monensin and Mastitis--Bovine

To assess the effect of applying an external teat sealant or a slow-release intraruminal monensin capsule pre-calving on the prevalence and incidence of subclinical or clinical mastitis in dairy heifers post-calving.. The studies were undertaken in 13 herds. In two herds application of an external teat sealant was compared with a negative control; in nine herds treatment with monensin was compared with controls, and in two herds treatments were applied in a 2 x 2 factorial design. Heifers were randomly assigned within herd to be treated with a slow-release intraruminal device containing 32 g monensin (n=383), or left as untreated controls (n=389), approximately 30 days before the start of the spring calving period; or to be treated with a latex external teat sealant (n=206) when calving was impending, or be left as untreated controls (n=205). Milk samples were collected from each gland between 0 and 5 days after calving and from any gland diagnosed with clinical mastitis. The effect of the treatments on the prevalence of intramammary infection (IMI), i.e. subclinical mastitis, and clinical mastitis were initially analysed at the univariate level, with associated variables (p<0.2) being used in construction of multivariable models.. The prevalence of IMI was 18.4% at the gland level, and coagulase-negative staphylococci followed by Streptococcus uberis were the most common isolates. Treatment with an external teat sealant reduced the prevalence, compared with controls, of any IMI (12.1 (SE 1.7)% vs 16.5 (SE 2.1)%, respectively; p=0.05) or IMI caused by a major pathogen (3.8 (SE 0.8)% vs 6.0 (SE 1.1)%, respectively; p=0.05). Monensin treatment did not affect the prevalence of any IMI (p=0.68) or IMI due to a major pathogen (p=0.11). The cumulative incidence of clinical mastitis was 14.2%. Neither monensin treatment (p=0.47) nor application of an external teat sealant (p=0.71) altered the risk of clinical mastitis. There was no interaction between the monensin and external teat sealant in the two herds where the treatments were applied in a 2 x 2 factorial design.. Application of an external teat sealant resulted in a lower prevalence of any IMI and of an IMI caused by a major pathogen. Despite monensin reducing the mobilisation of body tissue and the risk of subclinical ketosis, it had no effect on the prevalence or incidence of IMI or clinical mastitis.. Application of an external teat sealant is an option for reducing the prevalence of IMI in pasture fed dairy heifers.

Topics: Administration, Oral; Administration, Topical; Animals; Cattle; Colony Count, Microbial; Dairying; Female; Incidence; Ionophores; Lactation; Latex; Mammary Glands, Animal; Mastitis, Bovine; Monensin; New Zealand; Pregnancy; Prevalence; Severity of Illness Index; Streptococcus; Treatment Outcome

Topics: Animals; Anti-Bacterial Agents; Biofilms; Cattle; Female; Gram-Positive Bacteria; Ionophores; Lasalocid; Mastitis, Bovine; Microbial Sensitivity Tests; Monensin; Pyrans; Staphylococcal Infections; Staphylococcus; Streptococcal Infections; Streptococcus

Associations of herd milk production and management variables to a return-over-feed (ROF) herd profit index were examined among 95 dairy farms. The ROF index is derived from 2 important determinants of profit on dairy farms: milk income and feed cost. All producers were participants in the Dairy Herd Improvement (DHI) ROF program in Ontario, Canada during 2002. Nutrition, housing, health, and other management data were collected through a phone survey of herd managers. Herd milk production, milk component percentages, and somatic cell count data were obtained from the Ontario DHI database. The linear regression model accounting for significant variation in ROF with highest R2 (0.66) included standardized milk production, milk protein percentage, milk fat percentage, and use of monensin in lactating cow rations. A 1-kg increase in standardized milk production (kg/d per cow) or a 0.1 percentage unit increase in milk protein was associated with $0.35/d per cow or $0.26/d per cow increase, respectively, in the ROF of the dairy herd. However, a 0.1 percentage unit increase in milk fat was associated with a $0.10/d per cow decrease in ROF, probably because of a negative association of milk fat with milk yield. Use of monensin in lactating cow rations was associated with a $0.39/d per cow increase in ROF. In a separate model (R2 = 0.27) that examined management factors independent of production variables, herds using 3 times daily milking had a $1.25/d per cow higher ROF vs. herds using twice daily, whereas use of an Escherichia coli mastitis vaccine was associated with $0.59/d per cow higher ROF. Production-related variables accounted for more variation in the ROF index than management variables, and the latter, e.g., use of monensin, only marginally increased R2 of production-based regression models.

Topics: Animal Feed; Animals; Cattle; Costs and Cost Analysis; Dairying; Escherichia coli Infections; Escherichia coli Vaccines; Female; Lactation; Linear Models; Lipids; Mastitis, Bovine; Milk; Monensin; Ontario

Twelve trials designed to test the effect of monensin on milk production were carried out at eight different research farms. Data from these studies were evaluated for effects of monensin on health and reproduction. Monensin was added to the concentrate starting either 2 wk before (293 cows) or 5 wk after calving (601 cows) for periods ranging 16 to 37 wk. Applied after calving, the incidence of clinical mastitis was reduced in the monensin-treated animals. Monensin decreased the rate of intramammary infection (approximated by a change from below to above 250,000 somatic cells in milk) in first lactation heifers by 13%. Indicated by an adjusted incidence rate ratio of 0.58 (P = 0.03), the case incidence of noninfectious lameness decreased from 31% in control cows to 18% in cows receiving monensin before calving. The time from calving to first service was shorter for cows fed monensin before calving. Monensin reduced calving to conception intervals in cows with endometritis during the pretreatment period. No significant effects of monensin were observed for the duration of intra mammory infection (somatic cells in milk above 250,000), infectious lameness, endometritis, cystic ovarian disease, a summary category of 'other diseases,' times from calving to first observed estrus, and from first service to conception.

Topics: Animals; Cattle; Cell Count; Female; Fertility; Health Status; Incidence; Ketone Bodies; Lactation; Lameness, Animal; Mastitis, Bovine; Milk; Monensin; Pregnancy; Recurrence; Reproduction; Time Factors