Effects of Clinical Mastitis on Reproductive Performance in Holstein Cows

Gunay A., U. Gunay: Effects of Clinical Mastitis on Reproductive Performance in Holstein Cows. Acta Vet. Brno 2008, 77: 555-560. The objective of this study was to determine the effects of clinical mastitis on reproductive performance in 135 early lactation cows. The animals were divided into two groups according to the occurrence of mastitis as follows: group I (n = 45), clinical mastitis prior to the first artificial insemination breeding; group II (n = 45), clinical mastitis after artificial insemination and being diagnosed pregnant. Forty-five cows without any mastitis served as control group. Calving to first service intervals were significantly longer (P < 0.05) in cows with clinical mastitis before first service (group I; 95.2 ± 5.4 d) than in cows with clinical mastitis after first service (group II; 77.4 ± 8.2 d) and in control cows (75.9 ± 6.3 d). Calving to conception interval with clinical mastitis before first service (119.1 ± 10.6 d) and in cows with clinical mastitis after first service (141.7 ± 14.0 d) was significantly longer (P < 0.05) than in control (94.1 ± 10.3 d) cows. On the other hand, the number of services per conception was larger (P < 0.05) in cows with clinical mastitis after first service (3.4 ± 0.9) than in cows with clinical mastitis before first service (2.1 ± 0.9) and in cows with no clinical mastitis (1.8 ± 0.8). This study indicated that clinical mastitis during early lactation in Holstein cows had a negative impact on their reproductive performance. Dairy cows, artificial insemination, fertility, service Mastitis remains a disease causing the biggest economic losses to the dairy industry (Gill et al. 1990; Hortet and Seegers 1998; Pyorala 2002; Seegers et al. 2003). Mastitis comprises inflammation of the mammary gland, which is almost always linked with mastitis-causing organisms (O’Shea et al. 1984; Osteras and Lund 1988; Spencer 1988; Pyorala 2002). It is difficult to control because several different microbial species have the ability to infect the udder, especially during the post partum period. Pre-disposing factors are poor milking hygiene, milking machine faults, poor milking management, constitutional factors, teat injuries, teat sores and populations of pathogens on the cow’s skin and epithelia and in its environment (Edmondson 2001; O’Shea et al. 1984; Osteras and Lund 1988; Sandholm et al. 1990; Woolford 1995; Pyorala 2002). Clinical symptoms include decreased milk production, increased numbers of leukocytes in milk, altered milk composition and appearance, increased body temperature, and red, warm and swollen mammary quarters (Fleischer et al. 2001; Hansen et al. 2004) and also lower reproductive performance (Cullor 1990; Moore et al.1991; Moore and O’Connor 1993; Barker et al. 1998; Huszenicza et al. 1998; Hockett et al. 2000; Schrick et al. 2001) in lactating cows. Pregnancy rates in dairy cattle have been decreasing over the last 30 years, and some authors (Royal et al. 2000; Stevenson 2001) claim that the pregnancy rate of 50–60% in 1970’s has declined to values of 35–50 today. Peter (2004) recorded that infectious diseases can cause anovulation, fertilization failure and embryonic mortality. Nevertheless, clinical mastitis causes decreased feed intake and alters metabolite concentrations, thus changing the hormonal profile of the cow and inhibiting follicular development (Oliver et al. 2000; Young 2000). Moore et al. (1991) indicated a negative correlation between ACTA VET. BRNO 2008, 77: 555-560; doi:10.2754/avb200877040555 Address for correspondence: Dr. Aytekin Gunay Vacational School of Technical Sciences Uludag University, 16059-Gorukle, Bursa TURKEY Phone: +90 224 2942362 Fax: +90 224 2942399 E-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm clinical mastitis and reproduction due to altered inter-oestrus interval and a shorter luteal phase in cows with clinical mastitis. Cullor (1990) reported that endotoxin, a component of the cell wall of gram-negative bacteria, induced luteolysis and influenced conception and early embryonic survival apparently via the release of inflammatory mediators. The aim of this study was to determine the effect of clinical mastitis during the early post partum period on reproductive performance of Holstein dairy cows. Materials and Methods In this study 135 Holstein cows in lactation were gathered from 22 herds in the region of Bursa. The herds were kept on private family farms with milk production. All cows were milked two times daily. Average lactation number was 3.39 ± 1.32 (range = 1–7). Animals calving healthy offspring and not having retained placenta at their last calving were chosen. Genital organs of all cows were examined by rectal palpation and vaginoscopy twice within 30 days after calving. Oestrus signs were monitored by visual observation two times daily. The cows were inseminated at observed oestrus. Clinical mastitis was diagnosed by changes in the udder and milk compositions. Changes in the udder included pain, swelling, warmth and abnormal appearance of milk. Abnormal milk was detected using the strip cup test for the cow’s udder quarters. Milk samples from quarters of cows with clinical mastitis were collected aseptically. After collection the samples were examined microbiologically. Milk samples were streaked directly onto sheep blood agar and MacConkey agar plates for the isolation of bacteria. Plates were incubated at 37 °C in aerobic conditions and examined daily for 5 days for the presence of bacterial growth. The isolated bacteria were identified on the basis of cultural, morphological and biochemical characteristics (Konemann et al. 1992). Nineteen lactating cows were divided into two groups according to the time of diagnosis of mastitis and 45 non-mastitis lactating cows constituted the control group. Group I (n = 45): had their first occurrence of clinical mastitis prior to the first artificial insemination Group II (n = 45): had their first occurrence of clinical mastitis between artificial insemination and pregnancy diagnosis Control group (n = 45): had no recorded occurrence of clinical mastitis during the first 90 days after calving. Reproductive performance included calving to first service interval, calving to conception interval and the number of services per conception. Pregnancy was confirmed by rectal palpation 60–65 days after artificial insemination (AI). Data were analysed according to General Linear Model by ANOVA. Analyses were made using the statistical package of SPSS. A value of P < 0.05 was considered significant.