Quarter-Level Analysis of Subclinical and Clinical Mastitis in Primiparous Heifers Following the Use of a Teat Sealant or an Injectable Antibiotic, or Both, Precalving

Abstract

This study investigated the effect of infusion of a bismuth subnitrate teat canal sealant or an injectable antibiotic, or both, in heifers on the cure of existing intramammary infection (IMI), incidence of new IMI, prevalence of postcalving IMI, and incidence of clinical mastitis in the first 2 wk postcalving at the quarter level. Heifers (n = 1,067) in 30 seasonally calving, pasture-fed dairy herds were randomly assigned at the heifer level to 1 of 4 treatments (no treatment; 3 intramuscular injections of 5 g of tylosin antibiotic at 24-h intervals; infusion of a teat sealant into all 4 quarters; 3 intramuscular injections of 5 g of tylosin antibiotic and infusion of teat sealant into all 4 quarters). Mammary gland secretion samples were collected from each quarter of every heifer before treatment. Heifers within a herd were enrolled on one calendar day, 27 d (on average) before the planned start of the seasonal calving period. Duplicate milk samples were collected from each gland within 5 d after calving for bacterial culture and from glands the herdowners diagnosed as having clinical mastitis. The relative risk of effect of treatment on the incidence of cure, incidence of new IMI, prevalence of postcalving IMI, and incidence of clinical mastitis were calculated at the gland level using multivariate logistic regression analyses. Neither infusion of a teat sealant nor treatment with the injectable antibiotic increased the cure of precalving IMI. Infusion of the teat sealant reduced the risk of new IMI with any pathogen by 74%, reduced the prevalence of postcalving IMI by 65%, reduced the risk of new infection with Streptococcus uberis by 70% in quarters with an IMI precalving, and reduced the incidence of clinical mastitis from which a pathogen was isolated by 70% in quarters with an IMI precalving. Parenteral antibiotic treatment had no effect on any of these outcomes. In conclusion, use of an internal teat-canal sealant in heifers reduced the postcalving IMI prevalence and the incidence of pathogen-associated clinical mastitis postcalving by decreasing the incidence of new infections over this high-risk peripartum period, and may be a useful tool for reducing the risk of mastitis in heifers.

Efficacy of an internal teat seal associated with a dry cow intramammary antibiotic for prevention of intramammary infections in dairy cows during the dry and early lactation periods

“…These facts reflect positively on the reduction of somatic cell count (SCC) and cases of clinical mastitis in the first 100 days of lactation. The same effects were observed for postpartum heifers that received internal seals during pre-partum (Parker et al 2007(Parker et al , 2008.…”

The REFLECT Statement: Reporting Guidelines for Randomized Controlled Trials in Livestock and Food Safety: Explanation and Elaboration

“…Following sampling or infusion, 0.5% effective iodine was applied by manual spraying to all teat ends. Technicians administered the first treatment of tylosin and then left labeled doses of tylosin for the remaining 2 treatments for farm staff to administer (Parker et al, 2008).…”

The influence of iodine teat dipping and an external teat sealant in heifers on bacterial isolation from quarter milk culture obtained post-calving

“…This reduction was due to reduction of new intramamammary infections. There was no cure of already infected quarters (Parker et al, 2008). However, both Schukken et al (1991) and Lam et al (1997) identified an association between the use of iodine PMTD and more clinical coliform mastitis.…”