Journal of Reproduction and Development
Online ISSN : 1348-4400
Print ISSN : 0916-8818
ISSN-L : 0916-8818
Volume 56, Issue S
Supplement
Displaying 1-10 of 10 articles from this issue
  • Stephen LEBLANC
    2010 Volume 56 Issue S Pages S1-S7
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    There is much debate about possible antagonism between high milk production and reproductive performance. This paper reviews methods of measuring reproductive performance and the association of the level of milk production with pregnancy rate at the herd and individual levels. The main question is whether fertility (the capacity for reproductive function and successful pregnancy) of dairy cows has in fact declined, as opposed to the success of management systems and people at meeting the metabolic, nutritional, housing, and social needs of increasingly productive animals but with no less inherent capacity to achieve and maintain pregnancy; and if fertility really has diminished, the extent to which this decline is caused by increased milk production. There is no doubt that production per cow has increased, but it is unclear how much of this increase can explain the apparent decrease in fertility. It is important to separate the biology of reproductive function from the effects of economically based management decisions about culling and continuation of breeding. Most traditionally-used measures of reproductive performance (calving interval, conception rate, non-return rate) are incomplete or severely biased outcome measures. Both herd and cow-level data should include as much information as possible on confounders of the relationship of production with reproduction. Population or herd-level data should not be used to make inferences about individual-level associations. Considering the quality of data and analytic methods in the published literature, it is not clear if there is any association between higher milk yield and the probability and timing of pregnancy, either among cows at various levels of production in a population at one time, or with increasing production over time.
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  • Nadav GALON, Yoel ZERON, Ephraim EZRA
    2010 Volume 56 Issue S Pages S8-S14
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    The objectives of this review are to describe the reproductive parameters monitored in Israeli dairy herds and to evaluate their changes in recent years. Eighty percent of the cows and 70% of the farms use the Israel Cattle Breeders' Association Herdbook and about 50% of them use pedometry systems. Intensive herd medicine is practiced in 80% of the herds by Hachaklait Veterinary Services Ltd. Herd-health reports monitor calving, production and reproduction. Causal analysis explains the effects and interactions of various risk factors involved. The average of 305 days of milk production per cow increased between 2004 and 2008 from 11,200 to 11,903 kg. At the same time the first A.I. conception rate (C.R) dropped from 43.0 to 40.7% and from 35.6 to 30.5% in primiparous cows (PC) and multiparous cows (MC), respectively. The waiting period (WP) was shortened from 106.2 to 93.4 days in PC and from 99.9 to 87.3 days in MC. The undetected heat rate per herd increased from 30.3 to 38.9% and from 33.9 to 43.9% in PC and MC, respectively. The average of days open per herd dropped from 127 to 118.4 and from 127.5 to 120.5 in PC and MC, respectively. The rate of cows open by 150 days in lactation dropped from 42% (± 10.2) to 34.2% (± 8.1) and 47.1% (± 8.8) to 39.5% (± 7.1) in PC and MC, respectively. The ratio between summer inseminations and winter inseminations increased from 0.81 to 1.04 from 2000 to 2008. The calving interval (CI) average fluctuated around 424.5 (± 2.0) days and 417.5 (± 1.7) days in PC and MC, respectively. The average duration of the dry period in 2008 was 60.7 (± 4.7, 47-72) days. From 2004 to 2008, the average herd rate of endometritis increased from 38.1 to 46.0% and from 25.5 to 30.1% in PC and MC, respectively. The milk fat to protein ratio in the first test day of lactation has remained steady during the past 5 years. Genetic trends in the breeding values of fertility and milk showed consistent improvement from 2000 to 2006. Conclusions: In recent years there has been a small decline in some reproductive parameters, while at the same time others have remained unchanged. The farmer's economical viewpoint and management practices have contributed to the changes.
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  • Anne BARBAT, Pascale Le MÉZEC, Vincent DUCROCQ, Sophie MATTALIA ...
    2010 Volume 56 Issue S Pages S15-S21
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    In most countries where genetic selection for milk production has been conducted, a continuous degradation of reproductive performances has been observed in dairy cattle. This paper describes the phenotypic evolution of fertility traits in France for the main 3 dairy breeds and the different actions undertaken to counteract this unfavourable evolution of reproductive performance. In 2001, functional traits (including conception rate as a fertility trait) have been included into the French total merit index ISU, to take these traits into account in the selection objective. In addition, a marker-assisted selection (MAS) program has been developed since 2001. Through this approach, a set of QTL related to fertility traits were identified using the phenotypic information for fertility collected on a national basis. Fine mapping of these QTL let to their introduction in 2008 in genomic evaluation and the routine selection for fertility traits in breeding schemes. This approach will evolve in the near future through the inclusion of results of several genomic research programs that were conducted either in station or under field conditions aiming at identifying genes and pathways controlling cattle fertility (based on genomics, transcriptomics and proteomics) and at enhancing phenotyping for reproductive performance. The paper describes the general approach behind these evolutions, the expected benefits of genomic selection and first results. Information on the potential use of reproductive technologies that may improve the efficiency of multiple trait genomic selection are also presented.
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  • Ric R. GRUMMER, Milo C. WILTBANK, Paul M. FRICKE, Rick D. WATTERS, Noe ...
    2010 Volume 56 Issue S Pages S22-S28
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    Fertility of dairy cows has decreased for the past several decades. Measures of energy balance (EB; e.g. change in EB, EB nadir, cumulative negative EB, or duration of negative EB) are related to reproductive performance. Our research group has concluded that modification of diets fed during the dry or transition period are unlikely to have significant effects on postpartum EB and fertility. Rather, more radical alterations in dairy management are needed if energy status of postpartum cows is to be improved. We have examined the potential to alter EB by shortening or eliminating the dry period. In an initial study, the effects of a 56, 28, and 0 d dry period on ovarian dynamics and reproductive performance of dairy cows were examined. Postpartum EB was improved by reducing the dry period; however, only significantly for the 0 d dry period. Cows on the 0 d dry period did not experience negative EB. Improvements in EB were a reflection of lower milk production and greater feed intake. Consistent with the improvements in EB, time to first ovulation and first service, first service conception rate, services per conception, and days open were all improved by reduction of dry period length. Because small animal numbers were used in the study, a second study was conducted on a commercial dairy with many more animals to determine if results from the initial trial could be duplicated. A comparison was made between a 55 and 34 d dry period. Shortening the dry period resulted in fewer days to first ovulation, fewer days open, and a greater percentage of cows pregnant at 150 days in milk, although the improvements in the latter two variables were only significant for cows in their third or greater lactation. A current study is being performed in a large commercial dairy to examine the effects of eliminating the dry period on reproduction utilizing a large commercial dairy.
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  • Stephen LEBLANC
    2010 Volume 56 Issue S Pages S29-S35
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    This paper reviews the importance of energy metabolism in transition dairy cows, its associations with disease and reproduction, and strategies for monitoring cows under field conditions during this critical time. Essentially all dairy cattle experience a period of insulin resistance, reduced feed intake, negative energy balance, hypocalcemia, reduced immune function, and bacterial contamination of the uterus soon before, or in the weeks after calving. One-third of dairy cows may be affected by some form of metabolic or infectious disease in early lactation. Routine, proactive actions, observations, or analysis are intended to accurately and efficiently provide early detection of problems, to provide an opportunity for investigation and intervention in order to limit the consequences and costs of health problems and reduced animal performance or welfare. Methods of early detection include monitoring of disease and culling records, feed intake, milk production, body condition, and simple metabolic tests. Methods, strategies, and interpretation of measurement of peripartum concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) as indicators of aspects of energy status and disease risk are reviewed. High NEFA (> 0.4 mmol/l) in the last 7 to 10 days before expected calving is associated with increased risk of displaced abomasum (DA), retained placenta, culling before 60 days in milk, and less milk production in the first 4 months of lactation. Subclinical ketosis (serum BHB > 1200 to 1400 μmol/l) in the first or second week after calving is associated with increased risk of DA, metritis, clinical ketosis, endometritis, prolonged postpartum anovulation, increased severity of mastitis, and lower milk production in early lactation. There are several validated and practical tools for cow-side measurement of ketosis.
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  • Israel FLAMENBAUM, Nadav GALON
    2010 Volume 56 Issue S Pages S36-S41
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    Israel has about 100,000 dairy cows mostly all of Israeli-Holstein-breed, kept in close to 1,000 dairy farms. Most farms are distributed along the Mediterranean Sea coast and in the hot internal valleys. According to the Israeli Herd book the average annual milk production, per cow in 2008 was 11,460 kg, with 3.7% fat and 3.2% protein. Israel's climate is considered "subtropical dry" or Mediterranean, characterized by warm and dry summer with day temperatures above 30 C and relative humidity ranging from 50 to 90%. Climatic limitations brought dairy farmers to develop and implement new technologies and management practices that would enable high milk production and reproduction in summers. In the last three decades the Ministry of Agriculture research units, the extension service and dairy farmers conducted a series of trials and surveys in order to develop an efficient cooling system that will obtain and maintain high milk yield and good reproduction during the hot and humid summer. The cooling system commonly used in Israel is based on a combination of frequent direct watering of the cows, followed by forced ventilation air blowing onto the cows. The system was developed in Israel nearly 30 years ago. A typical cycle is five minutes long and consists of 30 sec of watering followed by 4.5 min of forced ventilation. Providing the cows with 5-7 cooling sessions per day, 30-45 min each, allowed cows, producing 25-30 kg of milk per day to maintain their body temperature below 39.0 C, throughout the day time, on a typical Israeli summer day. At the same time, non-cooled cows had high body temperatures (above 39.5 C), during some part of the daytime and returned to normal body temperatures (below 39.0 C), only for a few hours late at night. In an experiment conducted in 1985-86, conception rate (CR) of cows, cooled as described above, was significantly higher than of non-cooled cows (59 vs. 17% and 57 vs. 17%), for first insemination and for all inseminations, respectively. Pregnancy rate (the amount of pregnant cows out of the eligible cows in the herd) calculated for 90, 120 and 150 days after calving differed significantly between the groups, (44, 59 and 73% vs., 5, 11 and 11%), in cooled and non-cooled cows, respectively. CR and pregnancy rates obtained in intensively cooled herds in this experiment were similar to those obtained during the winter of that year, in commercial dairy farms in Israel. Differently from the results described above, when cows in summer were intensively cooled, only for a period of 2 days before and 8 days after A.I, CR failed to improve (31 and 36%), in cooled and non-cooled cows, respectively. These results offer a conclusion that cows must be intensively cooled and must maintain normal body temperatures during the entire day and during the whole summer.
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  • Keith L. MACMILLAN
    2010 Volume 56 Issue S Pages S42-S47
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    Synchronization programs have become standard components in the current breeding management of cows in the dairy herds of most dairy industries. Many are based on protocols that allow timed inseminations (TAI) so as to circumvent the practical difficulties associated with estrus detection. These difficulties are exacerbated in modern herds of high producing cows either because of increasing herd size in which individual animal monitoring is difficult and often subjective, or because small intensively managed herds are milked in robotic systems that minimize animal: staff interactions. Additional reasons arise from high producing cows having less obvious symptoms of estrus, partly because of housing systems combined with intensive feeding and milking, partly because of higher metabolic clearance rates of reproductive hormones like estradiol and partly because of the increasing prevalence of prolonged post-partum anestrus and reproductive tract pathology. The most recently developed programs include protocols for re-synchronization following first or subsequent inseminations. These re-synchronization protocols may involve selected forms of hormonal intervention during the diestrous and pro-estrous periods following TAI, or following pregnancy diagnosis by ultrasound from 28 days after TAI. The latter form of re-synchronization has become increasingly important with the recognition that late embryonic/early foetal death has become a major factor compromising the reproductive performance of high producing Holstein cows in many dairy industries. Although cows detected in estrus without any hormonal treatment before insemination have higher conception rates than those inseminated following synchronization and TAI, the low detection rates combined with embryonic death means that intervals from calving to conception (days open) are usually less when synchronization programs have been successfully implemented. One of the significant factors affecting a program's success is the compliance rate that may sometimes be less than 70%. Almost all programs involve strategically timed injections of prostaglandin F2α (PGF) and gonadotropin releasing hormone (GnRH). Injections of an estradiol ester and progesterone supplementation per vaginum may be included in some programs. The basic program is the "Ovsynch" regimen. Numerous variations have been tested and developed. Many involve increasingly complex protocols that increase the risk of non-compliance, none has consistently achieved conception rates that exceed 40% and few have reduced the incidence of embryonic death. These synchronization programs are the best that are currently available. They have not been able to overcome the consequences of lowered fertility associated with high levels of milk yield, forms of nutrition and environmental factors like heat stress that have profound effects on the physiology and metabolism of the high producing dairy cow.
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  • Nadav GALON
    2010 Volume 56 Issue S Pages S48-S52
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    The objectives of this review are to describe the use of pedometry on commercial dairy farms in Israel, to evaluate its efficiency in heat detection and to describe a clinical trial comparing between pedometry and the Ovsynch technique. Pedometry is the major tool of heat detection on most farms in Israel today. On many farms automated electronic pedometry is the sole mean of heat detection. Production and reproduction parameters are monitored by Hachaklait Veterinary Services Ltd. Results are compared with the farm history and with national means and goals. The average herd rate of undetected heat in more than 120 herds recorded between 2004 and 2008 has increased from 30.3 to 38.9% in primiparous cows and from 33.9 to 43.9% in multiparous cows respectively. The average duration of the waiting period has dropped from 106.2 to 93.4 days and from 99.9 to 87.3 days in primiparous and multiparous cows respectively. The average annual rate of cows shown on heat by pedometry and not inseminated by the A.I. technicians in recent years was 13% and remained steady. The mean herd rate of normal length heat cycles (18-24 days) in multiparous cows in recent years has been fairly steady; 57.4 to 58.4% of all cycles detected in 2004 and 2008 respectively. Herd rate of double cycles is also used to estimate the sensitivity of pedometry systems. Average rate of double cycles (37-60 days) per herd per annum in multiparous cows has dropped steadily from 22.6 to 20.1% between 2004 and 2008 respectively. Mean herd rate of short cycles in multiparous cows in 2008 was 7.4% Pregnancy checks are performed by the herds' veterinarians by transrectal palpation from 40 days post A.I. onward. In 2008 the average herd rate of negative pregnancy checks in cows was 27.5% (9.5-53.4%). The wide range indicates a large variability of pedometry system in tracking non-conceived cycling cows. Beside activity and heat detection pedometry systems record other individual cow parameters. A controlled field trial comparing between pedometry, observation and Ovsynch did not yield significant differences in reproductive measures.
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  • Han Sang YOO
    2010 Volume 56 Issue S Pages S53-S60
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    The incidences of reproductive disorders in bovine are increasing over years. This scenario is further aggravating due to more emphasis on selection and rearing of animal for specific commercial purposes which compromises livestock reproduction. Reproductive disorders like infertility and abortions in cattle are major problems in the bovine industry. The reproductive disorders might be caused by several different agents such as physical agents, chemical agents, biological agents, etc. Also, the causative agent and pathogenesis of reproductive disorders are influenced by various factors including environmental factor. The exact causes may not be evident and are often complicated with multiple causative agents. Thus, there is a need for multi-faceted approach to understand correlation of various factors with reproductive performance. Of the agents, infectious biological agents are significant cause of reproductive disorder and are of high priority in the bovine industry. These factors are not only related to the prosperity of bovine industry but are also important from public health point of view because of their zoonotic potentials. Several infectious agents like bacterial, viral, protozoon, chlamydial and fungal agents are known to have direct impact on reproductive health of cattle. These diseases can be arranged and discussed in different groups based on the causative agents.
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  • Osamu DOCHI, Sanae KABEYA, Hisaichi KOYAMA
    2010 Volume 56 Issue S Pages S61-S65
    Published: 2010
    Released on J-STAGE: August 10, 2010
    JOURNAL FREE ACCESS
    Although the number of dairy farms is decreasing, that of large farms is increasing in Japan. Milk production in Japanese dairy cows has increased from 62 kg/ year to 88 kg/ year over the last 2 decades. However, Japanese dairy cows are experiencing a sustained decline in reproductive performance, calving intervals, and days open; further, the number of inseminations required for conception have increased, and the conception rate has decreased. In order to improve fertility in high milk-producing dairy cows, it is necessary to evaluate their reproductive characteristics. In this study, the postpartum body condition score (BCS) was remarkably low, and the functional recovery of reproduction was consequently delayed. Moreover, the results indicate that the estrus duration varies among individual cows. However, it is possible to improve the conception rate by inseminating cows 8-12 h after the onset of estrus. Reproductive management systems suitable for the current dairy farming system with large herd sizes are required.
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