Disease control reduces greenhouse gas emissions
There is considerable evidence that improving productivity reduces environmental impacts from livestock production. However, despite the negative impacts of animal diseases on reproduction, growth and milk production, there is little information available on the impacts of animal disease on greenhouse gas emissions (GHGe). This study by Capper (2023) (10.1186/s42522-023-00089-y) aimed to partially address this knowledge gap by investigating the effects of globally important vaccine-preventable diseases on GHGe from various livestock systems, namely: intensive dairy, extensive beef, commercial swine and backyard poultry. Simple deterministic models were developed to quantify the impacts of livestock disease on productivity (defined as total milk and/or meat yield, MMY) adjusted for disease prevalence both at the population level (high or low) and at the herd or flock level. Disease-induced changes in MMY were applied to the GHGe per kg of milk or meat according to the consequent changes in live-stock populations required to maintain milk or meat production. Diseases investigated comprised foot and mouth, brucellosis, anthrax, lumpy skin disease, classical swine fever, porcine reproductive and respiratory syndrome, low and high pathogenicity avian influenza, avian infectious bronchitis and Newcastle disease. All diseases investigated had multifactorial impacts on total MMY, yet diseases that increased mortality in breeding or growing livestock (eg anthrax, classical swine fever and high pathogenicity avian influenza) showed greater impacts on GHGe per unit of milk or meat produced than those that primarily affect yields or reproduction (eg brucellosis or low pathogenicity avian influenza). Prevalence also had considerable effects on potential GHGe. Effective reduction of the prevalence of porcine reproductive and respiratory syndrome from 60 to 10%, foot and mouth in beef cattle from 45 to 5%, or avian infectious bronchitis in poultry from 75 to 20% would reduce GHGe by 22.5%, 9.11% and 11.3% respectively. Controlling livestock disease can reduce MMY losses at the farm level, which improves food security, reduces GHGe and enhances livestock system sustainability.
Effect of vaccination on performance and antimicrobial use
A study by Santinello et al (2024) (10.1016/j.prevetmed.2024.106130) aimed to investigate how the timing of first bovine respiratory disease (BRD) vaccination and the different vaccination target pathogens affect antimicrobial use (AMU) and performance of young beef cattle imported from France to Italy. Information on animal performance, antimicrobial treatments, and vaccinations was available for 60 726 Charolais cattle belonging to 1449 batches in 33 Italian specialised fattening farms between January 2016 and December 2021. Antimicrobial use was estimated using the treatment incidence 100 adapted for Italy (TI100it). A mixed linear model was used to quantify the effects of the vaccination and the time of first administration on slaughter age, carcase weight and average daily carcase gain. Similarly, a generalised linear mixed model was used to analyse the TI100it. The vaccination programme was usually applied the first day after the animals' arrival at the Italian farms. Most animals were vaccinated with a polyvalent vaccine against infectious bovine rhinotracheitis, bovine parainfluenza type 3 virus (PI-3), bovine viral diarrhoea virus type 1 and 2 (BVDV), and bovine respiratory syncytial virus (BRSV). The most used class of antimicrobials to treat BRD were the macrolides. Animals that got vaccinated against any of the considered BRD pathogens upon arrival had significantly lower TI100it, greater average daily carcase gain, and reached slaughter age earlier than animals vaccinated later. Animals that received the vaccination against BVDV had lower TI100it and greater average daily carcase gain, and animals that received the vaccination against BRSV were younger at slaughter than unvaccinated animals. The vaccination against Mannheimia haemolytica significantly decreased the slaughter age and increased the carcase weight and average daily carcase gain. However, vaccination against PI-3 and Histophilus somni significantly increased the slaughter age. This study tends to further support the sustainability benefits of disease control via vaccination, but the authors conclude it would be better to vaccinate the cattle before they leave their farm of origin.
Methane emissions
Data on the enteric methane emissions of individual cows are useful as inputs for animal genetic evaluations. Data generation for many animal characteristics, including enteric methane emissions, can be expensive and time consuming, so being able to extract as much information as possible from available samples or data sources is worthy of investigation. The objective of a study by McParland et al (2024) (10.3168/jds.2023-23577) was to attempt to predict individual cow methane emissions from the information contained within milk samples, specifically the spectrum of light transmittance across different wavelengths of the mid-infrared (MIR) region of the electromagnetic spectrum. A total of 93 888 individual spot measures of methane (ie, individual samples of an animal's breath when using the GreenFeed technology) from 384 lactations on 277 grazing dairy cows were used in the analysis. Results suggest that enteric methane can be reasonably well predicted from the infrared spectrum of milk samples. What is yet to be established, however, is whether (a) genetic variation exists in this predicted enteric methane phenotype and (b) selection on estimates of genetic merit for this phenotype translate to actual phenotypic differences in enteric methane emissions.