Identification of risk factors is important for the design of control programmes for mastitis in cows. Information about farms and management was collected at a farm visit. California Mastitis Test (CMT) was performed to assess sub-clinical mastitis, and cows, udder and milk were examined for clinical mastitis. A total of 347 lactating cows from 83 farms in the dry season (November -February) and 388 lactating cows from 89 farms in the wet season (June -October) were studied. The overall prevalence of mastitis was 19.9% and 44.8% in dry and wet seasons, respectively. The prevalence of mild mastitis was 17.3% and 40.7%, whereas that of moderate mastitis was 2.6% and 4.1% in dry and wet seasons, respectively. The prevalence of mastitis was higher (P<0.01) in wet than in dry season. On average, 18.7% quarters had mastitis during the wet season and 6.9% in the dry season. In the dry and wet seasons, respectively, 63.9% and 11.2% had completely dry floors, and the prevalence of mastitis was 22.6% and 30.0%. On the other hand, 88.8% and 36.1% of 83 farms had partly or completely wet and soiled floor and the prevalence of mastitis was 40.0% and 59.5% in the dry and wet seasons, respectively. Udder cleanliness, milk yield and peri-parturient diseases significantly (P<0.01) increased the risk of mastitis. The prevalence of mastitis is regarded as quite high. Dry and clean floor to keep cow's udder and teat clean would help control mastitis in the dairy farms of
Glutathione (GSH) at concentrations of 0.0 (control), 0.5, 1.0, 2.0 and 3.0 mM was added to chilled bull semen to determine its effects on the keeping quality of semen used for artificial insemination (AI). The semen was preserved with egg yolk citrate extender. All samples were stored at 4-8 degrees C for 5 days. Sperm motility and proportion of abnormal acrosome were assessed daily. Sperm motility was significantly (p < 0.01) higher in the semen treated with 0.5 mM glutathione than in untreated semen on each day. The optimum sperm motility (>or=50%) for AI was retained significantly (p < 0.01) for 3 days in 0.0, 0.5, 1.0 and 2.0 mM glutathione treated semen, whereas in 0.3 mM glutathione-treated semen, sperm motility was 46.8% for 3 days. Acrosomal damage was significantly (p < 0.01) reduced after addition of 0.5 mM GSH in the preserved semen. Bull semen can be preserved in chilled condition for 5 days with 0.5 mM GSH with sperm motility above 40% and 12% acrosome abnormality.
ASTRACTThe objectives of the study were to determine the prevalence of repeat breeding and its associated risk factors in cows at selected areas of Bangladesh followed by determination of an effective treatment regime for those cows. Data were collected by interviewing the owner of the cows from 172 farms having 1524 breedable cows located at one Upazila of Mymensingh, Chittagong, Khulna, Satkhira, Bogra and Dhaka districts. A total of 122 repeat breeding cows were treated and randomly distributed into 5 experimental groups for different treatment regimes. The treatment regimes were (i) single AI with injection of 500 µg of gonadorelin, (ii) intra uterine infusion of 4.0 million i.u. penicillin daily for 3 days followed by single AI at next estrus, (iii) same time AI with double doses of semen, (iv) two times AI at 8 hours interval and (v) single AI without any intervention (used as control group). Information was collected for all treated cows for returning to estrus at 20-22 days post-AI. If the cow did not return to estrus at 20-22 days post-AI, the cows were examined for pregnancy by per rectal palpation of genital tract at 60-90 days post-AI. The pregnancy of the treated cows was used as the indicator of success of each treatment regime. The overall prevalence of repeat breeding in cows was 11.5%. The breed of cows, herd BCS and farm size influenced the prevalence of repeat breeding in cows. The age, parity, BCS and milk yield influenced the occurrence of repeat breeding in individual cows. The significantly higher proportion of cows recovered when AI was done using double doses of semen (52.8%) or single AI was done with GnRH administration (51.9%) than no intervention control (30.4%). In conclusion, repeat breeding cows may be inseminated with double doses of semen or with single AI with GnRH administration for improvement of conception.
This study focused on the use of radioimmunoassay of progesterone in milk for the diagnosis of post-partum ovarian cyclicity and accurate detection of oestrus and non-pregnancy in cows in the artificial insemination (AI) programme in Bangladesh. In Investigation 1, milk samples were collected on day 0 (day of AI), day 9-13 and day 21-24 from 444 milking cows of various breeds presented for the first postpartum insemination by 413 farmers living at 182 villages/regions in Mymensingh District from 6 AI centres and sub-centres. Each cow was then examined three times after each AI until it stopped returning to oestrus. Sixty to 90 days after the last AI, the cows were examined per rectum to confirm the pregnancy. Milk progesterone data on day 21-24 contributed to a clear diagnosis with respect to non-pregnancy in 100% cows, indicating a possible use of this progesterone assay for identifying non-pregnant cows in AI programmes. In Investigation 2, milk progesterone was monitored two times in a month with a 10-day interval in 88 cows. The samples were taken between 10 days after calving and the first detected oestrus, followed by two more samples 10 days apart. The proportion of cows accurately detected in oestrus was 30%. Another 30% were stated to be in oestrus when they were not (false positive) and 40% were not detected when they were in oestrus (false negative). The mean intervals between calving and oestrus and between calving luteal activity were 40 to 362 days (median=120, n=82) and 34 to 398 (median=111, n=64) days, respectively. The body condition scores at calving and at the initiation of luteal activity influenced the interval between calving and luteal activity (p < 0.05). Cows suckled twice daily initiated luteal activity earlier than their counterparts suckled several times daily (p < 0.05). Determination of progesterone in milk on day 21-24 is a good means for detecting non-pregnant cows.
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