Abstract Objective —To determine whether results obtained for milk and serum samples with ELISAs intended for diagnosis of paratuberculosis in dairy cows were comparable to results obtained by means of mycobacterial culture of fecal samples. Design —Cross-sectional study. Animals —689 lactating dairy cows in 9 Ontario herds. Procedure —Milk, serum, and fecal samples were obtained from all cows. Fecal samples were submitted for mycobacterial culture. Serum samples were tested with a commercially available ELISA for antibodies against Mycobacterium paratuberculosis , and preserved milk samples were tested with an indirect ELISA for antibodies against M paratuberculosis . Results —Results were positive for 130 of the 689 (18.9%) serum samples, 77 of the 689 (11.1%) milk samples, and 72 of the 689 (10.4%) fecal samples. The level of agreement between results for milk and serum samples was only moderate. Proportions of positive results for serum and fecal samples were significantly different, but proportions of positive results for milk and fecal samples were not significantly different. In addition, results for milk samples had a higher level of agreement with results of mycobacterial culture than did results for serum samples. Conclusions and Clinical Relevance —Results suggest that the indirect ELISA used on milk samples may be a convenient method of detecting paratuberculosis in dairy herds. ( J Am Vet Med Assoc 2005; 226:424–428)
This randomized controlled trial investigated the effects of temporarily reducing milking frequency (MF) on the resolution of ketosis and milk production in dairy cows in early lactation. To detect ketosis [blood β-hydroxybutyrate (BHB) ≥1.2 mmol/L], Holstein cows were screened daily from 3 to 16 d in milk using a cow-side meter. Cows diagnosed with ketosis (n = 104) were randomly assigned to twice-daily milking (TDM) or reduced to once-daily milking (ODM) for 2 wk, then returned to twice-daily milking. Both treatment groups received a 5-d treatment of an oral propylene glycol drench (PG; 300 g) beginning on the afternoon of the diagnosis; cows received additional 5-d PG treatments if they had a ketotic test result (blood BHB ≥1.2 mmol/L) at least 4 d after finishing the first PG treatment. Blood BHB tests were conducted for the first 3 d after ketosis diagnosis, and then once every 3 d for 21 d of trial (DOT). Milk and milk component data were collected weekly for 15 wk following trial enrollment. The ODM group showed rapidly and markedly decreased blood BHB concentrations (primiparous cows: 1 DOT, 0.92 ODM vs. 1.22 TDM, 15 DOT, 0.55 vs. 0.81 mmol/L; multiparous cows: 1 DOT, 1.01 vs. 1.40, 15 DOT, 0.78 vs. 1.65 mmol/L). In addition, a logistic regression model indicated that ODM cows were less likely to have blood BHB concentrations ≥1.2 mmol/L [primiparous cows: 3 DOT: ODM 1% (95% confidence interval: 0–10%) vs. TDM 43% (30–58%), 15 DOT ODM 0% (0–0.2%) vs. TDM 22% (13–36%); multiparous cows: 3 DOT: ODM 33% (24–44%) vs. TDM 59% (48–69%), 15 DOT ODM 20.9% (13–31%) vs. TDM 64% (53–74%)]. The proportion of ODM cows that required additional treatments of PG were substantially lower than the TDM group (ODM: 39%; TDM: 64%) than the TDM cows during the initial 21-d period. However, during the 2-wk treatment period, cows in the ODM group produced 26% less milk and 25% less energy-corrected milk than the TDM cows. During wk 3 to 15, when all cows were milked twice daily, ODM cows produced less milk (−14%) and energy-corrected milk (−12%) compared with the TDM group. Milk protein percentage was greater, and milk fat percentage and linear score tended to be greater in the ODM group over 15 wk. In conclusion, a 2-wk reduction of MF in ketotic cows from twice to once daily with treatment with PG resolved ketosis and decreased blood BHB concentrations more effectively than treating TDM cows with PG alone. However, the 2-wk MF reduction had immediate and long-term (up to 13 wk after cessation of MF reduction) negative effects on milk production.
Particle size of forages and total mixed rations plays an important role in the health and performance of dairy cattle. Objective of this study was to determine the effect of forage and total mixed ration (TMR) particle size on various health and production parameters in Ontario dairy herds.
The objective of this study was to quantify the effects of supplementing a low level of dry glycerol product pre- and postpartum on the feeding behavior, lying behavior, and reticulorumen pH of dairy cows. Multiparous Holstein dairy cows (n = 60) were enrolled in a 2 × 2 factorial design study. Twenty-one days before expected parturition, cows individually received a dry cow diet with: 1) 250 g/d glycerol supplementation (GLY; 66% pure glycerol, United States Pharmacopeia grade), or 2) no supplementation (CON). Following parturition, cows were individually assigned to either: 1) 250 g/d glycerol product (GLY; 66% pure glycerol), or 2) no supplementation (CON) to their partial mixed ration (PMR) for the first 21 d in milk (DIM). All cows were milked by an automated milking system (AMS) and offered a target of 5.4 kg/d pellet (23% of target total DMI). For both treatment periods, cows were individually assigned to automated feed bins to measure PMR feeding behavior. Rumination time and lying behavior were monitored with electronic sensors for the whole study (−21 to 21 DIM). Reticulorumen pH boluses were administered to a subset of cows (n = 40) where pH was recorded every 10 min from 21 d prepartum to 21 d postpartum. Prepartum, cows fed GLY had fewer, larger meals, and spent 20.2% more time feeding than CON while consuming feed at a similar rate. Cows on the CON prepartum spent more time lying down in more frequent bouts in the 21 d before calving. Following parturition, cows that received GLY prepartum continued to devote more time to eating, while tending to spend less time ruminating per kg DMI. Cows receiving CON postpartum had larger meals with longer intervals between meals. In the first 21 DIM, cows receiving CON prepartum tended to have shorter, but significantly more frequent, lying bouts than cows fed GLY prepartum. Glycerol supplementation pre- and postpartum resulted in less time spent lying down following parturition. Minimal differences between treatments were observed for pre- and postpartum sorting behavior or reticulorumen pH. Overall, supplementation of glycerol pre- and postpartum altered cow time budgets, with cows spending more time eating pre- and postpartum, less time lying pre- and postpartum, and having fewer, larger meals prepartum when receiving glycerol prepartum and with cows having slower feeding rates and smaller meals following parturition with postpartum glycerol supplementation.
