Abstract The objective of this work was to evaluate the effect of diets with cottonseed and vitamin E on the greenhouse gas (GHG) emissions of cattle feces analyzed in biodigesters. Animal feces were evaluated in 18 laboratory-scale anaerobic digesters through the following treatments: control, feces from cows fed with a control diet; CS, feces from cows fed with a cottonseed diet; and CSVitE, feces from cows fed with a cottonseed and vitamin E diet. The production of biogas and GHG was measured, and no differences were observed for the emissions of biogas, methane (CH4), and nitrous oxide (N2O). The partition of the gross energy of the anaerobic digestion process was similar among treatments. On average, 28% of gross energy fed was released as CH4, 47% during digestion, and 25% as other gases and heat. The addition of cottonseeds to the cattle diet increases the concentration of CH4 and reduces that of CO2, but it does not affect the total production of CH4, CO2, and N2O in the biodigesters. The inclusion of vitamin E in the diet has no effect on GHG production in the biodigesters.

Resumo O objetivo deste trabalho foi avaliar o efeito de dietas com caroço de algodão e vitamina E nas emissões de gases de efeito estufa (GEE) de fezes de bovinos analisadas em biodigestores. As fezes dos animais foram avaliadas em 18 digestores anaeróbios de laboratório, por meio dos seguintes tratamentos: controle, fezes de vacas alimentadas com dieta controle; CS, fezes de vacas alimentadas com caroço de algodão; e CSVitE, fezes de vacas alimentadas com caroço de algodão e vitamina E. As produções de biogás e GEE foram medidas, e não foram observadas diferenças para as emissões de biogás, metano (CH4) e óxido nitroso (N2O). A partição da energia bruta do processo de digestão anaeróbica foi semelhante entre os tratamentos. Em média, 28% da energia bruta alimentada foi liberada como CH4, 47% na digestão e 25% como outros gases e calor. A adição de caroços de algodão na dieta de bovinos aumenta a concentração de CH4 e reduz a de CO2, mas não afeta a produção total de CH4, CO2 e N2O nos biodigestores. A inclusão de vitamina E na dieta não tem efeito na produção de GEE nos biodigestores.

ABSTRACT: Inherently, ruminant production of methane (CH4), a greenhouse gas (GHG), causes animal energy losses. Cottonseed is a lipid source and is used sometimes to enhance energy density in cattle diets. It also can mitigate enteric CH4. Lipids release peroxides in the rumen, and antioxidants have the ability to neutralize them. Thus, a lipid and antioxidant source can benefit rumen fermentation. The aim of this study was to evaluate rumen fermentation parameters from cows fed cottonseed and vitamin E. Six cannulated cows were arranged in a replicate 3 × 3 latin square. Treatments were: 1) Control, 2) CS (30 % corn replaced by cottonseed) and 3) CSVitE (30 % corn replaced by cottonseed, plus 500 IU VitE). Results were compared by orthogonal contrast. When compared to the control diet, cottonseed inclusion reduced enteric CH4 emissions by 42 %. Production of acetate, butyrate and the acetate to propionate ratio were respectively 34 %, 47 % and 36 % lower with the cottonseed treatments. Energy lost in the rumen as CH4 and energy release as butyrate were reduced by 26 % and 32 % respectively. Propionate and intestinal energy release were, respectively, 43 % and 35 % higher with cottonseed treatments. Furthermore, as a nutritional strategy to mitigate enteric CH4, cottonseed has positive effects on short chain fatty acid (SCFA) production and gastrointestinal energy release. Vitamin E did not result in improvements in ruminal fermentation. Further studies evaluating levels of vitamin E in association with different amounts and sources of lipids are required.

ABSTRACT: High lipid concentration in ruminant diets often harms nutrient digestibility and feed intake; thus, a protected lipid and antioxidant source can be considered as an alternative for improving diet energy without putting animal production at a disadvantage. The aim of this study was to evaluate the dry matter intake (DMI), nutrient digestibility and feeding behavior of cattle fed cottonseed and vitamin E. Six cannulated cows, non-pregnant, non-lactating were distributed in a replicated 3 × 3 Latin Square design. Feed was offered ad libitum twice daily. Treatments were: 1) Control, 2) CS: 30 % cottonseed included; and 3) CSVitE: 30 % cottonseed plus 500 IU VitE included. Data were analyzed by SAS (Statistical Analysis System, v.9.3) and the significance was declared at p < 0.05. Diets with cottonseed had 22 % greater digestibility of ether extract and 9 % lower digestibility of non-fiber-carbohydrates compared to the control. Treatments with cottonseed had 13 % higher time eating, 48 % more ruminating, 34 % more chewing and 17 % lower time idling compared to the control. Molar proportion of propionate was 36 % higher and the butyrate and acetate:propionate ratio were 27 % and 30 % lower, respectively, for the cottonseed treatments compared to the control. Including cottonseed up to 30 % can be used to increase diet energy density leading to improvements in feeding behavior and ruminal parameters. The inclusion of Vitamin E did not result in benefits to cattle when it was combined with cottonseed. Further studies should be undertaken to evaluate vitamin E levels in association with different amounts and lipid sources.