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G P Keefe

Publications and source records attributed to G P Keefe.

23 records · Page 2Linked to original sources
PubMed1999

Relationships between bulk-tank antibodies to Ostertagia ostertagi and herd-management practices and measures of milk production in Nova Scotia dairy herds.

Monthly bulk-tank milk samples were obtained from 415 Nova Scotia dairy herds in each of the months of July-September 1998 and tested using an indirect microtitre ELISA against a crude saline-extract, whole-worm Ostertagia ostertagi antigen. ELISA results (optical densities (ODs)) were consistent across months (r=0.85) but there was considerable variation among herds. A questionnaire was sent by mail to all producers; information on management factors that would potentially influence parasite burdens in the herds was obtained from 239 farms. Data on annual milk production, summer milk production (July-September) and seasonal decline in milk production were obtained from the Animal Productivity and Health Information Network (APHIN) database. Associations between management practices and ODs, and between ODs and milk-production parameters were studied. Some management practices known to be associated with parasite burdens had expected directions of association with the ODs, giving supporting evidence that the ELISA is a reasonable measure of parasite burden. Most notably, ODs were increased with greater exposure of heifers or milking cows to pasture. ODs were not associated with either annual milk production or seasonal decline in milk production. However, there was a substantial relationship between the herd OD value and the level of milk production during the summer. An increase in the OD from 0.58 to 0.83 (the interquartile range of ODs) was associated with a reduction in production of 1.25kg/cow/day.

Animal Husbandry↗
PubMed1998

Measures of estrus detection and pregnancy in dairy cows after administration of gonadotropin-releasing hormone within an estrus synchronization program based on prostaglandin F2 alpha.

The objective of this study was to assess the use of GnRH in a controlled breeding program (7 d prior to the second of two injections of PGF2 alpha, 14 d apart) as a means to improve the expression and detection of estrus, first service conception rate, and overall pregnancy rate of lactating dairy cows. On 17 farms, 348 cows were assigned randomly to either of two breeding programs prior to first insemination. Cows in both programs received PGF2 alpha approximately 2 wk prior to the end of a herd-specific voluntary waiting period for breeding. One group received GnRH 1 wk later, 7 d prior to the second of two injections of PGF2 alpha. Control cows received saline and a second injection of PGF2 alpha at corresponding times. Cows were observed for 7 d and were bred by artificial insemination following detection of estrus. There were no differences between programs in estrus detection rate, observed signs of estrus, conception rate, days to first service, or interval from calving to conception. The means and standard deviations of the interval from PGF2 alpha to estrus were not different between programs. Administration of GnRH 1 wk prior to PGF2 alpha did not alter the expression of estrus or fertility in lactating dairy cows. In this study population, no advantage was found for the addition of GnRH to a controlled breeding program that was based on two administrations of PGF2 alpha at a 14-d interval.

Animals↗
PubMed1997

Herd prevalence and incidence of Streptococcus agalactiae in the dairy industry of Prince Edward Island.

Herd prevalence and incidence of mastitis caused by Streptococcus agalactiae was determined for dairy cattle on Prince Edward Island during December 1992 and June 1994. For each census, bulk tank milk samples from all dairy herds (n = 452) in the province were tested on two occasions, and the results were interpreted in parallel. The combined sensitivity of the testing protocol was estimated to be 91%. The confirmatory latex agglutination test had previously reported specificities approaching 100%. Therefore, the estimated specificity of the testing protocol was assumed to be 100%. The apparent prevalence of S. agalactiae in December 1992 and in June 1994 was 17.7 and 13.1%, respectively. Based on the characteristics of the test, the estimated true prevalence was 18.9% in December 1992 and 14.4% in June 1994. Infection with S. agalactiae was associated with elevated bulk tank somatic cell count (SCC) and elevated standard plate counts. Economic losses associated with S. agalactiae were attributed to production losses (associated with bulk tank SCC), milk quality penalties (associated with bulk tank SCC and standard plate count), and decreases in milk quality (associated with bulk tank SCC). For herds that had been negative for S. agalactiae in December 1992, evaluation in June 1994 yielded an incidence of new infections of 3.51 per 100 herds per year.

Animals↗
PubMed1997

Streptococcus agalactiae mastitis: a review.

Streptococcus agalactiae continues to be a major cause of subclinical mastitis in dairy cattle and a source of economic loss for the industry. Veterinarians are often asked to provide information on herd level control and eradication of S. agalactiae mastitis. This review collects and collates relevant publications on the subject. The literature search was conducted in 1993 on the Agricola database. Articles related to S. agalactiae epidemiology, pathogen identification techniques, milk quality consequences, and control, prevention, and therapy were included. Streptococcus agalactiae is an oblique parasite of the bovine mammary gland and is susceptible to treatment with a variety of antibiotics. Despite this fact, where state or provincial census data are available, herd prevalence levels range from 11% (Alberta, 1991) to 47% (Vermont, 1985). Infection with S. agalactiae is associated with elevated somatic cell count and total bacteria count and a decrease in the quantity and quality of milk products produced. Bulk tank milk culture has, using traditional milk culture techniques, had a low sensitivity for identifying S. agalactiae at the herd level. New culture methods, using selective media and large inocula, have substantially improved the sensitivity of bulk tank culture. Efficacy of therapy on individual cows remains high. Protocols for therapy of all infected animals in a herd are generally successful in eradicating the pathogen from the herd, especially if they are followed up with good udder hygiene techniques.

Animals↗