Randomised controlled trials demonstrate efficacy of a novel internal teat sealant to prevent new intramammary infections in dairy cows and heifers.

AIMS: The main aim was to investigate the effectiveness of a novel internal teat sealant (ITS) formulation containing bismuth subnitrate and the antiseptic chlorhexidine, in adult cows (Trial A) and nulliparous heifers (Trial B), to reduce the incidence of new intramammary infection (IMI) between treatment and calving and reduce the prevalence of IMI within 6 days following calving. METHODS: In Trial A dairy cows (n=326) without history of clinical mastitis and with a maximum composite milk somatic cell count <200,000 cells/mL during the current lactation were enrolled from three spring-calving mainly pasture-based herds immediately following the final milking. In Trial B all heifers (n=166) were enrolled from two herds approximately 3 weeks before the start of calving. Glands were randomly assigned to controls or treatment with ITS, and mammary secretion samples were taken from all glands prior to treatment, and on two occasions 0-4 and 3-6 days post-calving to determine the incidence of new IMI and the prevalence of IMI immediately post-calving. Additionally, cows in Trial A were monitored for cases of clinical mastitis (CM) in the non-lactating period and animals in both trials were monitored for cases of CM within 30 days of calving. RESULTS: The ITS reduced the estimated incidence of new IMI with both major and any pathogens compared to control glands in cows (6.2 vs. 14.2% and 14.7 vs. 32.8%, respectively) and in heifers (3.0 vs. 13.1% and 13.4 vs. 25.3%, respectively) (p<0.001). The ITS reduced the estimated prevalence of a major or any pathogen compared to untreated controls at both 0-4 and 3-6 days post-calving, in both cows and heifers. Additionally, the ITS reduced the incidence of CM in the non-lactating period in cows (-1.0%, p=0.01) and in the 30 days following calving in heifers (-2.0%, p=0.06), and tended to reduce the estimated incidence of CM in cows post-calving (-1.7%, p=0.10). CONCLUSIONS: The novel ITS reduced the incidence of new IMI, and the prevalence of IMI at calving in both adult cows and heifers, and reduced the incidence of CM in the non-lactating period of cows and in the first 30 days after calving in heifers. CLINICAL RELEVANCE: The results of these trials demonstrate the efficacy of a novel ITS for the control of mastitis in likely uninfected dairy cows over the non-lactating period and in heifers in late pregnancy.

The use of equine chorionic gonadotropin in the treatment of anestrous dairy cows in gonadotropin-releasing hormone/progesterone protocols of 6 or 7 days.

In seasonally calving, pasture-based dairy farm systems, the interval from calving to first estrus is a critical factor affecting reproductive efficiency. This study evaluated the effects of equine chorionic gonadotropin (eCG) on the reproductive response of lactating, seasonally calving dairy cows diagnosed with anovulatory anestrus by rectal palpation. Cows on 15 commercial dairy farms were selected for initial inclusion based on nonobserved estrus by 7 d before the planned start of mating. All cows were palpated rectally and evaluated for body condition score and ovary score, and were included for treatment according to the trial protocol if diagnosed with anovulatory anestrus. All cows received a standard anestrous treatment protocol consisting of insertion of a progesterone device, injection of 100 µg of GnRH at the time of device insertion, and injection of PGF(2α) at device removal (GPG/P4). Cows were randomly assigned to 1 of 2 groups (6 d or 7 d) for duration of progesterone device insertion. Within each of these groups, cows were further randomly assigned to receive either 400 IU of eCG at device removal or to remain untreated as controls, resulting in a 2×2 arrangement of treatment groups: (1) 6-d device and no eCG (n=484); (2) 6-d device and eCG (n=462); (3) 7-d device and no eCG (n=546); and (4) 7-d device and eCG (n=499). Cows were detected for estrus from the time of progesterone device removal and were inseminated; those not detected in estrus within 60 h after progesterone device removal received 100 µg of GnRH and were inseminated at 72 h. The primary outcomes considered were proportion of cows conceiving within 7 d of the beginning of breeding (7-d conception rate; 7-d CR), proportion pregnant within 28 d (28-d in calf rate; 28-d ICR), and days to conception (DTC). We found no significant differences between the 6- and 7-d insertion periods and found no 6- or 7-d insertion period × eCG treatment interactions. Inclusion of eCG into either length of GPG/P4 protocol increased 7-d CR (36.0 vs. 30.6%) and 28-d ICR (58.6 vs. 52.3%) and decreased median days to conception. The use of eCG in GPG/P4 breeding protocols will improve reproductive efficiency in seasonally calving, anestrous dairy cattle.

The comparative efficacy of two long-acting dry-cow cephalonium products in curing and preventing intramammary infections.

AIMS: To test equivalence between two different cephalonium dry-cow therapy (DCT) products with regard to the incidence of bacteriological cure of existing infections of quarters, the incidence of new intramammary infections (IMI) from 2-5 days postpartum and the incidence of clinical mastitis from drying-off to 21 days postpartum. METHODS: All cows (n=1,570) on four commercial dairy farms in Southland were eligible for inclusion. Power analysis using a variance inflation factor indicated a required minimum of 2,101 quarters per treatment group. Cows were blocked by herd, parity, previous history of mastitis and most recent somatic cell count (SCC), and then randomly allocated to either of two cephalonium treatments at the cow level, viz the treatment group (new formulation cephalonium) or the positive control group (existing reference formulation cephalonium). All quarters within a cow were assigned the same treatment. Samples collected from all quarters with a SCC ≥500,000 cells/mL at drying-off, and those with a positive culture postpartum were cultured, as well as samples from all quarters collected between 2-5 days postpartum. All cases of mastitis were recorded and sampled for culture. The risk of quarter-level incidence of bacteriological cure, IMI and clinical mastitis was modelled using a GLM and generalised estimating equation (GEE), including the effects of treatment group, age,farm, udder-health status at drying-off and length of dry period. RESULTS: For 829 infected quarters, the estimated incidence of bacteriological cure for all pathogens was 78.0 (95% CI=64.3-91.6)% for the treatment group and 75.7 (95% CI=61.6-89.8)% for the positive control group (p=0.71). Incidence of cure varied with the farm (p=0.001), type of pathogen pre-treatment (p=0.009) and log(10)SCC at drying-off (p<0.001). For 4,530 quarters, the estimated incidence of new IMI, with any pathogen, for treatment and positive control groups was 16.1 (95% CI=13.1-19.7)% and 16.0 (95% CI=13.0-19.5)% respectively (p=0.91). Incidence of IMI varied with farm (p<0.001), pathogen and SCC status before treatment (p<0.001), and length of the dry period (in days) (p<0.001). For 5,136 quarters, the estimated incidence of clinical mastitis was 1.0 (95% CI=0.5-1.7)% in the treatment group and 1.1 (95% CI=0.6-2.0)% in the positive control group (p=0.64). CONCLUSIONS: Use of the two different cephalonium products at drying-off in four dairy herds in Southland resulted in equivalence with respect to incidence of bacteriological cure of existing infections, incidence of new IMI postpartum, and incidence of clinical mastitis in early lactation.

Use of equine chorionic gonadotrophin in synchronised AI of seasonal-breeding, pasture-based, anoestrous dairy cattle.

In seasonally calving dairy areas, a critical index of efficiency and profitability is the ability to maintain a short annual calving spread. In essence, this means that all cows need to conceive within 90 days of calving. Anovulatory anoestrus (AA) is a major barrier to reproductive performance under these conditions and the successful treatment of AA is an important aspect of reproductive intervention. The present paper reviews regimens used to treat AA in New Zealand and reports on a large-scale field trial investigating the effects of equine chorionic gonadotrophin (eCG) within a proven efficacious treatment protocol. The administration of eCG at the time of removal of a progesterone-releasing device in an 8-day, oestradiol benzoate (EB)-based treatment protocol increased the percentage of cows in calf after 7 and 28 days of breeding. The interaction between cow age and treatment with eCG was significant, with cows over 5 years of age having higher conception rates (P = 0.002) and 7 day in-calf rates (P = 0.002) than cows on a standard 8-day treatment protocol without eCG. The addition of eCG to a standard 8-day EB/progesterone protocol can improve reproductive success in seasonally calving AA dairy cows.

An overview of the eradication of Brucella melitensis from KwaZulu-Natal.

Brucella melitensis is a Gram-negative bacterium whose primary hosts are goats and sheep. Like the other BrucelIa spp., with the exception of Brucella ovis, it is not particularly host specific as it is pathogenic for a variety of other mammal species including humans. In humans the disease caused by it is rated as one of the most important zoonoses. Three outbreaks have been recorded in goats and sheep in South Africa; the first outbreak occurred in sheep in 1965 in the Mpumalanga and Northern Provinces (then both part of the Transvaal Province), the second occurred in sheep in 1989 near Pretoria, Gauteng Province, and the third and current outbreak was diagnosed in a flock of goats in northern KwaZulu-Natal in September 1994. Following the initial diagnosis of B. melitensis in north-eastern KwaZulu-Natal, a serological survey was conducted in order to identify foci of infection in the goat and sheep populations. Six positive foci were identified. In March 1996 a test-and-slaughter eradication campaign was initiated in these areas. Initial test results revealed a prevalence of between 1.23% and 4.02 %. All positive animals were identified and slaughtered. Eradication programmes were repeated between March 1996 and June 2000, in the populations at risk, and the disease prevalence was reduced in all the affected populations.

Parasites of domestic and wild animals in South Africa. XL. Ticks on dogs belonging to people in rural communities and carnivore ticks on the vegetation.

Ixodid ticks were collected at weekly intervals from February 1999 to April 2000 from domestic dogs belonging to people in rural communities in north-eastern KwaZulu-Natal. Seven ticks were identified to species level and adult Haemaphysalis leachi followed by immature Amblyomma hebraeum and adult Rhipicephalus simus were the most prevalent. Infestation with adult H. leachi was most intense during February and March 1999 and from January to April 2000, and least intense during October 1999. Infestation with adult R. simus was most intense during February and March 1999 and least during July and September of the same year. For 12 consecutive years, from August 1988 to July 2000, free-living ticks were collected at monthly intervals from the vegetation of two landscape zones in the Kruger National Park. Most adult H. leachi were collected in the one zone from March to June, and no ticks were collected in October, whereas, with the exception of March, most were collected in the other zone during the period January to June, and only one tick was collected in October. Most adult R. simus were collected during February and March at both localities and only a single tick was collected in September. Adult Rhipicephalus turanicus was present only in the one zone and was collected only from January to June.