Specific and non-specific effects of Mycobacterium bovis BCG vaccination in dairy calves.

Bovine tuberculosis (bTB) is a chronic disease mainly caused by Mycobacterium bovis, a zoonotic pathogen with economic significance as it leads to reduced milk and meat production, and high costs for control measures. The Bacillus Calmette-Guérin (BCG) vaccine, primarily used to prevent tuberculosis in humans, has also been studied for controlling bTB. While showing effectiveness in preventing M. bovis infection and disease in cattle, the BCG vaccine can induce non-specific effects on the immune system, enhancing responses to infections caused by unrelated pathogens, and also having non-specific effects on lactation. The aim of this study is to describe both the specific and non-specific effects of BCG vaccination in calves from a commercial dairy herd in central Chile. Diagnosis of M. bovis infection was performed through the IFNγ release assay (IGRA) using ESAT6/CFP-10 and Rv3615c antigens. The records of milk production, somatic cell count (SCC), clinical mastitis (CM) and retained placenta (RP) during the first lactation were compared between vaccinated and non-vaccinated animals. The breed (Holstein Friesian [HF] v/s HF × Swedish Red crossbred [HFSR]) and the season (warm v/s cold) were also analyzed as categorical explanatory variables. Results of IGRA showed significant differences between vaccinated and control groups, indicating a vaccine efficacy of 58.5% at 18 months post vaccination in HFSR crossbred animals. Although milk production did not vary, SCC and CM showed differences between groups, associated to the breed and the season, respectively. When analyzing CM and RP as a whole entity of disease, BCG showed protection in all but the cold season variables. Overall, the BCG vaccine induced protective specific and non-specific effects on health parameters, which may be influenced by the breed of animals and the season. These results provide new features of BCG protection, supporting initiatives for its implementation as a complementary tool in bTB control.

Comparison between linseed expeller and canola expeller on concentrate intake, and circulating inflammatory mediators in Holstein calves.

The objective of this study was to compare the effect of linseed and canola expeller on average daily weight gain (ADG), concentrate intakes, incidence of diarrhea, serum haptoglobin, interleukin (IL)-1, and resolvin-E1 in female Holstein calves from birth to weaning. A sample size of 20 calves per group was calculated and were randomly allocated at the time of birth. Linseed group (LIN) was fed a starter with linseed expeller, while canola group (CAN) received a similar concentrate, but with canola expeller. Both expellers were included at a rate of 25% dry matter (DM) basis of the starter. Pasteurized waste milk was fed twice a day until weaning. Calves were weighed at birth, 30, and 60 d of age. Starter intake was evaluated daily from 5 to 60 d. A blood sample was obtained at birth, 14, 28, 35, and 49 d of age, and bovine serum resolvin-E1, haptoglobin, and IL-1 were assayed by commercial enzyme-linked immunosorbent assay (ELISA) kits. Incidence of diarrhea and the duration of the events were also recorded. The effect of the interaction group by time on body weight (BW) and starter intake was not significant (P > 0.05). Average daily gains (ADG) from 0 to 60 d for CAN and LIN groups were 0.680 and 0.675 kg/d (P > 0.05), respectively. Incidences of diarrhea were 25% and 45% for CAN and LIN groups, respectively (P = 0.18). LIN group had greater concentrations of IL-1 at d 21, haptoglobin at d 7, and resolving-E1 at d 14 and 49 than CAN group, respectively. It is concluded that BW at weaning, ADG, and concentrate intakes were not different between groups fed starters containing linseed or canola expeller (25% inclusion). The concentrations of cytokines and haptoglobin were the greatest in LIN group.

The association between serum ß-hydroxybutyrate and milk fatty acid profile with special emphasis on conjugated linoleic acid in postpartum Holstein cows.

BACKGROUND: Ketogenesis is a secondary metabolic pathway to provide energy to dairy cows during early lactation; however when the production of ketone bodies (acetoacetate, acetone, ß- hydroxybutyrate) is above certain levels a subclinical disorder may appear. The aim of the present study was to investigate the association between serum concentrations of ß- hydroxybutyrate (BHBA) and fatty acid (FA) profile of milk with emphasis in conjugated linoleic acid (CLA) in a population of early lactation Holstein cows. Fifty cows between parity 1 and 5, ranging from 14 to 21 days in milk, were randomly selected from 3 farms of the central area of Chile for determination of serum BHBA concentrations, milk fat content, and milk FA profiles. RESULTS: Cows were divided in low (n = 26) and high (n = 24) BHBA groups considering the median value of the serum concentration of BHBA (0.7 mmol/L) (SEM = 0.094). Mean milk fat % was 3.45% and 3.60% for cows in the low and high BHBA groups, respectively (P = 0.15). Concentrations of several FA were significantly different between both groups. Specifically, mean CLA concentrations were 0.40% (4 ± 0.03 g/kg) and 0.33% (3.3 ± 0.03 g/kg) for the low and high BHBA groups, respectively (P = 0.05). CONCLUSIONS: It is concluded that early postpartum cows with serum BHBA > 0.7 mmol/L tended to have higher milk fat % and had significantly lower concentrations of CLA than early postpartum cows with BHBA ≤ 0.7 mmol/L.

Endometrial expression of selected transcripts in postpartum of primiparous Holstein cows with clinical and subclinical endometritis.

Postpartum endometritis compromises milk production and fertility in high-producing dairy cows. Infection of the endometrium induces an inflammatory response with secretion of cytokines that lead to polymorphonuclear cells (PMN) influx and bacterial clearance. Considering that only a portion of cows with endometritis is eligible for clinical diagnosis, there is an increasing effort for developing reliable tools and protocols for diagnosis of subclinical endometritis. Recent reports have indicated that primiparous cows are at greater risk of uterine infection and primiparous cows with subclinical endometritis produce less milk compared to healthy cows. In the present study, gene expression profiles were compared for selected cytokine and hormone endometrial transcripts in the postpartum of primiparous Holstein cows with clinical and subclinical endometritis. Cows were classified as healthy (no signs of clinical endometritis), cows with subclinical endometritis (PMN<5% in the cytological sample) and cows with clinical endometritis (PMN>5%). Although, cows with clinical endometritis had greater (P<0.05) relative amounts of mRNA for the IL1A, IL6, IL17A, TNFα, PGES and PGHS2 genes compared to healthy cows; no significant differences were detected between clinical and subclinical endometritis groups. Spearman correlation coefficients were positive between relative amounts of gene expression as indicated by amount of these transcripts and PMN percentages and ranged from 0.74 to 0.93 (P<0.05). Relative amounts of cytokine mRNA suggest similar inflammatory response in the endometrium of cows with subclinical and clinical endometritis. Moreover, differential relative amounts of hormone transcripts suggest dysregulation of the luteolytic mechanism and PG synthases but not ERα in cows with endometritis.