The Impact of Overstocking and Negative Energy Balance on Quantitative Measurement of Non-typhoidal Salmonella in Periparturient Dairy Cattle.

Stressful conditions in animal production facilities may exacerbate the fecal shedding and foodborne transmission of non-typhoidal Salmonella enterica subsp. enterica. Dairy cows are reservoirs of this zoonotic microorganism, and its prevalence has roughly doubled in the past decade on dairy farms in United States. Dairy cows are commonly overstocked at the feed bunk, and stressors placed on the animal prior to parturition may exacerbate Salmonella shedding. However, no studies have evaluated the impact of overstocking and metabolic stress on fecal concentrations of the pathogen. Therefore, we conducted a field trial with 120 multiparous dairy cows randomized into one of four treatment groups with different stocking densities at the feed bunk during the periparturient period as follows: US, understocked from -60 to -1 DRC; OS, overstocked from -60 to -1 DRC; USOS, understocked from -60 to -26 DRC/overstocked from -25 to -1 DRC; and OSUS, overstocked from -60 to -26 DRC/ understocked from -25 to -1 DRC. Fecal and blood samples were collected at four time points relative to calving. qPCR assays were used to quantify Salmonella invA gene and total bacterial community from fecal samples, and a subset of isolates recovered from fecal bacterial culture were characterized using pulsed field gel electrophoresis and serotyping. Serum non-esterified fatty acids (NEFA) were measured as a metabolic stress indicator using an immunoassay. Multivariable analyses were performed to test if changes in Salmonella concentrations were associated with stocking density, energy balance, or days relative to calving. From fecal isolates, three Salmonella serovars were identified, S. Cerro; Kentucky; Meleagridis. Concentrations of Salmonella increased as cows approached calving. Higher stocking densities at the feed bunk did not impact total bacterial community or NEFA; however, cows in the overstocked groups had higher Salmonella fecal concentrations. Further, cows with higher NEFA concentrations after calving had a higher likelihood of detection of Salmonella. Future farm interventions should aim to reduce environmental and metabolic stress during the periparturient period to decrease the dissemination of Salmonella to cattle, the environment, and humans.

Milk yield and composition from ewes fed diets containing narasin and their lambs' performance.

The changes promoted by feed additives in ruminal fermentation, especially increasing the availability of propionate, can improve the energy balance of an animal, which is of great importance in the lactation period. This trial aimed to evaluate the inclusion of narasin in the diet of lactating ewes on milk yield, composition, dry matter intake (DMI), and plasma metabolites of the ewes and growth rate of lambs. Thirty-two lactating ewes (59.0 ± 2.42 kg) were assigned to a randomized complete block design. The experimental diets contained 500 g/kg of dry matter (DM) of coast cross (Cynodon dactylon (L.) Pers) hay and 500 g/kg DM of concentrate, and the treatments were: N0-no narasin inclusion; N13-inclusion of 13 mg of narasin/kg DM. Once a week, from week 2 to 10 of lactation, ewes were separated from their lambs, injected with oxytocin, and milked mechanically to empty the udder. After 3 h, the milk production was recorded, using the same procedure, and sampled to evaluate the composition. The blood samples were taken weekly, 4 h after feeding. The average daily gain (ADG) and starter DMI of the lambs were evaluated weekly from week 2 to 12 of age. The inclusion of narasin did not affect (P = 0.93) DMI of ewes; however, it increased milk production (P < 0.01) and feed efficiency (P = 0.02; FE). Ewes fed N13 had a greater milk fat (P < 0.01), protein (P < 0.01), lactose (P = 0.04), and total solids production (P < 0.01). Narasin inclusion in ewe's diet increased plasma glucose concentration (P = 0.05) at weeks 8, 9 and 10; however, there was no effect on plasma urea concentration (P = 0.96). The lambs of N0 ewes had a greater starter DMI (P < 0.01) at weeks 7, 8, 9, and 10; however, the ADG and body weight at weaning and after weaning were similar between treatments (P > 0.05). The results showed that the inclusion of 13 mg of narasin/kg DM improved the milk production and FE of the ewes without altering the composition of the milk. The lower initial consumption of concentrate by N13 lambs before weaning was caused by the higher production of milk. The results obtained in the present study demonstrate the possible productive gain with the inclusion of narasin in diets for lactating ewes.

Bovine adipose triglyceride lipase is not altered and adipocyte fatty acid-binding protein is increased by dietary flaxseed.

In this paper, we report the full-length coding sequence of bovine ATGL cDNA and analyze its expression in bovine tissues. Similar to human, mouse, and pig ATGL sequences, bovine ATGL has a highly conserved patatin domain that is necessary for lipolytic function in mice and humans. This suggests that ATGL is functionally intact as a triglyceride lipase in cattle. Tissue distribution of ATGL gene expression was highest in fat and muscle (skeletal and cardiac) tissue, while protein expression was solely detectible in the adipose tissue. The effect of 109 days of flaxseed supplementation on ATGL and adipocyte fatty acid-binding protein (FABP4 or A-FABP, E-FABP or FABP5) expression was examined in Angus steers. Supplemented steers had greater triacylglycerol (TAG) content in the muscle compared with unsupplemented ones. Additionally, supplementation increased A-FABP expression and decreased stearoyl-CoA desaturase 1 (SCD-1) expression in muscle, while total ATGL expression was unaffected. In summary, supplementation of cattle rations with flaxseed increased muscle TAG concentrations attributed in part to increased expression of key enzymes involved in lipid trafficking (A-FABP) and metabolism (SCD-1).