Reproductive performance of repeat breeders in dairy herds

The objectives were to characterize repeat breeding in dairy cows, including reproductive performance and risk factors. Data from 613 Holstein Friesian cows in nine dairy herds across Japan were enrolled. A repeat breeder was defined as a cow that did not become pregnant after three inseminations, despite no clinically detectable reproductive disorders. In contrast, cows that became pregnant within three inseminations were considered to have normal fertility. Of the 613 cows, 87.3% eventually became pregnant after repeated AI (maximum calving to conception interval was 435 d). Mean (±SEM) first AI conception rate, days in milk at first AI, calving to conception interval and service per conception were 38.3%, 82 ± 2 d, 125 ± 3 d, and 2.0 ± 0.1 times, respectively. Normal fertility cows (n = 479) required only 114 ± 3 d to conceive and 1.7 ± 0.1 inseminations per pregnancy, whereas repeat breeders (n = 86) required significantly more days to conceive (211 ± 10) and more inseminations per pregnancy (4.7 ± 0.2). Based on survival analysis, it took 94 d after calving for 50% of normal fertility cows to become pregnant, compared to 155 d for repeat breeders. For repeat breeders, 31.4, 50.0, and 58.1% became pregnant within 210, 300, and 435 d after calving, respectively. The risk factors for repeat breeding were parity (relative risk [RR] = 0.809; P = 0.058), resumption of postpartum ovarian cycles (RR = 1.928; P = 0.009), and days in milk at first AI (RR = 0.991; P = 0.039). In conclusion, repeat breeder dairy cows had very poor reproductive performance. Lower parity, abnormal resumption of postpartum ovarian cycles, and shorter days in milk at first AI were risk factors for repeat breeding.     

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.     

Evaluation of a contract breeding management program in Ohio dairy herds: test day summary and economic measures

A field study was conducted to assess the impact of a contract breeding program that was offered by a breeding co-operative and featured tail chalking and daily evaluation of cows for insemination by co-operative technicians; dairy employees no longer handled estrous detection and insemination activities. From early 2002 until mid-2004, herd-level test day summary records related to production and reproduction were obtained for 32 herds identified as well-managed client herds of the breeding co-operative. Using analyses that controlled for other predictors and random herd-level effects, average days to first service were less by 13 days (P=0.0037) and estrous detection rate was greater by 12% (P=0.0011) for program than for non-program herds. Although first service conception rate was slightly less and the program herds used 0.34 more services per conception (P=0.1488) than non-program herds, the program herds averaged 16 fewer days before pregnancy (P=0.028). Test day summary information and representative estimates of feed, milk, and semen prices were used in a spreadsheet-based model to estimate a partial budget annuity value for an average cow in each herd on each test day. Value of an average cow from a contract herd did not significantly differ from a non-contract herd, even though the analyses suggested an economic benefit for the program herds; the modeling did not, however, account for costs of the program implementation. Additional analyses did not find any significant associations between technician and on days to first service, first service conception rate, estrous detection rate, services per conception, or days open.     

Reproductive disorders in dairy cattle: I. Respective influence of herds, seasons, milk yield and parity

This study was performed in two large dairy units (with 130 and 213 calving cows each) during one year. The objectives were to investigate 1) epidemiological patterns of main post-partum reproductive disorders (metritis, post-partum and post-service anestrus, repeat breeding and embryonic death) and 2) the impact of herd, calving season, milk yield and parity on these patterns. Approximately 20% of the cows in both herds were not affected by any of the disorders. Prevalence of metritis was high (32 to 44%) and appeared influenced by the herds' conditions interacting with calving months and milk yield effects. Cyclic post-partum anestrus incidence was also essentially affected by the herd effect with an added seasonal interaction. Other disorders in both herds were also primarily subjected to the seasonal effect. Individual milk yield and parity only marginally affected the epidemiological patterns. We concluded that even in similar environmental conditions, no general patterns of incidence of reproductive disorders can be drawn and that they are essentially dependent on the characteristics of each herd management.     

Antimicrobial use in organic and conventional dairy herds

Use of antimicrobials for food-producing animals is a major public concern due to the risk of antimicrobial resistance. Although dairy production has a relatively low usage of antimicrobials, the potential for further reduction should be explored. The objective of the study was to estimate the current differences in antimicrobial use in Danish organic and conventional dairy herds and to describe the differences between them. Based on data from three different sources, 2604 herds (306 organic and 2298 conventional) were identified for the study. These herds had been either organic or conventional for the entire period from 2015 to 2018. Antimicrobial use was calculated as the treatment incidence in Animal Daily Doses (ADDs)/100 animals/day for three age groups: adult cattle, young stock and calves. For adult cattle, the ratio of median treatment incidence between conventional and organic production ranged from 2.8 : 1 to 3.4 : 1, depending on the specific year. For cows, 25% of the organic herds had a higher treatment incidence than the 25% of conventional herds with the lowest treatment incidence. Antimicrobial use for young stock was low and at a similar level in both the organic and conventional production systems. For calves, the median treatment incidence was 1.2 times higher in conventional herds and 1.6 times higher for the 75th percentile. Analyses of treatment incidence in adult cattle showed an overall decrease from 2015 to 2018 in both organic and conventional herds. The decrease was greater for the conventional herds (0.12 ADD/100 animals/day) compared to the organic herds (0.04 ADD/100 animals/day) over the 4-year period. In addition, herd size was an important risk factor for treatment incidence in conventional herds, increasing by 0.07 ADD/100 animals/day per 100 cows, whereas herd size had a minor influence on the treatment incidence in organic herds. The results of this study demonstrate the large variation in antimicrobial use within both organic and conventional herds, suggesting that further reduction is possible. Furthermore, herd size appears to be a risk factor in conventional herds but not in organic herds – an aspect that should be studied in more detail.     

Reproductive performance of lactating dairy cows treated with cloprostenol at the time of insemination

The effect of intravenous cloprostenol treatment at the time of insemination on reproductive performance was consecutively evaluated in three different subpopulations of high producing lactating dairy cows: Study (1) early postpartum synchronized and fixed-time inseminated (about 50 days in milk) cows (n = 379: 187 control and 192 treated cows); Study (2) presumed high fertility cows first inseminated between 90 and 120 days postpartum (n = 248: 124 control and 124 treated cows); and Study (3) heat stressed repeat breeder cows (n = 183: 93 control and 90 treated cows). Data were analyzed using multiple regression methods. Study 1: Parity (primiparous versus multiparous), milk production, body condition score at AI, insemination season (cool versus warm period) and treatment were included in the analysis as potential factors affecting ovulation, double ovulation, return to estrus, and pregnancy to first AI and to second AI (first AI plus return AI) rates. Logistic regression analysis indicated that the final model for ovulation rate only included the interaction (P = 0.002) between insemination season and treatment. Cloprostenol treatment at insemination led to a 4.2-fold increase in the ovulation rate in cows inseminated during the warm period. There were no significant effects of treatment, parity, milk production, body score or the insemination season on the return to estrus rate. The only variables included in the final logistic model for double ovulation and pregnancy to first AI rates were treatment and season, respectively. Treatment led to a 2.6-fold increase (P = 0.001) in the double ovulation rate, whereas cows inseminated in the warm period were 2.1 times less likely (P = 0.007) to become pregnant at first AI compared to those inseminated in the cool season. The variables included in the final logistic model for the pregnancy rate to second AI were treatment and season. Cloprostenol given at AI increased the risk of pregnancy 1.9 times (P = 0.002), and cows inseminated during the warm season were two times less likely to become pregnant (P = 0.003). No significant interactions were found among these three dependent variables (double ovulation and pregnancy to first and to second AI rates). Study 2: Logistic regression analysis of all the dependent variables: return to estrus, and pregnancy to first and to second AI (first AI plus return to AI) rates indicated no significant effects of treatment, parity, days in milk, milk production or body score at AI. No significant interactions were found. Study 3: The final model for the pregnancy rate only included the interaction between parity (primiparous versus multiparous) and treatment. Days in milk, milk production and insemination number showed no significant effect on pregnancy rate. Cloprostenol treatment at insemination increased the pregnancy rate in primiparous repeat breeder cows (odds ratio: 3.6). The treatment group and parity showed significant (P < 0.0001) interaction. This interaction suggests that cloprostenol treatment of primiparous cows at insemination might enhance pregnancy yet have no effect in multiparous cows. Our findings indicate that cloprostenol administered at insemination promotes ovulation and double ovulation in lactating dairy cows. Cloprostenol treatment showed no benefit in cows with acceptable reproductive performance, suggesting that cloprostenol treatment at AI may only be useful in cows in which stress factors affect ovulation and in repeat breeder cows.     

Reproductive traits in Nubian dairy goats

For 12 months, ten Nubian doe goats were examined daily for oestrus and blood was obtained twice weekly for serum progesterone (P) analysis. Before the onset of regular ovulatory cycles in the autumn, brief increases in serum P were noted. Ovulation without oestrus was associated with the onset of the breeding season in five of 13 instances. Ovarian activity as assessed by corpus luteum (CL) function began in either September or October and ceased in either January or February in nonpregnant does. CL function was absent postpartum until the beginning of the next breeding season. An instance of male pseudohermaphroditism and mucometra is noted.     

Seasonal influences on conception efficiency in Minnesota dairy herds

This study was undertaken to investigate the influence of climatological factors on the conception efficiency of cows in 23 Minnesota dairy herds between March 1982 and March 1985. It was found that year of insemination (P < 0.005), herd (P < 0.005), linear and quadratic terms of days open (P < 0.05), and linear and quadratic terms of minimum temperature (MNT), maximum temperature (MXT) and temperature humidity index (THI) were similarly related to observed monthly variations in first service conception rates. The year of insemination (P < 0.005), herd (P < 0.005), and linear and quadratic terms of MNT, MXT and THI were also related to the variation in overall conception rate. Conception rate declined from April to August and increased from August to January. There was an 11% difference between the month of lowest fertility (August) and the month of highest fertility (November). It can be concluded that climatological factors appear to depress herd fertility in the northern United States as well as in the warmer southern areas. Thus, consideration should be given to strategies which will minimize the impact of the observed fertility depression due to these climatic factors.     

Housing system and herd size interactions in Norwegian dairy herds; associations with performance and disease incidence

Background  

According to the Norwegian animal welfare regulations, it has been forbidden to build new tie-stall barns since the end of 2004. Previous studies have shown that cow performance and health differ between housing systems. The interaction between housing system and herd size with respect to performance and disease incidence has not been evaluated.     

Relationships between milk mid-IR predicted gastro-enteric methane production and the technical and financial performance of commercial dairy herds

Considering economic and environmental issues is important in ensuring the sustainability of dairy farms. The objective of this study was to investigate univariate relationships between lactating dairy cow gastro-enteric methane (CH₄) production predicted from milk mid-IR (MIR) spectra and technico-economic variables by the use of large scale and on-farm data. A total of 525 697 individual CH₄ predictions from milk MIR spectra (MIR-CH₄ (g/day)) of milk samples collected on 206 farms during the Walloon milk recording scheme were used to create a MIR-CH₄ prediction for each herd and year (HYMIR-CH₄). These predictions were merged with dairy herd accounting data. This allowed a simultaneous study of HYMIR-CH₄ and 42 technical and economic variables for 1024 herd and year records from 2007 to 2014. Pearson correlation coefficients (r) were used to assess significant relationships (P<0.05). Low HYMIR-CH₄ was significantly associated with, amongst others, lower fat and protein corrected milk (FPCM) yield (r=0.18), lower milk fat and protein content (r=0.38 and 0.33, respectively), lower quantity of milk produced from forages (r=0.12) and suboptimal reproduction and health performance (e.g. longer calving interval (r=−0.21) and higher culling rate (r=−0.15)). Concerning economic results, low HYMIR-CH₄ was significantly associated with lower gross margin per cow (r=0.19) and per litre FPCM (r=0.09). To conclude, this study suggested that low lactating dairy cow gastro-enteric CH₄ production tended to be associated with more extensive or suboptimal management practices, which could lead to lower profitability. The observed low correlations suggest complex interactions between variables due to the use of on-farm data with large variability in technical and management practices.     

Factors affecting the fertility of high producing dairy herds in northeastern Spain

Infertility has been often correlated to a rising milk yield in high producing dairy cattle. The aim of the present study was to evaluate, using logistic regression procedures, the effects of several management indicators on the fertility of four dairy herds in northeastern Spain. Data derived from 10,965 artificial insemination (AI). The factors examined were: herd, milking frequency (three versus two milkings per day), lactation number, previous twinning and disorders such as placenta retention and pyometra, milk production at AI, the inseminating bull, season (warm versus cool period) and year effects, AI technician and repeat breeding syndrome (cows undergoing four or more AI). Our findings indicated no effects on fertility of the herd, year of AI, previous twining, placenta retention and pyometra and milk production at AI. Based on the odds ratios, the likelihood of pregnancy decreased: in cows milked three times per day (by a factor of 0.62); for each one unit increase in lactation number (by a factor of 0.92); for inseminations performed during the warm period (by a factor of 0.67); in repeat breeder cows (by a factor of 0.73); and when 3 of the 45 inseminating bulls included in the study were used (by factors of 0.35, 0.43 and 0.44, respectively). Of the 13 AI technicians participating in the study, 3 were related to a fertility rate improved by odds ratios of 1.86, 1.84 and 1.30, respectively, whereas 2 technicians gave rise to fertility rates reduced by odds ratios of 0.64 and 0.49, respectively. Under our study conditions, management practices were able to compensate for the effects of previous twining and reproductive disorders such as placenta retention and pyometra. However, fertility was significantly affected by the factors milking frequency, AI technician, inseminating bull, repeat breeding syndrome, lactation number and AI season.     

Streptomyces genetics in the 1990s

World Journal of Microbiology and Biotechnology - The 1980s were a fertile time for research inStreptomyces molecular genetics. Many important questions and possibilities have been raised. In the...     

Reproductive performance of dairy cows with ovarian cysts after different GnRH and cloprostenol treatments

Cystic ovarian disease is an important cause of reproductive failure and economic loss for the dairy industry. This report describes two consecutive studies. The objective of the first was to evaluate the response of cows with ovarian cysts to two therapeutic treatments. In the second study, we compared the effectiveness of the best treatment established in Study 1 with that of the Ovsynch protocol. For Study 1, cows were considered to have an ovarian cyst if it was possible to observe a single follicular structure with a follicular antrum diameter > 25 min in the absence of a corpus luteum in three ultrasonographic examinations performed at 7 days intervals. At diagnosis (Day 0), cows were assigned to one of two treatment groups. Cows in Group GnRH/CLP (n = 31) were treated with 100 microg GnRH i.m. and 500 microg cloprostenol (CLP) i.m. on Day 14. Cows in Group GnRH-CLP/CLP(n = 32) were treated with 100 microg GnRH i.m. plus 500 microg CLP i.m. on Day 0, and 500 microg CLP i.m. on Day 14. The animals were inseminated at observed estrus and monitored weekly by ultrasonography for 4 weeks or until Al. Cows in the GnRH-CLP/CLP group showed a lower cystic persistence rate (15.6% < 45.2%; P = 0.01); a higher estrus detection rate (84.4% > 41.9%; P < 0.0001); a higher ovulation rate (75% versus 32.3%; P < 0.0001) and a higher early response rate (31% > 3%; P = 0.02) than those in the GnRH/CLP group. For the second study, 128 cows with ovarian cysts were randomly assigned to one of two treatment groups: cows in Group Ovsynch (n = 64) were treated with 100 microg GnRH i.m. on Day 0, 500 microg CLP on Day 7, and 100 microm GnRH i.m. 36 h later. Cows in this group were inseminated 24 h after the second GnRH dose (Ovsynch protocol). Cows in Group GnRH-CLP/CLP/GnRH (n = 64)were treated as those in the GnRH-CLP/CLP group of Study 1 but received GnRH 32 h after the second CLP treatment and were inseminated 24 h after this. A further group of cows without ovarian cysts inseminated at natural estrus served as the Group Control (n = 64). Cows in the GnRH-CLP/CLP/ GnRH group showed a lower cystic persistence rate (10.9% < 46.9%; P < 0.0001); higher ovulation rate (79.7% > 17.2%; P < 0.0001); higher return to estrus rate (34.3% > 12.5%; P < 0.01) and higher pregnancy rate (28.1% > 3.1%; P < 0.01) than those in Ovsynch; and a similar pregnancy rate (28.1% versus 35.9%) to Control cows. These findings indicate that lactating cows with ovarian cysts can be successfully synchronized and time inseminated using a protocol that combines GnRH and CLP, starting treatment by simultaneously administering both products. This protocol also allows the insemination of cows showing estrus within the first week of treatment. Ovarian cysts were less responsive when treatment was started with GnRH alone.