• Energy Research

The disposal of chemical waste and the precision of analyses of the neutral (NDF) and acid (ADF) detergent fiber contents were evaluated utilizing conventional (Van Soest) and alternative methods of analyses. The recovery of acetone promoted both economic and environmental gains, with a recovery rate of 84.12%. The precision of the analyses was not observed in most of the determinations with reutilization of chemical waste in all the analytical methods tested, in spite of promoting decrease in cost, time invested in the preparation of solutions and the disposal of chemical waste.

The aim of this study was to determine the effects of different amounts of crude glycerol (CGL) on dry matter intake, milk yield, milk protein yield, and milk fatty acid profile of dairy cows grazing on a Kikuyu-based pasture. Six Holstein cows were used in the first third of lactation (mean ± SD 559 ± 22.5 kg body weight, 43 ± 10 days in milk, and 26.8 ± 1.2 kg milk/day) and were randomized within a replicated 3 × 3 Latin square arrangement. Animals grazed the Kikuyu grass and were supplemented with a commercial energy-protein concentrate at 1.0 kg/4.0 kg of milk. The experimental period was 69 days. The following treatments were administered: CGL0 (control, without glycerol), CGL1 (750 g/cow/day), and CGL2 (1,500 g/cow/day). The addition of 750 and 1,500 g of CGL did not affect grass and concentrate intake (P > 0.05). However, milk yield (FCM 3.5%) increased by 14.2% in the CGL2 group compared to that obtained in the control group (CGL0) (P = 0.02). The addition of 1,500 g of CGL to the diet resulted in a 2.1% greater yield of milk protein compared to that obtained with CGL0 treatment (P = 0.01). Further, the addition of 1,500 g of CGL did not impact grass intake, milk fat concentration, or fatty acid composition (P < 0.05). Thus, the inclusion of CGL as a co-product may be a nutritional strategy to increase the productivity of dairy production systems in tropical perennials, such as Kikuyu grass.

SummaryPrevious research on energy requirements of female Saanen goats, using the factorial approach, has not considered the specific requirements for maintenance and growth during the pubertal phase. Thus, the purpose of this study was to estimate energy requirements for maintenance (Trial 1) and growth (Trial 2) of non‐pregnant and non‐lactating female Saanen goats at the pubertal phase from 30 to 45 kg. In Trial 1, the net energy requirements for maintenance (NEm) were estimated using 18 female Saanen goats randomly assigned to three levels of intake: ad libitum, and 70% and 40% of ad libitum intake. These animals were pair‐fed in six slaughter groups, each consisting of one animal for each level of intake. In Trial 2, the net energy requirements for growth (NEg) were estimated using 18 female Saanen goats, which were fed ad libitum and slaughtered at targeted BW of 30, 38 and 45 kg. The NEm was 52 kcal/kg0.75 of BW. The NEg increased from 3.5 to 4.7 Mcal/kg of BW gain as BW increased from 30 to 45 kg. Our results suggest that the guidelines of the major feeding systems for the entire growth phase may not be adequate for females at pubertal phase.

Abstract Integrated Systems (IS) have been identified as an efficient land-management strategy for restoring degraded areas worldwide, increasing crops and beef yields and providing technical potential for carbon (C) sequestration in soil and trees as an option for offsetting CH 4 and N 2 O emissions from cattle production. The aim of our study is to estimate the greenhouse gas (GHG) balance and the C footprint of beef cattle (fattening cycle) in three contrasting production scenarios on the Brachiaria pasture in Brazil—1) degraded pasture (DP), 2) managed pasture (MP), and 3) the crop-livestock-forest integrated system (CLFIS)—presenting new alternatives of land use as a GHG mitigation strategy. Area-scaled total GHG emissions were highest in MP (84,541 kg CO 2 eq ha −1 ), followed by CLFIS (64,519 kg CO 2 eq ha −1 ) and DP (8004 kg CO 2 eq ha −1 ) over a 10-yr period. Our results note that the highest C footprint of beef cattle was in the DP, 18.5 kg CO 2 eq per kg LW (live weight), followed by 12.6 kg CO 2 eq per kg LW in the CLFIS and 9.4 kg CO 2 eq per kg LW in the MP, without taking into account the technical potential for C sequestration in MP (soil C) and CLFIS (soil and Eucalyptus C). Considering the potential for soil C sequestration in the MP and CLFIS, the C footprint of beef cattle could be reduced to 7.6 and −28.1 kg CO 2 eq per kg LW in the MP and CLFIS, respectively. The conversion of the degraded pasture to a well-managed pasture and the introduction of CLFIS can reduce their associated GHG emissions in terms of kg CO 2 eq emitted per kg of cattle LW produced, increasing the production of meat, grains and timber. This reduction is primarily due to pasture improvement and increases in cattle yields and the provision of technical potential for C sinks in soil and biomass to offset cattle-related emissions.

An in vitro trial was conducted to evaluate the effects of different unsaturated fatty acids (UFA) sources plus crude glycerin (CGL) on gas production and rumen biohydrogenation (RBH). Incubated diet corresponded to diets containing corn silage (30%) and concentrate (70%) composed of corn, urea, mineral salts, CGL, and different UFA sources as follows: no additional fat (NAF), rumen protected fat (RPF), soybean oil, linoleic acid (LA) or alpha-linolenic acid (LN). Methane concentrations in LA and LN were lower compared to NAF (p < 0.001), but when CH4 was expressed as a proportion of total gas, NAF and RPF showed the greatest values among evaluated UFA sources (p = 0.001). 18:1 t11 concentration showed a faster increase from 0 to 1 h and a slower decrease from 1 to 36 h of incubation, irrespective of UFA source. A higher C18:1 t11 production rate was observed from 1 h to 5 h of incubation, where LA and LN have higher values compared to NAF and RPF diets (p < 0.001). Diets with a high content of LA may be efficient as a nutritional approach to reduce methane production and RBH, resulting in positive effects on vaccenic acid concentrations.

Supplementation of grass-fed cattle with low-cost feeding alternatives may be an attractive way to improve efficiency of cattle production. We hypothesized that inclusion of crude glycerin (CG) in supplements provided to grass-fed cattle could improve feed conversion without negative effects on growth performance while reducing methane emissions. Our hypothesis was tested using Nellore bulls grazing tropical pasture ( = 50; initial BW of 427 ± 19.41 kg; age of 17 ± 2 mo) supplemented with increasing concentrations (0, 70, 140, 210, and 280 g/kg DM basis of supplement) of CG and corn gluten replacing corn grain. A second experiment was conducted using 10 ruminally cannulated Nellore steers (490.1 ± 47.8 kg BW; age of 25 mo) to assess the impact of different concentrations of glycerin in the supplement on ruminal VFA concentration. Inclusion of CG did not affect total DMI ( = 0.53), DMI of forage ( = 0.41), supplement DMI ( = 0.47), organic matter intake ( = 0.50), crude protein intake ( = 0.24), NDF intake ( = 0.49), GE intake ( = 0.50), NDF digestibility ( = 0.17), final BW ( = 0.17), LM area ( = 0.50), rib fat thickness ( = 0.87), or carcass gain ( = 0.13). The inclusion of CG in the supplement linearly increased ( < 0.001) the molar proportion of propionate, butyrate, and valerate; linearly decreased acetate ( = 0.001); and did not affect the molar proportion of isovalerate ( = 0.31) and isobutyrate ( = 0.63), thereby reducing the acetate to propionate ratio ( < 0.001). The increase of CG supplementation of young bulls in pasture had a quadratic effect on BW gain ( = 0.002), with lower BW gain with 140 g/kg DM of CG in the supplement and tended ( = 0.06) to improve G:F. Inclusion of CG did not affect ruminal CH emission expressed in kilograms per year ( = 0.74), grams per kilogram of DMI ( = 0.69), and grams per kilogram of carcass gain ( = 0.48). Crude glycerin supplementation was not effective as a strategy to reduce CH emission in grass-fed cattle. However, CG can be effectively used as a partial energy source in supplement of grazing cattle, promoting an improvement in feed efficiency.