Smallholder large ruminant production in Lao People’s Democratic Republic (Laos) is characterised by low reproductive efficiency. To determine if common abortifacient bovid infectious diseases are involved, a serological investigation was conducted. Sera was collected from stored and fresh cattle (n = 390) and buffalo (n = 130) samples from 2016–18 from, and then examined for associations in a retrospective risk factor study of 71 herds. The sera were assayed for antibodies to Neospora caninum, bovine viral diarrhoea virus (BVDV), Leptospira interrogans serovar Hardjo and Brucella abortus using commercially available enzyme-linked immunosorbent assay kits. These pathogens were detected in buffalo samples at 78.5% (95% CI 71.4–85.6), 0%, 2.3% (95% CI 0–4.9) and 0%, respectively, and in cattle at 4.4% (95% CI 2.4–6.4), 7.7% (95% CI 3.1–12.3), 12.8% (95% CI 9.5–16.1) and 0.26% (95% CI 0–0.8), respectively. Exposure of buffalo to N. caninum was positively associated with buffalo age, with a predicted seropositivity at birth of 52.8%, increasing to 97.2% by 12 years of age (p = 0.037). Exposure of cattle to L. interrogans serovar Hardjo was more prevalent in females compared to males, was associated with higher titres of BVDV, and was more prevalent in the wet season compared to the dry season. Exposure of cattle to BVDV was more prevalent in males compared to females, the wet and dry seasons were comparable, and was associated with rising antibody titres against N. caninum and L. interrogans serovar Hardjo. The risk factor survey identified that the probability of herds being N. caninum positive increased with farmer age, if farmers believed there were rodents on farm, and if farmers weren’t aware that canids or rodents could contaminate bovid feed on their farm. The probability of a herd being positive to L. interrogans serovar Hardjo increased on farms where multiple cows shared the same bull, where farmers had lower husbandry knowledge, and on farms that used water troughs. The probability of a herd being BVDV seropositive increased with increasing herd size and increasing titres to N. caninum. The benchmarking of bovid exposure to emerging abortifacient pathogens and identification of their risk factors potentially informs disease prevention strategies, supporting efforts to establish a biosecure beef supply for enhanced smallholder livestock productivity, public health and food security in Laos and surrounding countries.

Context: Anthelmintic treatments are not widely adopted by smallholder farmers in Laos (Lao People’s Democratic Republic) to treat bovid Toxocara vitulorum, resulting in high calf morbidity and mortality. Aims: Field trials were conducted to provide baseline efficacy data on an alternative, easy-to-use treatment by provision of fenbendazole-medicated molasses blocks (FMB) in situ. Methods: Participating villages were randomly allocated to the following treatments: (1) conventional orally administered pyrantel, (2) access to FMB, (3) access to non-medicated molasses blocks (MB), and (4) no blocks (control). Faecal eggs per gram (EPG) and weight were monitored in cattle (n = 171) and buffalo calves (n = 44) under field conditions for 48–56 days. Key results: In 2016, the MB treatment was associated with the fastest reduction in predicted average EPG at 2% per day, while FMB and pyrantel had an equivalent reduction of 1% per day, relative to the control (P = 0.062). Predicted average weight also differed significantly among treatments, with pyrantel and MB having the greatest average daily gain at 230 g and FMB at 200 g, which was higher than for control calves at 170 g (P = 0.002). In buffalo calves, treatment was not significantly associated with EPG or weight. The 2018 trial corroborated that FMB and MB treatments were associated with increased EPG reductions in cattle at 3% per day, relative to control calves (P = 0.007). Again, the MB treatment had the greatest predicted average daily gain at 200 g, compared with FMB calves at 160 g and control calves at 150 g (P = 0.005). Conclusions: The field trials provided baseline evidence that FMB and MB have potential applications in reducing environmental contamination of T. vitulorum eggs and may improve calf growth in low-input systems. However, further testing ex situ is required to control for variability in calf weight and T. vitulorum burdens, so as to optimise anthelmintic doses, assess the addition of urea to the block formula and assess product marketability. Implications: If successful, medicated nutrient blocks may be a simple method to reduce calf mortality and morbidity, enhancing the reproductive efficiency of large ruminant production in smallholder farms in developing countries.

Due to the large and growing quantity of microplastics being generated, their ubiquity in agricultural landscapes, their likelihood of being ingested by livestock and poultry, and their potential impacts on performance and meat products, microplastics are a potential risk to livestock and poultry production. Here, we reviewed the literature for microplastic effects on ruminant, pig and poultry health, productivity, and meat products. It was observed that controlled experimental studies show that microplastics have localised effects on livestock and poultry health, as indicated by oxidative stress, inflammation and apoptosis, following short-term exposure to concentrations higher than is environmentally typical. However, it is unclear if microplastics have gross effects on disease, productivity and welfare at natural exposure levels. Microplastics are present in livestock and poultry tissues at levels that make it a potential consumer safety issue (0–7700 mg per kg or 100–180,000 particles per kg). However, the detection methods used are prone to contamination, meaning that true concentrations remain unknown, as does the source of microplastics in terms of whether they originate from production or meat processing and packaging. Microplastics have been detected in the livestock and poultry environment, with 36–300 particles detected per kg livestock feed and 0.34–7900 particles detected per kg soil. Livestock ingest microplastics from their environments, as evidenced by microplastics being detected in chicken excreta at 667–129,800 particles per kg, in ruminant faeces at 74–50,583 particles per kg, and in pig faeces at 0–112,000 particles per kg. However, preliminary data have neither examined correlations to animal productivity, nor have they estimated the total amount and type of microplastics to which livestock and poultry are exposed. This information is needed to inform the doses used in controlled experiments aiming to understand the effect of natural exposure levels on health, productivity and meat quality. To accurately estimate microplastics in livestock supply chains, there is a need to optimise and standardise microplastic detection methods by including procedural blanks, and calculating limits of detection, recovery rate of sample digestion, sample size calculations, and reports of microplastic size, density, weight and number of particles detected. No study has investigated the sources of microplastics and effective mitigation measures in livestock supply chains. Preliminary data also show that microplastics are vectors for heavy metals, antibiotics, antibiotic resistance genes and microbes. Further research is strongly warranted to quantify the effects of microplastics as vectors. In conclusion, microplastics are present in livestock and poultry production systems, and this poses a threat to animal welfare, productivity and consumer perceptions of meat. This review has highlighted paucities in current knowledge that must be addressed to understand the scope of microplastic effects on the livestock and poultry industries, as well as the opportunities for risk mitigation.

Context: Large-ruminant production in developing countries is inefficient with low growth rates and declining weights, particularly in the dry season. Aims: The impact of ad libitum supplementation of cattle with high-quality molasses blocks (20 kg) containing either 8% urea (UMB) or nil urea (MB), was examined. Methods: Field trials on smallholder farms compared weight changes and average daily gains (ADG = g/day) data of young calves <8 months of age (n = 25); growing calves 8–24 months (n = 35) and lactating cows (n = 46), of the indigenous breed when accessing either UMB or MB, with data being collected at Weeks 1, 4, 8 and 12. A pen study was also conducted at a research station involving mature, lactating crossbred cows (n = 37). Surveys of farming families experiencing use of the blocks was conducted (n = 20). Key results: On smallholder farms, animals accessing UMBs were heavier than those accessing MBs at every collection day and in young calves these differences were statistically significant (P < 0.05). ADGs were higher in cattle accessing UMB than in those accessing MBs. Young calves had the highest ADG (251–265 g/day), followed by growing calves (198–237 g/day) and lactating cows (187–190 g/day), although differences in ADG between UMB and MB cohorts were not considered significant (young calves P = 0.562; growing calves P = 0.509; and lactating cows P = 0.993). Results from the pen study identified that ADGs were not significantly different (P = 0.933) between crossbred cows accessing MBs (236 g/day) and cows accessing UMBs (229 g/day). Surveys of farmers using blocks confirmed that their animals were calmer and healthier, and had better coat condition with minimal external parasites; these farmers wished to purchase the blocks and were willing to pay a mean up to US$6.5 ± 2.3 per block. Conclusions: Provision of UMBs and MBs in Laos in the late dry season improved cattle growth rates, which is consistent with previous studies and far superior to the base-line data from Laos demonstrating declining ADGs. Farmers considered that the blocks contributed greatly to herd management and improved sale-ability of their cattle. Implications: Provision of molasses blocks on low-input smallholder farms in developing countries significantly improves production efficiency, offering an ‘entry point’ intervention while forages are becoming established.