A health program for commercial dairy herds. 3. Changes in reproductive performance

Managerial practices and factors influencing reproductive performance of dairy cows in urban/peri-urban areas of Kampala and Gulu, Uganda

BACKGROUND

Urban/peri-urban dairy production and sales has evolved as an adjustment to cope with food security and economic needs for urban dwellers in low-income countries and created an opportunity to transform from subsistence rural lifestyles of dairy farming to commercial engagement in towns. However, urban/peri-urban dairy farms differ in challenges from rural dairy farms and reproduction is important and critical for assuring sustainable economic output in both environments. Here we recorded for the first time differences between two geographically and economically different cities corresponding to different settings within the same country in managerial factors influencing reproductive performance in urban/peri-urban dairy cowherds.

RESULTS

The urban/peri-urban dairy farmers in the capital Kampala were more often male (P = 0.002) and commercialized (P = 0.0025), more experienced (P = 0.0001) and practiced zero-grazing more often (P = 0.05) than in the regional municipality Gulu. Also, the milk production per herd and cow (P = 0.0005) and calving rate were (P = 0.0001) higher in Kampala and artificial insemination was more commonly (P = 0.002) used than in Gulu. There was no difference in abortion nor neonatal mortality rate between the two locations. Overall, calving rates were higher (P = 0.0003) in smaller (≤3 dairy cows) and open grazing (P = 0.003) herds. Abortion rates were higher among dairy herds practicing late (≥5 months) (P = 0.003) calf weaning and in herds with commercial purposes (P = 0.0001). Neonatal calf mortality was lower (P = 0.01) in small herds.

CONCLUSION

The study showed significant differences between Kampala and Gulu in reproductive performance and related husbandry factors for cows in the urban/peri-urban dairy farming systems. For several reproductive performance traits we found associations with husbandry and production traits, which should be taken into account when providing advice to the urban and peri-urban dairy farmers in the tropics.

Reproductive performance of dairy cows following treatment with cloprostenol 26 and/or 40 days postpartum: a field trial

One hundred and seventy Holstein Friesian cows were randomly assigned to receive either 500 ug cloprostenol or saline placebo on Day 26 postpartum followed by 500 ug cloprostenol or saline on Day 40 postpartum. Four treatment groups were formed: Group 1-saline (Day 26)/saline (Day 40); Group 2-cloprostenol/(Day 26) saline (Day 40); Group 3-saline (Day 26)/cloprostenol (Day 40); Group 4-cloprostenol (Day 26)/cloprostenol (Day 40). Double blind techniques were used in administering treatments and in assessing the response to treatment. Palpation of the reproductive tract per tectum and uterine biopsies were performed on 92 cows prior to each treatment at Day 26 and Day 40 postpartum. Progesterone concentrations were determined on milk samples collected prior to treatment. There were no significant differences among treatment groups with respect to services per conception, number of heats detected before first service and culling for infertility. Cloprostenol treatment at Day 26 appeared to delay the first estrus, but it reduced the number of days to conception after the first service. Cows receiving cloprostenol at Days 26 and/or 40 had a decreased calving-to-conception interval compared to controls (P=0.01). Sequential therapy with two doses of cloprostenol resulted in slightly better reproductive performance than either treatment on Day 26 or 40 alone. Treatment with cloprostenol resulted in a decrease in the subsequent incidence of pyometra (P<0.05). It is concluded that in the herd studied, cloprostenol therapy at Day 26 and/or 40 postpartum was beneficial to reproductive performance. Although it was anticipated that cloprostenol would be more effective in cows with elevated progesterone levels, the opposite was observed at the Day 26 cloprostenol treatment. Uterine biopsy at Days 26 and/or 40 had a detrimental effect on subsequent reproductive performance.

Advances in bovine theriogenology in New Zealand. 2. Breeding management and technologies for improved reproduction

The importance of submission rates (SR) on conception patterns in dairy herds during a short artificial breeding (AB) programme was first reported in 1973. Subsequent research has focussed on achieving 3-week SRs of 90% through improved detection of oestrus utilising tailpainting and vasectomised bulls fitted with chin-ball harnesses. Despite nutritional limitations of spring pasture as a sole diet, conception rates to first insemination of 65% have been recorded in cycling cows in many trials. Anovulatory anoestrus (AA) has become a major factor compromising SRs as well as reducing average conception rates and herd in-calf rates by 4-7 weeks after the planned start of mating (PSM). Whole herd synchronisation programmes have been developed but not widely used on dairy cows and have had only limited use on dairy heifers, despite a focus on concentrated conception patterns. The related technologies have become most commonly used to increase the SR of AA cows. Extreme variation in the weekly demand for processed semen in seasonally-intensive AB programmes has been accommodated by the development of a unique semen diluent, Caprogen. Its use has allowed sperm to be temporarily stored without freezing and used at dose rates of 1 million sperm/insemination. Sire variation with this form of semen processing is lower than with deep frozen semen. The greater use of production genes derived from Holstein-Friesian sires of North American origin in most AB programmes has left progeny with reduced reproductive performance. This effect has been greater than that associated with the increased productivity of dairy cows achieved through continued use of semen from intensively selected groups of progeny tested sires.

Factors affecting reproductive performance in Ontario dairy herds

Data were collected on reproductive, health and production events in 45 dairy herds in southwestern and eastern Ontario, Canada, from July 1990 to July 1993. Mean and median days in milk at first estrus, at first service, and at conception were 85.1 and 83.9, 94.0 and 88.9, and 126.3 and 115.5 d, respectively. The mean estrus detection rate was 48.3%, with a minimum of 28.4% and a maximum of 64.2%. The mean overall conception rate was 46.7%, with a minimum of 29.8% and a maximum of 70.7%. The most commonly used used therapeutic agents were GnRH (11.5% lactational incidence risk) and PG (13.1% lactational incidence risk). Estrus management accounted for the largest portion of PG use in the herds studied (69.4%). Results of a two sample t-test indicated no significant difference in reproductive performance among herds housed in free-stall compared with those housed in tie-stall barns. Multivariate linear regression models of 3 reproductive performance measures indicated that cows with ovarian cysts and/or increased peak milk production had significantly longer calving-to-first estrus and calving-to-conception intervals as well as lower conception rates than average producing cows without cysts. Cows with metritis were found to have significantly shorter calving-to-conception intervals but no detectable difference in conception rate or calving-to-first estrus interval than their herdmates. As lactation number increased reproductive performance improved. Cows that were observed in estrus earlier conceived earlier. Animals receiving uterine infusions had significantly longer calving-to-conception intervals and lower conception rates than their herdmates. There was no detectable difference in reproductive performance for cows treated with GnRH or PG compared with the nontreated cows. An increased estrus detection rate was associated with shorter calving-to-conception intervals and lower conception rates. Based on the range of performance in the study herds, the factors with the greatest potential influence on calving-to-conception interval in the average herd were the estrus detection rate and conception rate.

Production and reproductive responses to use of DairyMAN: a management information system for New Zealand dairy herds

To assess the benefits of on-farm use of a computerized management information system (DairyMAN, Department of Veterinary Clinical Science, Massey University, Palmerston North, New Zealand) on seasonally calving herds of New Zealand, data for 144 herds using this system were compared with a stratified random sample of 294 herds using only the centralized National Dairy Database system during the season 1993 to 1994. Demographic, reproductive performance, and milk yield indices were compared. Herds using DairyMAN had superior reproductive outcomes, measured as a higher percentage (+8.4%) of cows calving during the desired seasonal period (critical in this seasonal system) and a higher percentage of cows (+9.7%) mated at the optimal time to achieve a concentrated calving in the following year. Multiple analysis of covariance was used to differentiate effects. The superior performance was not associated with differences in some of the more commonly used reproductive indices (efficiency of estrus detection, first service nonreturn rate, and pregnancy rate), but the data used in the study do not accurately reflect true performance. Herds using DairyMAN had more information on breeding performance because pregnancy data were available and natural breedings were recorded for a longer period. With cows of equivalent genetic merit, herds using DairyMAN produced more milk (+1.2 L/d per cow) indicating that users achieved better management of the herd through improved attention to managerial details. This improved production was associated with the adoption of DairyMAN but is not shown by this study to be a direct consequence of it. DairyMAN user herds were larger (245 cows) than were herds not using the system (181 cows), but this difference did not significantly affect the various outcomes measured.

A case-control study to identify farm factors affecting fertility of dairy herds: univariate description of factors

OBJECTIVE

To identify farm factors which were associated with reproductive performance in dairy herds in New South Wales.

PROCEDURE

A survey was administered by face to face interview to examine the responses of producers drawn from 757 herds, which used the New South Wales Agriculture Department Dairy Herd Improvement scheme. A case-control approach was used to select a total of 126 herds from the first (top group-cases) and fourth quartiles (low group-controls) for intercalving interval.

RESULTS

We found that the estimated interval from calving to first mating was significantly different between group (P = 0.03) and that the groups significantly differed in both their target for interval to first mating (P = 0.02) and their perceived optimum time for first mating (P = 0.04). Other factors associated with a longer intercalving interval included, use of embryo transfer programs (P = 0.08), younger managers (P = 0.02), fewer breedings per day (P = 0.01), a greater number of people detecting heats (P = 0.07), but less hours spent detecting heats while handling the cows (P = 0.11), and a failure to vaccinate bulls for campylobacteriosis (P = 0.14).

CONCLUSIONS

Managers of herds with poorer reproductive performance did not intend to mate cattle as soon after calving as managers with better reproductive performance, were not as active in seeking veterinary advice on reproduction, and were attempting to treat reproductive diseases and disorders themselves.

The frequency of endemic fetal loss in dairy cattle: A review

Estimates of the frequency of endemic fetal loss range from 0.4 to 10.6%, a 26-fold difference, in 26 studies of dairy herds over 5 decades. Sources of this difference include breed, geographic, study population, case definition and procedural differences. The definition of fetal loss was inconsistent among the studies and was often not clearly stated. Twelve of the studies cited only visually observed losses, while the remainder reported losses of all known pregnancies but using different gestational at-risk periods. Definitions of the resulting frequency measure and methods of computation varied widely among the studies. Fetal loss frequencies have been reported as ratios, proportions, incidence rates and cumulative incidence rates. Denominators used in frequency calculations have included the number of pregnant cows, number of cows in the breeding herd, number of cows that calved before or after the risk period and number of calves born. These procedural differences make comparisons among studies and an overall estimate of an expected frequency of endemic fetal loss in dairy cattle difficult at best. Procedural and definition differences aside, the median frequency of fetal loss from studies enumerating only observed abortions was 1.95% and from the studies that included both observed and unobserved abortions 6.5%. Based on this difference, approximately only 30% of endemic fetal losses are observed visually.

Reproductive performance of dairy cows following treatment with fenprostalene, dinoprost, or cloprostenol between 24 and 31 Days post partum: A field trial

Three hundred and one Holstein cows (n=301), calving at a commercial free-stall dairy farm, were randomly assigned to 1 of 3 prostaglandin treatment groups or a placebo group. The placebos were packaged 3 ways to mimic the 3 commercial prostaglandin preparations. Group 1 received 1 mg fenprostalene and 1.6 mg oxytetracycline; Group 2 received the fenprostalene placebo (2 ml polyethylene glycol and 1.6 mg oxytetracycline); while Group 3 was given 25 mg dinoprost. Group 4, the dinoprost placebo received 5 ml saline; Group 5 received 500 microg cloprostenol; and Group 6 the cloprostenol placebo received 2 ml saline. The treatments were administered between Days 24 and 31 post partum. Double blind techniques were used in administering treatments and in assessing the response to treatment. There were no significant differences among treatment groups with respect to incidence of retained fetal membranes, endometritis, pyometra, anestrus, number of services per pregnancy, calving-to-first estrus interval, services per conception, number of prostaglandin treatments other than those administered between Days 24 and 31 post partum, the percentage culled for reproductive reasons and all factors combined. Cows receiving fenprostalene, dinoprost or cloprostenol had a decreased calving-to-conception interval compared with that of the controls (P = 0.05). It is concluded that, in the herd studied, treatment with any of the 3 commercially available prostaglandin products between Days 24 and 31 post partum was beneficial for reproductive performance.

A cross-sectional study of bluetongue virus and Mycoplasma bovis infections in dairy cattle: II. The association between a positive antibody response and reproduction performance

In a cross-sectional study to determine the possible relationship between a positive antibody test to bluetongue virus (BTV) or Mycoplasma bovis infections and reproductive performance of dairy cows, data were collected on 572 California dairy cows during December 1986 for analysis. Serum samples were tested using an enzyme-linked immunosorbent assay (ELISA). Data on reproduction variables were extracted from the individual cow sheets of the California Dairy Herd Improvement Association records and interfaced with the serological results for analysis. Similar data analyses for both BTV and M. bovis were performed to identify and quantitatively assess the association of the reproduction variables and each agent. These associations were evaluated unconditionally using the chi 2 for categorical variables and Student's t-test for continuous variables. Logistic regression analysis was used to determine if reproduction variables with significant unconditional associations remained significant when adjusted for the effects of possible confounding factors. Both the BTV and M. bovis ELISA antibody titres indicated exposure to the agents. The results of the multiple logistic regression analyses indicated that cows seropositive for BTV were significantly older at first calving (p less than 0.03). For M. bovis, seropositive cows were more likely to have longer intervals from calving to last service and longer intervals from calving to pregnancy diagnosis than seronegative cows (p less than 0.05). The other reproduction variables examined were not significantly associated with ELISA seropositivity.

Prolonged service intervals in cattle

A trial based on progesterone radioimmunoassay of milk samples is described. Samples from 2274 cows in 14 herds were collected on the day of insemination and 7, 23 and 30 days later, unless a return to service occurred before the designated sample date. Two additional samples were collected from cows which returned to service more than 35 days after the first service, one on the day of the return and another seven days later. All six samples from these cows were assayed for progesterone concentration. Late returns, defined as returns to oestrus 36 or more days after mating, occurred in 8.6% of the cows. Milk progesterone assay results indicate that of these apparently late-returning cows, 55.9% suffered a loss of the conceptus, 22.1% had not been detected in oestrus around 21 days after first insemination, 11.8% were in anoestrus at insemination, 5.6% conceived to the insemination and were pregnant when thought to have had a late return, 2.6% were in prooestrus or dioestrus at insemination and 2.1% went into anoestrus after an oestrus insemination. The average prevalence of late returns after the 35th day (8.6%) and the estimated incidence of losses of concepta (4.8%) are lower than those reported in comparable studies elsewhere. Although many of the late-return cows were mated again and conceived, this syndrome nevertheless contributes significantly to the wastage rate, at least in New Zealand dairy herds with their strictly seasonal calving pattern. The implications of these findings are discussed and recommendations for their prevention are made where appropriate.

A three year herd health and management program on thirty Dutch dairy farms. III. Economic evaluation of fertility control

Fertility control was part of a herd health and management program on thirty dairy farms in the province of Overijssel. A comparable control group of thirty-one farms was available. After two years of application of the program the improvement in income feedcosts margin per cow on the program farms exceeded that on control farms by Dfl. 176. Within the large variation in income between the farms it was not possible to accurately distinguish the effects of the different aspects of the program, despite the use of detailed techniques such as Factor Analysis: thus another approach to determine the income effect of fertility control was necessary. The total loss per farm due to sub-optimal fertility was determined, using calving interval data, forced replacement data and norm-loss rates. From computation of this loss on program and control farms, the income effect of fertility control was deduced. Excluding the cost of the program, a significant (P less than 0.01) positive effect of fertility control on the total calculated loss due to sub-optimal fertility was determined (average Dfl. 25.50 per cow, or about Dfl. 1,700 per farm, after two years of program application). This income effect differed considerably between farms with an initial good or poor situation regarding fertility. The program contributed more to the improvement of insufficient or moderate fertility than to the prevention of a deterioration in herds with excellent fertility, although on the latter farms the total program had a considerable positive effect.

Postpartum ovarian function of dairy cows in a tropical environment

Intervals from parturition to first estrus and to the first three ovulations were studied in 25 Holstein and 31 Jamaica Hope cows in Jamaica. Casual observations for signs of estrus were supplemented by twice nightly observation periods. Samples of blood plasma were obtained twice weekly from all cows and assayed for progesterone. The progesterone profile for each cow was used to determine when ovulations occurred. Intervals and standard deviations from parturition to first, second, and third ovulations were 19.8 +/- 8.8, 39.4 +/- 9.0, and 58.6 +/- 9.2 days for Holsteins, which were shorter than the same intervals for Jamaica Hope cows (28.7 +/- 15.6, 46.9 +/- 13.6, and 66.3 +/- 12.6 days). Intervals from parturition to first detected estrus were 46.0 +/- 21.4 days for Holsteins and 45.5 +/- 18.7 days for Jamaica Hopes. There were no significant differences between seasons of calving in intervals to ovulations or in intervals to first detected estrus. Percentages of cows detected in estrus at the first, second, and third ovulations were 19, 61.9, and 57.8% for Holsteins and 43.3, 55.2, and 73.1% for Jamaica Hopes. Holstein cows kept in a tropical environment are capable of returning to a cycling, rebreedable state and of showing detectable signs of estrus as soon after calving as can be expected reasonably.

Effect of adding superphosphate to the drinking water on the fertility of dairy cows

Mean serum inorganic phosphorus concentrations of cows in an infertile dairy herd of 170 cows in the Hunter Valley increased from less than 4.5 mg/100 ml to greater than 5.8 mg/100 ml after defluorinated superphosphate was added to their drinking water at the rate of 2.5 kg/450 1 once weekly from September, 1976. The first service pregnancy rate increased from 36.5% to 63.2%, the mean calving to conception interval decreased from 109 days to 85 days and the number of cows culled each year for infertility fell from 15 to 5. The pasture fed to the milking cows contained on average greater than 17% crude protein, greater than or equal to 0.39% phosphorus, greater than or equal to 9 ppm copper and 38--46 ppm manganese according to the dominant species. The Ca/P ratio ranged from 2 to 5.5:1. Of these, only the Ca/P ratio and the manganese concentrations appeared to be abnormal.