Energy, nitrogen partitioning, and methane emissions in dairy goats differ when an isoenergetic and isoproteic diet contained orange leaves and rice straw crop residues

Abstract

The aim of this study was to evaluate the effects of incorporating rice straw and orange leaves into the diets for goats. Ten Murciano-Granadina goats at mid lactation weighing 45 ± 0.3 kg were used in a crossover design. Two isoproteic and isoenergetic diets (180 g/kg DM and 17 MJ/kg DM, respectively) with alfalfa hay as forage source (33% of DM) were fed. A control diet (CON) incorporated barley as energy source and soy hulls as fiber component. The experimental diet (ORG) replaced barley and soy hulls with orange leaves (19% on DM basis), rice straw (12%, on DM basis) and soya oil (2%). Peas and horsebeans were the protein source in both diets. Each goat received the 2 treatments in 2 periods. Goats were fed the experimental diets and after 14 d on their respective treatments moved to individual metabolism cages for another 7 d. Subsequently, feed intake, total fecal and urine output and milk yield were recorded daily over the first 5 d. During the next 2 d ruminal fluid and blood samples were collected, and then individual gas-exchange measurements were recorded by a mobile open-circuit indirect calorimetry system using a head box. No differences in dry matter intake were detected, and apparent total-tract digestibility was greater in CON than ORG. Efficiency of metabolizable energy intake for milk and maintenance also was lower in response to ORG (0.65 vs. 0.63), with energy balance being negative (−12 kJ/kg of BW 0.75 ) due to mobilization of fat (−16 g/animal vs. 68 g/animal for ORG and CON, respectively). Although actual milk yield was lower in goats fed ORG (2.32 vs. 2.06 kg/d, respectively), energy-corrected milk did not differ (2.81 kg/d on average). In terms of milk quality, milk fat content, and concentrations of monounsaturated (18.54 vs. 11.55 g/100 g milk fat) and polyunsaturated fatty acids (5.75 vs. 3.99 g/100 g milk fat) were greater in goats fed ORG. Based on various indices, the milk produced by ORG would be less atherogenic and thrombogenic than CON milk. Compared with CON, enteric CH 4 emission was lower due to feeding ORG (reduction of 38 g CH 4 /kg milk fat). Data suggest that greater fat mobilization in goats fed ORG might have been due to the apparent lack of synchrony between degradable protein and carbohydrate and the lipogenic nutrients associated with the lower cereal content of the ORG diet. Thus, goats fed ORG seemed to rely more on fat depots to help meet energy requirements and reach optimal performance. As such, the lower content of glucogenic nutrients in ORG did not favor body fat deposition and partitioning of ME into body tissue. Overall, responses in terms of CH 4 emissions and milk quality suggest that inclusion of rice straw and orange leaves in diets for small ruminants could be a valuable alternative to reuse, recycle and revalue agricultural by-products.

Intake, digestibility, milk production, ingestive behavior and gas emissions of Saanen goats fed pornunça silage with levels of condensed tannin extracted from Schinopsis brasiliensis

“…Since dairy production is a highly energy-dependent metabolic process (Goetsch, 2019), the reduction in the emission of gases can improve the animal energy balance. Because the formation of methane is a mechanism of hydrogen elimination from the rumen, but it is accompanied by carbon loss (Beauchemin et al, 2020), promoting energy loss (2 and 12% of the crude energy) of the goats feed intake (Fernández et al, 2021).…”

Nutrigenomics in livestock: potential role in physiological regulation and practical applications

“…crop residues, agro-industrial byproducts) to livestock have or are becoming important in the management at the farm underscores the potential nutrigenomics effect of diets fed to livestock. Although agro-industrial byproducts such as grape marc and citrus leaves in ruminant diets have received special focus for their potential role in altering methane emissions (Moate et al 2014;Fernández et al 2021), they contain molecules such as polyphenols and essential oils, which could have a nutrigenomics effect at the tissue level.…”

Potential of Agroindustrial By-Products to Modulate Ruminal Fermentation and Reduce Methane Production: In Vitro Studies

“…In addition, by-products can contain multiple nutrients and bioactive compounds that could improve the quality of animal products and the health of the animal itself [ 6 ], and some of them may be effective at decreasing enteric methane emissions [ 7 , 8 ]. Therefore, increasing the practical use of agroindustrial by-products in ruminant feeding will reduce their negative environmental impact, and might decrease methane emissions associated with the livestock sector which is another proposed objective to fight climate change [ 9 ].…”