluate the effects of increasing doses of copaiba oleoresin and dried barbatimão bark in association with diets containing different proportions of concentrate on the rumen fatty acid profile in an in vitro ruminal fermentation assay (Chapter II); evaluate the inclusion of copaiba oleoresin in the diet and its effects on carcass characteristics and meat quality of feedlot-finished lambs (Chapter III); determine the possible effects of natural additives derived from barbatimão bark on carcass characteristics and meat quality of feedlot-finished lambs (Chapter IV). Chapter I was based on studies published in the literature reporting on plant biocompounds as ruminal modulators and their possible effects on carcass characteristics and meat quality. It was found that these compounds have potential use in ruminant nutrition, as they improve the ruminal fermentation process and the final quality of products, due to their antimicrobial and antioxidant properties. In Chapter II, two in vitro experiments were conducted, where four levels of copaiba oleoresin were evaluated: (OC0 - 0 µl of CO/100 mg of incubated DM; OC1 - 0.060 µl of CO/100 mg of incubated DM; OC2 - 0.120 µl of CO/100 mg of incubated DM; and OC3 - 0.180 µl of CO/100 mg of incubated DM) and four levels of ground barbatimão bark (BB0 - 0 g of GB/100 mg of incubated DM; BB1 - 0.00013 g of GB/100 mg of incubated DM; BB2 - 0.00020 g of GB/100 mg of incubated DM; and BB3 - 0.00027 g of GB/100 mg of incubated DM) in diets with increasing concentrate levels (20, 50, and 80%) on the rumen short-chain fatty acid (SCFA) profile. The molar proportion of propionate decreased linearly with increasing levels of CO and BB (P<0.05). The acetate:propionate ratio increased linearly with increasing levels of BB (P=0.029). In this in vitro study, propionate-producing bacteria were the most affected, demonstrating that the inclusion of the biocompounds present in copaiba oleoresin and dried barbatimão bark were not able to improve the beneficial processes of ruminal fermentation. In Chapter III, twenty-four Pantaneira breed lambs at 152 days of age and 21.2 ± 3.9 kg of initial body weight were distributed in a randomized block design with three treatments (LAS - 0.019 g of sodium lasalocid/kg of diet; OC05 - 0.5 ml of copaiba oleoresin/animal/day; OC1 - 1.0 ml of copaiba oleoresin/animal/day) and eight replications. Hot carcass weight, cold carcass weight, and cold carcass yield were higher (P<0.05) in LAS and OC1 compared to OC05. Carcasses from LAS had higher fatness scores (P<0.05) compared to OC05. Inclusions of OC05 and OC1 in the diet reduced (P<0.05) the final pH values of carcasses. The concentration of gondoic acid (C20:1), eicosadienoic acid (C20:3n-3), and dihomo-α-linolenic acid (C20:2n-6) differed depending on the addition of CO in the diet. Overall, the concentration of these fatty acids in meat was higher with the addition of LAS compared to OC05 and OC1. Other parameters related to the meat fatty acid profile were not affected by treatments (P>0.05). The results of this study indicated that copaiba oleoresin can replace sodium lasalocid in the diet of finishing lambs without negatively impacting carcass characteristics and meat quality. As for Chapter IV, twenty-four non-castrated male Pantaneira lambs with an initial body weight of 21.2 ± 3.6 kg and 150 ± 4.5 days of age were distributed in a randomized block design with three treatments: 1.50 g/animal/day of dried barbatimão bark (BB); 0.300 g/animal/day of hydroalcoholic extract from barbatimão bark (HEB); and 0.018 g/animal/day of sodium lasalocid (LAS). Carcass characteristics were not influenced (P>0.05) by treatments, except for fatness score (P=0.010), where LAS showed higher values than HEB, but similar to BB, which in turn did not differ from HEB. Meat quality parameters such as meat color were influenced by treatments, where the yellow intensity and Hue angle values of LAS and BB were higher than those of HEB (P<0.05). Regarding the meat fatty acid profile, there was no difference between treatments (P>0.05). Based on this, this study demonstrated that natural additives derived from barbatimão bark can replace sodium lasalocid without negatively impacting lamb carcass characteristics and meat quality.