Effects of feed restriction and forage:concentrate ratio on digestibility, methane emission, and energy utilization by goats

Abstract

-This study was carried out to to evaluate how feed restriction and different forage:concentrate ratios affect digestibility, methane emission (using the SF 6 technique), and energy utilization of Anglo-Nubian goats. Fifteen (15) dry and non-pregnant Anglo Nubian goats, averaging 30±2.9 kg body weight, were used. The experiment was divided into two trials, the first of which was designed to study the effects of feed restriction (0% or ad libitum; 15% of feed restriction or equivalent to 85% of ad libitum intake; and 40% of feed restriction or equivalent to 60% of ad libitum intake) and the second, to study the effects of forage:concentrate (F:C) ratios (75:25, 54:46, and 25:75) in the diet. The sulfur hexafluoride (SF 6 ) tracer gas method was used to collect and estimate methane (CH 4 ) emissions. Feed restriction level did not affect apparent total tract digestibility of dry matter (DM), organic matter, crude protein, and neutral detergent fiber. Methane emission (g d −1 ) decreased linearly as intake level decreased. However, energy loss in methane proportional to organic matter intake was similar among levels of feed restriction; consequently, dietary metabolizability did not differ among treatments. Methane gas (g d −1 ) as a function of F:C ratio revealed a quadratic response, showing the highest values when animals were fed the 46:54 F:C ratio diet (18.2 g d −1 ), suggesting that the decrease in absolute CH 4 occurred when the level of concentrate inclusion in the diet surpassed approximately 50%. The results presented herein may be relevant for the ongoing and future efforts towards completion of an IPCC inventory regarding the contribution of goats to the greenhouse gas effects on the planet.

Intake, digestibility, growth performance, and enteric methane emission of Brazilian semiarid non-descript breed goats fed diets with different forage to concentrate ratios

“…This is especially true where concentrates have high starch contents. Though there remain apparent inconsistencies for goats, as witness the comparison between our results and those of Lima et al (2016) and Na et al (2017). As data have accumulated on this topic, opportunities should be taken to exploit the variation in differences among feed qualities that have been used in different experiments to interrogate cognate datasets together so as to tease out dietary variables that have major impact.…”

“…However, there were no reductions in methane emissions from goats in response to decreased forage:concentrate ratio in two recent studies, in which a corn and soybean meal-based concentrate was used (Lima et al 2016;Na et al 2017). These conflicting results could be due to differences in forage quality between studies.…”

“…The use of diets with low forage:concentrate ratio is one of the major management strategies to reduce enteric methane emissions from ruminants through changes in ruminal fermentation (Hristov et al 2013). Despite this, few studies have been conducted to evaluate the effect of different forage:concentrate ratios on enteric methane emissions in goats (Lima et al 2016;Na et al 2017).…”

Applying the California net energy system to growing goats1

“…Studies conducted in our research group traditionally use estimates of gaseous energy loss as suggested by Blaxter and Clapperton (1965) , resulting in mean value of 8.14 ± 0.433% GE ( Figure 3 ). In this matter, variation in losses due to methane are not well understood because it relies on ruminal microbiota complex interactions, which may vary accordingly feed additives, feed regimen, roughage:concentrate ratio, and measurement methodologies ( Beauchemin et al, 2008 ; Hales et al, 2014 ; Knapp et al, 2014 ; Hill et al, 2016 ; Lima et al, 2016 ; Tapio et al, 2017 ; Hristov et al, 2018 ). Considering that the energy losses in gases comprise mainly methane produced by ruminants, recent studies at UNESP ( Figure 1 ) focused on measuring methane production in goats.…”

Extratos de plantas como aditivos naturais na dieta de cordeiros em terminação

“…Os pequenos ruminantes emitem, naturalmente, menos metano por serem seletores de concentrado. A média estimada de emissão de gás metano encontrada no presente estudo foi similar a média obtida por Lima et al (2016) utilizando o método de gás traçador SF6 em cabras. observaram redução na emissão de metano (cerca de 13%) quando utilizaram 41 g/kg MS da dieta de Acacia mearnsii para ovelhas, redução essa semelhante ao presente estudo.…”