Effects of Receiving Two Initial Feedings of Colostrum on the Average Daily Gain and Health of Pre-Weaning Group Housed Holstein Heifer Calves.

We studied the effect on average daily gain (ADG) and health of an additional colostrum feeding to Holstein dairy heifers 12-16 h after the first colostrum feeding, provided within 2 h of birth. Calves (n = 190) with an average birth weight of 38.8 kg (29.5-52.6 kg) were randomly enrolled in blocks to either the control (CON) or colostrum (COL). The CON received 3 L of acidified pasteurized whole milk, and the COL received 3 L of pasteurized colostrum [average: 25.5 (24.7-26.4)% Brix]. Calves were group-housed, weighed, withers height measured weekly. Serum was obtained and analyzed with a% Brix refractometer. Mixed linear models were used to assess the differences in ADG, body weight, and height between the treatment and control. There was no difference in ADG between the COL and CON. However, serum % Brix was higher in the COL group (9.7%) than in the CON group (9.2%). Calves in the COL had more antibiotic treatments for respiratory diseases but fewer antibiotic treatments for otitis than the CON. In conclusion, providing an extra feeding of colostrum did not contribute to ADG of Holstein heifers during the pre-weaning period but did provide them with a higher total serum protein concentration.

Blood ß-hydroxybutyrate concentrations and early lactation management strategies on pasture-based dairy farms in Colombia.

The increasing global demand for food requires sustainable solutions to close the gap in agricultural yield between industrialized and non-industrialized countries. Our objectives in this cross-sectional study were to: 1) characterize farm populations, milk yield, and early lactation management strategies of dairy cows in three different regions of Colombia, and 2) determine the association of these management strategies with blood ß-hydroxybutyrate (BHB) concentrations in the first 42 days in milk (DIM). Dairy herds (n = 56) in the Antioquia, Caldas, and Cundinamarca regions of Colombia were visited once from May through July 2018. A survey was administered to farm owners to collect demographic, management, and herd nutrition information. Blood samples from dairy cows (n = 880) between calving and 42 DIM were used to measure blood BHB concentration. Associations between management and nutritional strategies and blood BHB concentration were examined using mixed models. Prevalence of hyperketonemia was calculated as the number of samples with BHB concentration ≥1.2 mmol/L divided by the total number of samples. The estimated diet composition for early lactation dairy cows was 65.5% pasture and 31.8% commercial concentrates. The farm median milk yield, protein concentration, and fat concentration were 21.0 kg (range = 13.1-36 kg), 3.2% (range = 2.7-4.1%), and 3.5% (range = 3.0-4.1%), respectively. Milk yield least squares means (95% confidence interval; CI) differed by region: 21.7 (20.3, 23.2), 18.5 (17.0, 20.2), and 20.3 (18.5, 22.4) kg in Antioquia, Caldas, and Cundinamarca, respectively. Median blood BHB concentration was 0.5 and ranged from 0.1-4.4 mmol/L; blood BHB concentration was not different among the three regions. Pasture fertilization, increased parity, and BCS were associated with changes in blood BHB concentration. The overall prevalence of hyperketonemia was 4.5%. Geographical region affected the prevalence of hyperketonemia at 2.5%, 4.0%, and 10.2% in Antioquia, Caldas, and Cundinamarca, respectively. Mean stocking density (95% CI) was greater in Cundinamarca than Antioquia or Caldas at 3.3 (2.2, 5.0), 2.8 (2.1, 3.9) and 1.7 (1.2, 2.6) animals per ha, respectively, and was associated with hyperketonemia prevalence. Farms that abruptly stop milking cows at dry-off had 80% of the hyperketonemia events in the study. Pasture-based dairies in Colombia had lower blood BHB concentrations and estimated milk yield compared with confined production systems in temperate zones. However, geographical region, stocking density, and abrupt cessation of milking at dry-off were associated with prevalence of hyperketonemia in pasture-based dairies.

Udder and teat conformational risk factors for elevated somatic cell count and clinical mastitis in New York Holsteins.

Our primary objective was to identify udder and teat conformational risk factors associated with the occurrence of elevated somatic cell count (SCC) and clinical mastitis using a prospective cohort study design with careful assessment of exposure and disease outcomes. Mastitis prevalence was evaluated by parity across 6 sampling periods representing key physiological transitions during lactation: 0-1 day in milk (DIM), 3-5 DIM, 10-14 DIM, 50-60 DIM, 90-110 DIM, and 210-230 DIM. Cows were scored for front and rear teat length, width, end shape, and placement, fore udder attachment, udder cleft, udder depth, rear udder height, and rear udder width. Two independent multivariable logistic regression models were used to generate odds ratios (OR) for elevated SCC (≥ 200,000 cells/ml) and farm-diagnosed clinical mastitis. We identified that loose fore udder attachment (reference level: strong fore udder attachment, OR = 2.1, 95% confidence interval (CI) = 1.2-3.8) and flat teat end shape (reference level: round teat end shape, OR = 1.4, 95% CI = 1.1-1.9) increased the odds of an elevated SCC event, whereas a negative California Mastitis Test score at 0-1 DIM decreased the odds of an elevated SCC event (OR = 0.6, 95% CI = 0.4 to 0.8). Loose fore udder attachment (reference level: strong fore udder attachment, OR = 3.7, 95% CI = 1.3-10.7), flat teat end shape (reference level: round teat end shape, OR = 1.5, 95% CI = 1.0-2.4), low rear udder height (reference level: intermediate rear udder height, OR = 2.8, 95% CI = 0.3-6.2), and increasing rear teat width (OR = 2.2, 95% CI = 1.2-4.4) heightened the odds of developing clinical mastitis. We identified that within our study cohort, loose fore udder attachment and flat teat ends had an important association with increased odds of both an elevated SCC event and clinical mastitis diagnosis. The identification of these udder and teat conformational risk factors for mastitis can provide farmers an effective and inexpensive tool to manage mastitis.

The effect of the transition period and postpartum body weight loss on macrophage infiltrates in bovine subcutaneous adipose tissue.

The transition period in dairy cattle is characterized by a rapid increase in metabolic demands due to the onset of lactation in parallel with a voluntary drop in dry matter intake, which slowly increases compared with the rapidly increasing milk production. The resulting deficit in energy intake is largely met by lipolysis of adipose tissue stores liberating nonesterified fatty acids (NEFA) as energy substrates to support milk production and for the synthesis of milk fat. Previous work in cattle and other species has documented an increase in adipose tissue macrophages (ATM) during periods of feed restriction and lipolysis; however, alterations in ATM during the transition period have only recently received interest because of the role that adipose tissue remodeling and inflammation may play during this time. The primary objective of this study was to evaluate the number of macrophages in subcutaneous adipose tissue from dairy cattle at multiple time points throughout the transition period. Secondary objectives included the evaluation for potential associations of ATM with changes in body condition score (BCS) and concentrations of circulating NEFA and ß-hydroxybutyrate. Holstein cows (n = 25) were enrolled in the study 28 d before expected parturition and fed the same prepartum and postpartum rations for ad libitum consumption. On d 10 before expected parturition, and on d 4 and 21 after calving, subcutaneous adipose tissue biopsies were taken from the paralumbar fossa and preserved in formalin. Paraffin-embedded sections of tissue from each of the 25 cows at the 3 time points (total of 75 samples) were labeled with an immunohistochemical marker of macrophages, ionized calcium-binding adapter molecule 1 (Iba1, also known as allograft inflammatory factor 1). The number of Iba1-positive cells, the number of crown-like structures, and the number of immunopositive aggregates were enumerated in each sample. The number of Iba1-positive macrophages increased by 60 and 93% on d 4 and 21, respectively, when compared with the average prepartum number. Additionally, cows that lost ≥0.50 points of BCS had a 57 and 52% higher number of ATM on d 4 and 21 postpartum, respectively, when compared with cows that lost ≤0.25 points of BCS. No association was found between ATM numbers and NEFA and ß-hydroxybutyrate concentrations or milk production in early lactation. Cows experiencing a more pronounced decrease in BCS postpartum had the largest increase in adipose tissue macrophage counts, suggesting that a greater degree of adipose tissue remodeling during the period of greatest nutrient deficit may be associated with higher numbers of ATM.