The present study aimed to evaluate the effect of crude protein degradability and corn processing on lactation performance, milk protein composition, milk ethanol stability (MES), heat coagulation time (HCT) at 140 degrees C, and the efficiency of N utilization for dairy cows. Twenty Holstein cows with an average of 162 +/- 70 d in milk, 666 +/- 7 kg of body weight, and 36 +/- 7.8 kg/d of milk yield (MY) were distributed in a Latin square design with 5 contemporaneous balanced squares, 4 periods of 21 d, and 4 treatments (factorial arrangement 2 x 2). Treatment factor 1 was corn processing [ground (GC) or steam-flaked corn (SFC)] and factor 2 was crude protein (CP) degradability (high = 10.7% rumen-degradable protein and 5.1% rumen-undegradable protein; low = 9.5% rumen-degradable protein and 6.3% rumen-undegradable protein; dry matter basis). A significant interaction was observed between CP degradability and corn processing on dry matter intake (DMI). When cows were fed GC with low CP degradability, DMI increased by 1.24 kg/d compared with cows fed GC with high CP degradability; however, CP degradability did not change DMI when cows were fed SFC. Similar interactions were observed for MY, HCT, and lactose content. When cows were fed GC diets, high CP degradability reduced MY by 2.3 kg/d, as well as HCT and lactose content, compared with low CP degradability. However, no effect of CP degradability was observed on those variables when cows were fed SFC diets. The SFC diets increased dry matter and starch total-tract digestibility and reduced beta-casein (CN) content (% total milk protein) compared with GC diets. Cows fed low-CP degradability diets had higher glycosylated kappa-CN content (% total kappa-CN) and MES, as well as milk protein content, 3.5% fat-corrected milk, and efficiency of N for milk production, than cows fed high-CP degradability diets. Therefore, GC and high-CP degradability diets reduced milk production and protein stability. Overall, low CP degradability increased the efficiency of dietary N utilization and MES, probably due to changes in casein micelle composition, as CP degradability or corn processing did not change the milk concentration of ionic calcium. The GC diets increased beta-CN content, which could contribute to reducing HTC when cows were fed GC and high-CP degradability diets.

Bacillus cereus is a spore-forming, Gram-positive bacterium that causes foodborne illness and dairy spoilage. This study analyzed B. cereus s.s. isolates from milking environments, raw milk, and dairy products to assess their genotypic and phenotypic traits. From 466 samples, 61 isolates were obtained: 27 from milking environments, 9 from dairy environments, 8 from raw milk, and 17 from dairy products. Genomic sequencing identified genes encoding proteolytic (BC5350, BC0666, BC2984, BC0598, BC5351, BC3383, BC2735), lipolytic (BC4862, BC2141, BC1027, BC4123, BC4345, BC5402, BC5401), and esterase (BC1954, BC4515, BC3413, BC3606) enzymes. Plate assays confirmed enzymatic activities. Proteolytic genes were more prevalent in environmental samples, followed by raw milk and dairy products. Lipolytic genes were most frequent in raw milk, followed by environmental samples and dairy products. Esterase genes were most common in dairy environments. These findings suggest that dairy processing influences the enzymatic profile of B. cereus s.s., potentially impacting food safety and quality in the dairy industry. Understanding the distribution of these genes may help develop strategies to mitigate spoilage and contamination risks in dairy products.

Summary: Information on milk production and composition was obtained from 1,786 lactating cows in a Brazilian commercial herd, for which data provided by the dairy farm in Brazil were adopted as selection criteria, such as genotypes for the β-casein gene extracted from the Clarifide Zoetis software, days in milk, and number of lactations. Thus, 18 cows were selected, analyzing the association between the genotype for the β-casein CSN2 gene and milk production and composition characteristics and energy, enzymatic, and nitrogen metabolites of blood, milk, and urine. No association between β-casein gene polymorphism and any of the variables under study was observed.

The pre-chilling of rabbit carcasses in an immersion tank directly interferes with microbial control. Therefore, this study was developed to examine the influence of different pre-chill tank water temperatures (4, 7, and 10 °C) on the microbiological quality of rabbit carcasses. Samples of rabbit carcasses and water and ice from the pre-chiller tank were collected; mesophilic aerobic heterotrophic microorganisms (MES), enterobacteria (EC), and coagulase-positive Staphylococcus (CPS) were counted; and the presence of Salmonella spp. was investigated. After the carcasses were immersed in the pre-chiller, there was a significant increase (p < 0.05) in MES (38.69 and 88.06 Log CFU·mL⁻¹ at 4 and 10 °C, respectively) and EC (3.20, 4.15, and 4.84 Log CFU·mL⁻¹ at 4, 7, and 10 °C, respectively). The average EC count tended to increase after the carcasses were immersed in the pre-chiller at different temperatures, but this increase was not significant. Water samples showed MES, EC, and CPS counts only after the immersion of the carcasses; however, the presence of these microorganisms was not detected in any of the ice samples. Salmonella spp. was not identified in the analyzed samples. The microorganisms analyzed at the three pre-chiller water temperatures evaluated did not multiply on the surface of the rabbit carcasses or in the pre-chiller water after carcass immersion. This study showed that none of the three pre-chilling temperatures were able to reduce the count of indicator microorganisms in the carcasses of rabbits. These data provide scientific support to discuss the need for specific norms and guidelines for rabbit meat production.

This study investigated how corn processing and protein degradability affect ruminal fermentation and feeding behavior in lactating Holstein cows. Twenty cows (averaging 162 ± 70 days in lactation, 666 ± 7 kg body weight, and 36.0 ± 7.8 kg/day milk yield) were assigned in a Latin square design with four 21-day periods and four treatments arranged in a 2 × 2 factorial: corn processing [ground corn (GC) vs. steam-flaked corn (SFC)] and crude protein (CP) degradability [high (HCP) vs. low (LCP)]. Ruminal samples were collected at eight time points (0, 2, 4, 6, 8, 10, 12 and 16 h) post-feeding to analyze pH, ammonia, and short-chain fatty acids, while feeding behavior was recorded visually every 5 min for 48 h. Corn processing and protein degradability interacted to influence rumen ammonia nitrogen (p = 0.057), urinary pH, (p = 0.041), nitrogen secretion and efficiency (p = 0.538), and feeding (min/kg DM; p = 0.049) and rumination times (min/kg DM, p = 0.001; min/kg NDF, p = 0.001), reflecting changes in nitrogen metabolism. Steam-flaked corn decreased the acetate/propionate ratio and enhanced propionate production, improving nitrogen retention and reducing urinary N losses, while highly degradable protein increased ruminal NH₃-N and branched-chain VFA concentrations, particularly when combined with ground corn. Additionally, steam flaking reduced feed selectivity and increased rumination efficiency, supporting more effective use of nutrients for milk N secretion and overall nitrogen utilization efficiency in dairy cows. Overall, diets varying in corn processing and protein degradability altered ruminal metabolism, nutrient utilization, feeding behavior, and diet selectivity in lactating cows, highlighting their importance in optimizing dairy cow performance.