Energy partitioning and methane emission by sheep fed sorghum silages at different maturation stages

Abstract

Energy partitioning and methane production by sheep fed silages of three commercially available sorghum hybrids (BRS 610, BR 700 and BRS 655) harvested at three maturation stages (milk, soft dough and floury) were evaluated in open circuit respiration chambers. A complete randomized design was used in a 3 × 3 (hybrids × maturity stages) factorial arrangement, and the means were compared by the Student-Newman-Keuls (SNK) test (P<0.05). The intake of dry matter, digestible dry matter, gross energy, digestible energy and metabolizable energy were not affected by maturation stage, but were influenced by hybrid. The net energy intake was influenced by maturity and sorghum genetics. The fecal output represented the main source of energy loss, as percentage of gross energy intake (48% to 52%), followed by heat increment (10% to 19%), methane emissions (4% to 6%) and urine (1% to 2%). There were no differences (P>0.10) among the treatments for the apparent digestibility of gross energy and metabolizability (q m ). An interaction (P<0.05) between sorghum hybrid and maturation stages was observed for the efficiency of metabolizable energy utilization for maintenance (km), which ranged between 0.53 and 0.78. No differences (P>0.10) among treatments occurred in the daily methane production. There is substantial genetic diversity within sorghum species, determining different nutritional values. Sorghum genetics and maturity at harvest should not be an opportunity to reduce the contribution of agriculture to methane emissions.Keywords: greenhouses gas, nutritional value, net energy, respirometry RESUMO A partição de energia e a produção de metano por ovinos alimentados com silagens de três híbridos de sorgo comerciais (BRS 610, BR 700 e BRS 655), colhidos em três estádios de maturação (leitoso, pastoso e farináceo), foram avaliadas em câmaras respirométricas de circuito aberto. Utilizou-se delineamento inteiramente ao acaso, em arranjo fatorial 3 x 3 (híbridos x estádios de maturação), e as médias foram comparadas pelo teste Student-Newman-Keuls (SNK) (P<0,05). Os consumos de matéria seca, de matéria seca digestível, de energia bruta, de energia digestível e de energia metabolizável não foram afetados pelo estádio de maturação, mas foram influenciados pelo híbrido de sorgo. O consumo de energia líquida foi influenciado pela maturidade e pelo híbrido. As perdas de energia nas fezes representaram a principal fonte de perda energética como porcentagem do consumo de energia bruta (48% a 52%), seguida pelo incremento calórico (10% a 19%), pela emissão de metano (4% a 6%) e pela urina (1 a 2%). Não houve diferenças (p>0,10) entre os tratamentos para a digestibilidade aparente da

Silage quality of six sorghum cultivars for sheep

“…The apparent digestibility of dry matter and that of organic matter were not affected by the tested cultivars, differently from what was observed during the in vitro experiment. The apparent digestibility values in the present study were similar to those found in the literature, both in tropical and temperate conditions (Miron et al, 2007;Machado et al, 2015).…”

Energy value of babassu cake as substitute bulk in sheep diets

“…Neither gross energy (GEI) nor net energy (NEI) intake was affected by the diets (P>0.05) (Table 3). According to Machado et al (2015), GEI has a high correlation with dry matter intake (DMI) in kg DM kg -0.75 (DMI x GEI = 0.997) (P<0.0001). Studying the nutritional value of diets with increased added babassu cake, no effect was found on the DMI of the animals (Y = 63.79 + 9.37 g kg -0.75 ) (P>0.05), which partially explains the GEI not being affected, since the levels of GE in the diets did not vary.…”

“…To calculate the energy lost in the form of methane in grams per day (g day -1 ), grams per kilogram of ingested dry matter (g kg -1 DM), and kilocalories per kilogram of ingested dry matter (kcal kg -1 DM), a value of 13.334 kcal g -1 and density of 0.7143 g L -1 was considered (Machado et al, 2015).…”

“…The energy content of the diet is one of the main determinants of animal production, and knowledge of the energy efficiency of diets is essential (López & Fernández, 2013). The energy generated by the oxidation of nutrients in the organism of the animal can be used to maintain vital processes or to carry out work (Machado et al, 2015). The gross energy content of the diet should not be used to balance the diet, due to variations in digestibility and metabolism.…”

“…The energy retained in body tissue or used in production is calculated as the difference between the total gross energy intake and the energy lost through faeces, urine and gases, and in heat production (Machado et al, 2015). Methane production by ruminants is directly related to the efficiency of use of the digestible energy (Ribeiro et al, 2015), and because it is an important greenhouse gas (Grainger & Beauchemin, 2011;Tangjitwattanachai, Phaowphaisal, & Sommart, 2015), studies that determine methane emission by ruminants are extremely important, and aid in the adoption of managements that improve the efficiency of use of the diet.…”