Publications by authors named "Roger S Hegarty"

A dose-response experiment was designed to examine the effect of 3-nitrooxypropanol (3-NOP) on methane (CH4) emissions, rumen function and performance of feedlot cattle fed a tempered barley-based diet with canola oil. Twenty Angus steers of initial body weight (BW) of 356 ± 14.4 kg were allocated in a randomized complete block design.

View Article and Find Full Text PDF

Variation in nutrition is a key determinant of growth, body composition, and the ability of animals to perform to their genetic potential. Depending on the quality of feed available, animals may be able to overcome negative effects of prior nutritional restriction, increasing intake and rates of tissue gain, but full compensation may not occur. A 2 × 3 × 4 factorial serial slaughter study was conducted to examine the effects of prior nutritional restriction, dietary energy density, and supplemental rumen undegradable protein (RUP) on intake, growth, and body composition of lambs.

View Article and Find Full Text PDF

Increasingly countries are seeking to reduce emission of greenhouse gases from the agricultural industries, and livestock production in particular, as part of their climate change management. While many reviews update progress in mitigation research, a quantitative assessment of the efficacy and performance-consequences of nutritional strategies to mitigate enteric methane (CH) emissions from ruminants has been lacking. A meta-analysis was conducted based on 108 refereed papers from recent animal studies (2000-2020) to report effects on CH production, CH yield and CH emission intensity from 8 dietary interventions.

View Article and Find Full Text PDF

This experiment investigated phenotypic and genetic relationships between carbon dioxide production, methane emission, feed intake, and postweaning traits in Angus cattle. Respiration chamber data on 1096 young bulls and heifers from 2 performance recording research herds of Angus cattle were analyzed to provide phenotypic and genetic parameters for carbon dioxide production rate (CPR; n = 425, mean 3,010 ± SD 589 g/d) and methane production rate (MPR; n = 1,096, mean 132.8 ± SD 25.

View Article and Find Full Text PDF

Nitrate ( ) supplementation is an effective methane (CH ) mitigation strategy for ruminants but may produce nitrite ( ) toxicity. It has been reported that rumen protozoa have greater ability for and reduction than bacteria. It was hypothesised that the absence of ruminal protozoa in sheep may lead to higher accumulation in the rumen and a higher blood methaemoglobin (MetHb) concentration.

View Article and Find Full Text PDF

Nitrate (NO ) is an effective non-protein nitrogen source for gut microbes and reduces enteric methane (CH ) production in ruminants. Nitrate is reduced to ammonia by rumen bacteria with nitrite (NO ) produced as an intermediate. The absorption of NO can cause methaemoglobinaemia in ruminants.

View Article and Find Full Text PDF

This experiment was to evaluate a suite of biological traits likely to be associated with genetic variation in residual feed intake (RFI) in Angus cattle. Twenty nine steers and 30 heifers bred to be divergent in postweaning RFI (RFIp) and that differed in midparent RFIp-EBV (RFIp-EBVmp) by more than 2 kg DMI/d were used in this study. A 1-unit (1 kg DM/d) decrease in RFIp-EBVmp was accompanied by a 0.

View Article and Find Full Text PDF