Addition of Bacillus sp. inoculums in bedding for swine on a pilot scale: effect on microbial population and bedding temperature

Full-Scale Composting of Different Mixtures with Meal from Dead Pigs: Process Monitoring, Compost Quality and Toxicity

ABSTRACT

Abundant by-products of large swine industries, such as slaughterhouse sludge and carcasses, require adequate treatment to prevent negative effects of their direct disposal in the open environment. This study is aimed to evaluate the efficiency of composting using meal from dead pigs through physicochemical analyses and phytotoxic assays. Five treatments were tested, all including 50% sawdust: T1, with 50% slaughterhouse sludge (control); T2, with 20% slaughterhouse sludge and 30% meal from dead pigs; T3, with 10% slaughterhouse sludge and 40% meal from dead pigs; T4, with 20% organic stabilizing compost and 30% meal from dead pigs and T5, with 30% organic stabilizing compost and 20% meal from dead pigs. The phytotoxicity assays used lettuce, cucumber, celia, soybean, rice and wheat as bioindicators. Inclusion of meal from dead pigs was related to reduction in pH, C/N ratio, humidity and temperatures inside the pile, although thermophilic peaks lasted longer than 50 days and the final composts showed high content of nitrogen and phosphorous. The germination of bioindicators was reduced in all tested treatments, compared to the control. The composts from treatments that included meal from dead pigs presented acceptable nutrient content, which may indicate their use as organic fertilizers. However, after 4 months, all bioindicators in contact with such composts presented impaired germination.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12649-021-01422-0.

Cross-sectional study of the relationships among bedding materials, bedding bacteria counts, and intramammary infection in late-lactation dairy cows

Objectives of this study were to (1) describe the intramammary infection (IMI) prevalence and pathogen profiles in quarters of cows approaching dry-off in US dairy herds, (2) compare IMI prevalence in quarters of cows exposed to different bedding material types, and (3) identify associations between bedding bacteria count and IMI in cows approaching dry-off. Eighty herds using 1 of 4 common bedding materials (manure solids, organic non-manure, new sand, and recycled sand) were recruited in a multi-site cross-sectional study. Each herd was visited twice for sampling. At each visit, aseptic quarter-milk samples were collected from 20 cows approaching dry-off (>180 d pregnant). Samples of unused and used bedding were also collected. Aerobic culture was used to determine the IMI status of 10,448 quarters and to enumerate counts (log₁₀ cfu/mL) of all bacteria, Staphylococcus spp., Streptococcus spp. and Streptococcus-like organisms (SSLO), coliforms, Klebsiella spp., noncoliform gram-negatives, Bacillus spp., and Prototheca spp. in unused (n = 148) and used (n = 150) bedding. The association between bedding bacteria count and IMI was determined using multivariable logistic regression with mixed effects. Quarter-level prevalence of IMI was 21.1%, which was primarily caused by non-aureus Staphylococcus spp. (11.4%) and SSLO (5.6%). Only modest differences in IMI prevalence were observed between the 4 common bedding material types. Counts of all bacteria in unused bedding was positively associated with odds of IMI caused by any pathogen [ALL-IMI; odds ratio (OR) = 1.08]. A positive association was also observed for counts of SSLO in unused bedding and SSLO-IMI (OR = 1.09). These patterns of association were generally consistent across the 4 common bedding materials. In contrast, the association between counts of all bacteria in used bedding and ALL-IMI varied by bedding type, with positive associations observed in quarters exposed to manure solids (OR = 2.29) and organic non-manure (OR = 1.51) and a negative association in quarters exposed to new sand (OR = 0.47). Findings from this study suggest that quarter-level IMI prevalence in late-lactation cows is low in US dairy herds. Furthermore, bedding material type may not be an important risk factor for IMI in late lactation. Higher levels of bacteria in bedding may increase IMI prevalence at dry-off in general, but this relationship is likely to vary according to bedding material type.