The use of heat mount detectors in a large Iranian dairy herd

Heat mount detectors were applied in a large Iranian dairy herd in an attempt to appraise their value for fertility improvement. A total of 100 cows with a recorded anoestrous period of at least 60 days were selected, 69 of them suffering from suboestrus or silent heat and 31 from true anoestrus due to inactive ovaries. The results indicate that inaccurate observation of heat is a major limiting factor in the reproductive performance of this herd and that heat detectors could be a valuable tool for improvement of oestrus detection and consequent reduction of the interval from calving to conception.     

The Dairy Herd Management System. Application to dairy herd reproductive management as a bureau and on-farm system

This article describes the field use of the Dairy Herd Management System Microcomputer software. The practical experiences gained from the use of the program in dairy reproductive management are discussed for operation both as a bureau service and as an on-farm system.     

Use of dairy herd improvement monthly summary data to monitor intervention strategies in a dairy herd experiencing suboptimal reproductive performance and reduced milk production

An 87-cow dairy herd with a history of high milk production was visited because of reduced reproductive performance and decreasing milk production. Cows that had recently delivered calves were thin, and many cows had evidence of previous episodes of laminitis. A ration that provided an unfavorable forage-to-concentrate ratio was being fed. In addition to various diagnostic efforts, management changes that were made included alteration of the ration and installation of a computer-operated feeder. After the initial visit, the herd was monitored for 30 months by the use of Dairy Herd Improvement monthly herd summary data. Several potential strengths and weaknesses of using selective production and reproduction monthly summary statistics were illustrated by this study. Milk production, as monitored by mature-equivalent production and average relative value-milk, continued to increase throughout the 30 months after intervention. Reproductive performance, as indicated by first-service conception rate, did not begin to improve until the final 6 months of the monitoring period. Overall, in addition to assisting in diagnostic efforts. Dairy Herd Improvement monthly herd summary data may be used to establish goals, provide comparisons, and maintain producer interest after practitioner intervention in herd management.     

Variability of acetone in milk in a large low-production dairy herd: a longitudinal case study

The objective of this study was to relate acetone in milk with cow and management factors in one low producing dairy herd (5260 kg milk per 305-day lactation). Milk acetone was measured in regular monthly milk samples one to three times within 100 days of lactation in 4433 lactations (2639 cows, 7800 measurements) from one herd over a period of 32 months (1988-91). Associations between milk acetone and cow factors and surrogate measures of management were evaluated by variance components of multiple fixed effect models. Lactation stage, calendar month of study, production groups and milk yield were strong, and percentage milk fat and parity were weak predictors of milk acetone. There was a trend of increasing body weight loss from the first to the second month of lactation with increasing milk acetone level. A substantial increase in milk production in 1991 was accompanied by an almost twofold rise in milk acetone. It was concluded that environmental parameters had strong relationships with milk acetone even in this low-producing herd.     

Cloprostenol as an aid in dairy herd management: 1. Mating management

An AB programme restricted to 14 days through the use of mated, 135 were treated after selection on pre-mating oestrus dates or rectal examination. Treatment was administered on the 6th day of mating. Untreated cows were inseminated, on detection of oestrus, throughout the 14 days. Nine of 135 treated cows were inseminated within 48 hours, 50 at 72 hours only, 75 at both 72 and 96 hours and one at 96 hours after treatment. All cows in season were inseminated, irrespective of recent insemination. Prolonged and split heats, and short cycles (less than 14 days), occurred in treated and untreated cows.

AB conceptions confirmed in those cows retained in the herd were 623% of untreated cows (66.9% of those which were inseminated) and 69.1% of treated.

The conceptions achieved in this abbreviated AB programme are equal to those normally achieved after 7 weeks of AB. Mating management is discussed; the release of labour from AB involvement 4 weeks earlier than usual is a major advantage of this technique.     

Associations between dairy herd management factors and bulk tank milk antibody levels against Ostertagia ostertagi

A cross-sectional questionnaire survey was performed on dairy herds in Flanders (Belgium) to detect management factors that are associated with an increased gastrointestinal parasite infection level of adult dairy cows. At the end of the grazing season, information concerning general herd factors, pasture management and anthelmintic treatment strategy was obtained from 956 herds. A bulk tank milk sample was obtained from 779 out of the 956 herds and the antibody levels (ODR) against Ostertagia ostertagi were determined. The associations between ODR and herd management factors were studied by two linear regression models. The first model evaluated the effect of general herd factors and the level of the cows' exposure to pasture. Large sized herds had significantly lower ODRs as compared to medium (P=0.001) or small sized herds (P=0.03). Herds with only dairy cows had lower ODRs than herds with both dairy and beef cows (P=0.02). An increased exposure to pasture of the cows was associated with higher ODRs (P<0.001). The second model was built to evaluate the effect of pasture management factors and anthelmintic treatment strategy. Later turn-out on pasture (P<0.001) and mowing (P=0.002) were both significantly associated with lower ODRs. Cows that had a restricted grazing time per day tended to have lower ODR than cows that grazed 24 h per day (P=0.07). An increased exposure to pasture of the heifers was significantly associated with higher ODRs (P=0.001). No associations were found between ODR and calf related management factors, anthelmintic treatment strategy, time of turn-in, rotational grazing type or stocking rate. Later turn-out on pasture, mowing and restricting the grazing time per day are factors that can be applied immediately on dairy farms to reduce economical losses due to gastrointestinal nematodes.     

The effect of mastitis on milk progesterone concentration in dairy cows

A within cow comparison was made between milk progesterone levels in healthy and mastitic quarters. Material was collected from cows with mastitis induced by bacterial inoculation, or by inoculation with bacterial endotoxin. Furthermore material from cows with spontaneous subclinical mastitis was used. Milk progesterone levels were lowered due to mastitis. However, the decrease was not large enough to cause misinterpretation of where in the oestrous cycle (luteal phase or non-luteal phase) the samples were taken.     

Implementation and use of a microcomputer-based management information system to monitor dairy herd performance

A microcomputer-based herd management information system was implemented as part of the herd health program provided to 13 dairy clients by the Ontario Veterinary College, University of Guelph. The study was conducted over a two year period. Data were collected from on-farm event diaries, veterinary visit reports, and production testing information. Selected indices of reproduction, udder health, production, and heifer performance were reported. It was concluded that the implementation of a microcomputer-based information management system, operated as a bureau service, was feasible. However, limitations to the implementation in veterinary practice were identified.     

The milk progesterone test as an aid to the diagnosis of cystic ovaries in dairy cows

Two field trials were carried out by five experienced veterinary surgeons to evaluate the milk progesterone test as an aid to the differential diagnosis of cystic ovaries in dairy cows. Of 200 cystic cows, 71 per cent were diagnosed clinically as follicular and 29 per cent as luteal cases; 80 per cent of the cases occurred in the six winter months November to April. The progesterone assay indicated that the diagnosis was correct in 84 per cent of the follicular cases but only 54 per cent of the luteal cases. Seventy-four per cent of the confirmed cystic cases responded to treatment within two weeks according to milk progesterone tests and there were no significant treatment differences. Overall, 80 per cent of the cows became pregnant on average 38 days after treatment having received an average of 1.70 inseminations each. Milk yield data in the first trial indicated that the cystic cows were not significantly higher yielders than their herd-mates.     

The use of milk progesterone analysis to monitor reproductive activity in the camel (Camelus dromedarius)

Milk progesterone profiles were used to monitor the ovarian changes during the post-partum period of five she-camels. Milk samples were collected daily for 60 days from four suckling camels (1-4) and from one animal whose calf died on day 3. Progesterone was determined using the Ovucheck Bovine progesterone kits. The first increase of progesterone level in the five animals occurred on days 28, 26, 21, 24 and 20 respectively. At least two progesterone peaks of 6 +/- 2 SD days' duration occurred during the 60 days. An early one day peak was also noticed in three animals.     

Radioimmunoassay of milk progesterone as a tool for fertility control in smallholder dairy farms

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 post-partum 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.     

The use of computers in dairy herd health program: A review

This review of the literature covers the changes in the approach to veterinary health management that led to the introduction of computerized herd health programs and the various other applications of the computer in the practice of dairy herd medicine. The role that production recording systems, mainframe computers, minicomputers, and microcomputers have played in the evolution of herd health programs are also reviewed.     

The use of milk progesterone profiles for assessing the response to cloprostenol treatment of non-detected oestrus in dairy cattle

Post-partum milk progesterone profiles from 1400 dairy cows were used to identify 296 animals which had ovulated 50 or more days post partum without being observed in oestrus. Of these, 165 cows were left as untreated controls, being inseminated at any observed oestrus after 60 days post partum. Fixed time insemination three and four days after a single cloprostenol injection (74 cows) resulted in a short calving-to-conception interval and a lower culling rate than in control cows, while insemination at observed oestrus after cloprostenol (57 cows) resulted in an even greater improvement in these parameters. The fixed-time insemination group required significantly more services per conception than either of the other groups (P < 0.005). A study of the profiles suggested that not all of the cows had ovulated within four days of injection and that those ovulating later had a greater chance of being observed in oestrus and becoming pregnant if insemination was carried out only at observed oestrus after cloprostenol injection.     

Induced termination of the calving season in a large dairy herd

The calving season of a 550-cow dairy herd was shortened by the induction of premature parturition in 231 cows and heifers, using the synthetic or natural prostaglandins cloprostenol or PGF₂ alpha as the sole treatment, or these agents 8 and 12 days after dexamethasone trimethyl acetate (DTMA), depending on estimated prematurity at the time of first injection. A series of synchronised batch-calvings was produced in the cows, with 85% of the PG group calving within 96 hours of treatment, 97% of the DTMA — 8 days — PG group calving within 48 hours, and 100% of the DTMA — 12 days — PG group calving within 72 hours. PGF₂ alpha was associated with very rapid deliveries and dystocia due to incomplete cervical dilation. Cow and calf survival was high. Eighty-three percent of those mated conceived, 78% of them in the first 8 weeks of mating, despite an incidence of incomplete membrane-expulsion that exceeded 40%. Some conceptions to first service did not progress beyond 6–7 weeks of gestation. In nearly all these cases, the animals conceived at a later service, usually at the first oestrus after expulsion.

The results indicate that acceptable results can be obtained in cows within 2 weeks of term using cloprostenol alone. Treatment regimes that allow a priming dose of depot corticosteroid to precede cloprostenol should be used for terminating less advanced pregnancies.     

检测奶牛乳汁孕酮的免疫生物传感器优化

为了完善已建立的孕酮免疫生物传感器的检测性能,本试验应用碳化二亚胺法将11α-羟基孕酮半琥珀酸和OVA制备成孕酮完全抗原,其浓度达0.6 mg/m L。在此基础上建立了以乳汁为基质的孕酮生物传感器的标准曲线(y=-4.9461x+8.7982,R2=0.993 2),进一步确立了检测乳汁孕酮的线性范围为0.31 ng/m L~50ng/m L,检测限为0.31 ng/m L,灵敏度为0.15 ng/m L,而且孕酮与皮质酮、皮质醇、雄烯二酮的免疫交叉反应较低,表明特异性较好。批内、批间变异系数分别为7.7%和7.5%,回收率为95.8%~115.7%,生物传感器稳定性在4℃保存4 d。该优化的奶牛乳汁孕酮免疫生物传感器的性能参数符合规定的标准,为检测妊娠、乏情和繁殖障碍疾病的奶牛乳汁孕酮含量提供了工具。