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<blockquote data-quote="Bez!" data-source="post: 156991" data-attributes="member: 2830"><p>This is a long one - but you might find it interesting. You may have agenetic problem. You may have a feed problem. You may have a condition problem - in fact there are numerous conditions that can create your personal circumstance.</p><p></p><p>This is a stolen article with contact numbers at the bottom - OMAF puts this out - some of the graphs do not paste well, but you can get some additional ideas from the reading if you are so inclined.</p><p></p><p>Here is the link for a better view of the tables and graphs.</p><p></p><p><a href="http://www.omafra.gov.on.ca/english/livestock/beef/facts/85-054.htm" target="_blank">http://www.omafra.gov.on.ca/english/liv ... 85-054.htm</a></p><p></p><p>Bez!</p><p></p><p>---------------------------------------------------</p><p>Breeding Season Management </p><p> </p><p></p><p>Author: J. Field - Beef Specialist/OMAF; N. Anderson - Cattle Diseases Consultant/OMAF </p><p>Creation Date: 01 September 1997 </p><p>Last Reviewed: 15 October 2003 </p><p></p><p>Table of Contents</p><p>Introduction </p><p>Reproductive Rate </p><p>Why Cows Do Not Become Pregnant </p><p>Time of Calving </p><p>Body Condition </p><p>Suckling </p><p>Weight Changes </p><p>Body Condition Scoring </p><p>The Bull </p><p>Bull to Cow Ratio </p><p>Example Breeding Program (Tom O'Connor) </p><p>Length of Breeding Season </p><p>Advantages of a Shortened Breeding Season </p><p>Breeding Replacement Heifers </p><p>Artificial Insemination (AI) </p><p>Heat Detection </p><p>Heat Detection Aids </p><p>Insemination Methods </p><p>Estrus Synchronization </p><p>Pregnancy Examination </p><p>Monitoring Reproductive Efficiency </p><p>Summary for Improved Reproductive Efficiency </p><p>References</p><p></p><p> Introduction</p><p>In analyzing the cow-calf industry, the four factors that are more commonly used by producers as influencing profit are:</p><p></p><p>weaning weight of the calves </p><p>percent of cows weaning calves </p><p>annual cost of maintaining the cow </p><p>the price received for the calves </p><p>In evaluating research on cow efficiency, it is apparent that one of the more important factors influencing the overall productivity and efficiency of the beef cow herd is reproductive efficiency.</p><p></p><p>Reproductive Rate </p><p></p><p>Table 1 - Miles City Study (Montana 14 yr) No. of cows Non-Pregnant at end of breeding season Calves lost during Gestation Lost Near Birth Lost Birth to 2 weeks Calf Crop Weaned </p><p>12,827 17.4% 2.3% 6.4% 2.9% 71.0% </p><p></p><p></p><p></p><p>If the percent calf crop is to be improved, the number of cows becoming pregnant must be increased and the losses near or shortly, after birth decreased.</p><p></p><p>| Top of Page |</p><p></p><p>Why Cows Do Not Become Pregnant</p><p>Much research has been done indicating that many cows fail to show heat early in the breeding season and also that conception rate at first service is low. If, however, proper management procedures are utilized the number of cows showing estrus the first 21 days of breeding as well as the conception rate at first service can be high.</p><p></p><p>Factors affecting the number of cows showing heat early in the breeding season and the number conceiving on first service are:</p><p></p><p></p><p>Showing Heat First 21 Days of Breeding </p><p>Conception Rate at First Service </p><p>(1) Time of Calving (1) Time of Calving </p><p>(2) Body condition of cows at calving time (2) Weight changes of cow near breeding time </p><p>(3) Age of the cow (3) Bull fertility </p><p>(4) Suckling (4) Bull to cow ratio </p><p></p><p></p><p></p><p> </p><p></p><p>Time of Calving Cows calving late in the calving season generally have a lower pregnancy rate because they do not have time to show estrus early in the breeding season.</p><p></p><p>Cows require adequate nutrition and rest post calving in order to cycle normally. Conception rate is higher in cows bred 60 days or more after calving.</p><p></p><p>Body Condition is important in determining when a cow shows estrus following calving. Ninety-one percent of the cows in good body condition at calving had shown estrus by 60 days post-calving, as compared with 61 % of the cows in moderate condition and 46% of the cows in thin body condition.</p><p></p><p>Table 2: Body Condition at Calving and Heat after Calving </p><p>Days after Calving (%) </p><p></p><p>Body Condition at Calving </p><p>No. of Cows </p><p>40 </p><p>50 </p><p>60 </p><p>70 </p><p>80 </p><p>90 </p><p>100 </p><p>120 </p><p>Thin </p><p>272 </p><p>19 </p><p>34 </p><p>46 </p><p>55 </p><p>62 </p><p>66 </p><p>70 </p><p>77 </p><p>Moderate </p><p>364 </p><p>21 </p><p>45 </p><p>61 </p><p>79 </p><p>88 </p><p>92 </p><p>100 </p><p>100 </p><p>Good </p><p>50 </p><p>31 </p><p>42 </p><p>91 </p><p>96 </p><p>98 </p><p>100 </p><p>100 </p><p>100 </p><p></p><p></p><p>Ref: Wiltbank </p><p></p><p>| Top of Page |</p><p></p><p>Suckling Cows that are suckled have longer intervals from calving to first estrus. Flushing and 48-hour calf removal can be helpful in improving reproductive performance. Neither practice alone is as beneficial as a combination of the two.</p><p></p><p>Removing calves for 48 hours can be a problem in some situations. The best way to accomplish this is to combine calf removal with working the calves. Calves must not nurse for 48 hours to get maximum results.</p><p></p><p>Weight Changes near breeding time affect pregnancy rate. Sixty-seven percent of the cows that held their weight from calving to breeding conceived on first service as compared with 43% in cows losing weight during this period. The pregnancy rate after 21 and 90 days of breeding was also higher in cows holding their weight as compared with cows losing weight.</p><p></p><p>Body Condition Scoring As has been discussed, body condition of the cow at calving (moderate or good) and post calving to breeding will have a direct bearing on improved breeding efficiency.</p><p></p><p>Most scoring systems have been based on palpation of the back and hindquarters of the cow. Particular attention is given to the chine, loin. rump, tail head. hook bone and pin bone regions. Cows in one system are scored on a scale of 1 to 5. A score of 1 indicates severe under conditioning while a score of 5 is assigned to over conditioned obese cows.</p><p></p><p>Scoring System</p><p></p><p>Score 1 Individual spinous processes have limited flesh cover; the ends are sharp to touch; they give a definite overhanging shelf effect to the loin region.</p><p></p><p>Score 2 Transverse processes can be felt, but not prominent; rounded with some fat cover.</p><p></p><p>Score 3 Transverse processes can be felt with firm pressure; processes appear smooth; the overhanging shelf effect is not noticeable.</p><p></p><p>Score 4 Individual processes only felt with very firm pressure; rounded with no overhanging shelf effect; loin and rump appear flat; tail head and pins are rounded.</p><p></p><p>Score 5 The structure of the transverse processes, hook and pin bone region is not apparent; fat deposition is obvious and prominent.</p><p></p><p>Ref: E.E. Wildman</p><p></p><p></p><p></p><p></p><p>The relationship noted above has led to the recommendation of a </p><p></p><p></p><p>Mating Target Score 2½ </p><p></p><p>It may not be necessary or practical to palpate all cows under most circumstances but an understanding of the scoring system and what is involved would allow eye-balling or visual appraisal of cows to evaluate condition.</p><p></p><p>Cows should be in moderate to good body condition at calving time to attain optimum reproductive performance.</p><p></p><p>Possible Scoring Use</p><p></p><p>Observe cows one or two months before calves are scheduled to be weaned. If cows are thin, supplement feed or wean calves. </p><p>Sort cows by body condition at weaning time - feed accordingly. </p><p>Prior to calving. </p><p>Middle of calving season (prior to breeding) </p><p>Suitable adjustments must be made to the feeding program to meet the target score if cows are indeed too thin.</p><p></p><p>| Top of Page |</p><p></p><p>The Bull</p><p></p><p>Condition and nutrition of the bull prior to breeding are equally important to breeding efficiency.</p><p></p><p>Unfortunately very few bulls undergo any thorough breeding soundness examinations prior to the breeding season.</p><p></p><p>A breeding soundness examination would involve:</p><p></p><p>Conformation </p><p>Physical Examination </p><p>scrotum and testicles </p><p>scrotal circumference </p><p>penis and prepuce </p><p>Semen Evaluation </p><p>volume </p><p>concentration </p><p>mortality and morphology </p><p>Scrotal Circumference</p><p></p><p>Research has documented that testicular and scrotal development is directly related to sperm production and fertility in bulls. Scrotal circumference measurement properly done provides an aid in selecting sires with normal testicular development and is of considerable importance, particularly in yearling bulls.</p><p></p><p>Factors Affecting Bull Reproductive Potential</p><p></p><p>Testicular and scrotal development. </p><p>Ability to physically breed females. </p><p>Semen quality and volume. </p><p>Libido or serving capacity. </p><p>All four are of equal importance and testing would be a recommended procedure where practical before a bull is used.</p><p></p><p> </p><p></p><p>Table 3. Scrotal Circumference in Centimetres* Age (months) </p><p>Classification </p><p>12-14 </p><p>14-20 </p><p>21-30 </p><p>30+ </p><p>Very Good </p><p>>35 </p><p>>37 </p><p>>39 </p><p>>40 </p><p>Poor </p><p><30 </p><p><31 </p><p><32 </p><p><33 </p><p></p><p></p><p></p><p> </p><p></p><p>*The average scrotal circumference will vary according to breed.</p><p></p><p>| Top of Page |</p><p></p><p>Bull to Cow Ratio</p><p></p><p>Table 4. Number of Cows per Bull </p><p>Bull Age </p><p>Mating System </p><p></p><p>Pasture Mating </p><p>Hand Mating </p><p></p><p>Yearling </p><p>10-20 </p><p>20-30 </p><p></p><p>2 year old </p><p>20-30 </p><p>30-40 </p><p></p><p>3 year olds & older </p><p>30-40 </p><p>40-60 </p><p></p><p></p><p></p><p>These figures vary considerably with the condition of the pasture, the sex drive of the bull, the fertility level of the cow herd and the length of the breeding season.</p><p></p><p>| Top of Page |</p><p></p><p>Example Breeding Program (Tom O'Connor)</p><p>The O'Connor program involves five factors:</p><p></p><p>Sixty-day breeding. </p><p>Cows in moderate or good condition at calving time. </p><p>Cows gain in weight for three weeks before the start of breeding season and during breeding season. </p><p>Calves removed from cows for 48 hours at start of breeding season.* </p><p>Cows bred to fertile bulls. </p><p>* This factor may not be practical to the majority of commercial producers.</p><p></p><p>Eighty percent of the cows were pregnant after 30 days of breeding in the O'Connor herd that utilized these five factors. After 42 days of breeding, 87% were pregnant.</p><p></p><p>| Top of Page |</p><p></p><p>Length of Breeding Season</p><p>The length of the breeding season is an important factor in determining pregnancy rate. It has been shown that late-calving cows have smaller calf crops than do early calving cows. The only reliable method for making sure cows calve early in the calving season is to have a short breeding season.</p><p></p><p>A 60-90 day breeding season should be a goal of most cow-calf producers with 45 to 60 days being more desirable. This could be achieved by gradually reducing the breeding season each year by 2-3 weeks which would result in fewer open cows being culled within a given year. Adequate nutrition and management are essential to success.</p><p></p><p>Table 5. Effect of Shortening the Calving Season </p><p>Year </p><p>No. of Cows </p><p>No. of Heifers </p><p>Length of Breeding Season (Mo) </p><p>Calving in Desired Time (%)* </p><p>Calf Crop </p><p>Weaning Weight </p><p>Pounds of Calf Per Cow Exposed </p><p></p><p>Actual </p><p>At 205 Days </p><p></p><p>1st </p><p>74 </p><p>0 </p><p>11 </p><p>38 </p><p>69 </p><p>400 </p><p>400 </p><p>272 </p><p></p><p>2nd </p><p>63 </p><p>3 </p><p>7 </p><p>62 </p><p>85 </p><p>428 </p><p>432 </p><p>295 </p><p></p><p>3rd </p><p>52 </p><p>17 </p><p>3 </p><p>89 </p><p>86 </p><p>476 </p><p>452 </p><p>405 </p><p></p><p>4th </p><p>58 </p><p>23 </p><p>2 </p><p>100 </p><p>83 </p><p>509 </p><p>459 </p><p>499 </p><p>*Of cows calved Ref: Spitzer </p><p></p><p>| Top of Page |</p><p></p><p>Advantages of a Shortened Breeding Season</p><p>More concentrated management (time and labor). </p><p>More uniform group of calves by age, size and weight to sell at weaning. </p><p>More uniform group of calves by age, size and weight to feed as a management group if calves are kept and fed. </p><p>Early calving cows usually wean heavier calves. </p><p>Nutrient requirements of the cow herd will be much easier to meet during the critical stages of the production cycle with all cows calving within a shorter period. </p><p>Eliminate cattle with low fertility from the breeding herd. </p><p>With shorter breeding seasons success will be dependent on feeding and breeding management. Adequate nutrition and rest are essentials to fertile and cycling cows. Equally important is the health, condition and fertility of the bull if natural service is used. During the breeding season it is important that the herd be checked routinely to observe breeding progress.</p><p></p><p>| Top of Page |</p><p></p><p>Breeding Replacement Heifers</p><p>When considering a shortened breeding season, heifer management at breeding will be of importance. Yearling replacement heifers should be bred 3 weeks prior to the breeding of the mature cow herd. Heifers will require a longer period of time to begin cycling and show heat after calving than mature females. Heifers bred before the main cow herd, will calve earlier in the season and will be cycling normally by the time the main cow herd is being bred the following year. If we want a heifer to be a good lifetime producer she must calve early. She must show heat and conceive early in the breeding season. Heifers calving late usually become late calving cows.</p><p></p><p>The lifetime production of beef females can be increased by calving at two years of age. This can be achieved by producers willing to provide the required nutrition and management.</p><p></p><p>Table 6. Reproductive Performance in Hereford Heifers as Influenced by Weight at Start of Breeding </p><p>(Tom O'Connor) Under 550 lbs 551-600 lbs Over 600 lbs </p><p>No. Heifers 40 166 45 </p><p>Pregnant 60 days (%) 65 77 90 </p><p>Calves weaned (%) 40 71 86 </p><p>Losses pregnancy exam - weaning (%) 25 6 4 </p><p>Wet cows pregnant - 2nd year (%) 18 57 69 </p><p></p><p></p><p></p><p>| Top of Page |</p><p></p><p>Artificial Insemination (AI)</p><p>Those considering or using AI should ensure that the breeding season does not become lengthened in attempts to settle cows. Top breeding management is required for successful heat detection and high conception rates with AI.</p><p></p><p>A suggested practice would be to breed the top end of the herd AI the first 25-30 days of the breeding season and use a clean-up bull or bulls for the remainder of the breeding period.</p><p></p><p>A sound health program and good nutrition are requirements of any breeding program. They become even more important in an AI program.</p><p></p><p>Proper handling facilities are essential to an AI program. They can be very simple or elaborate. Anything that can be done to reduce handling stress will greatly increase conception rates.</p><p></p><p>Success with artificial insemination requires top management. Management must be willing to provide the additional labor which will always be above the requirements for natural mating.</p><p></p><p>Heat Detection</p><p></p><p>Individual cow identification visible from a distance and adequate records are essential components of a successful heat detection program.</p><p></p><p>Table 7. Heat Detection </p><p>Number of Observation Periods </p><p>% Cows seen in Heat </p><p>Once a day </p><p>60 </p><p>Twice a day </p><p>80 </p><p>Three times a day </p><p>90 </p><p>Four times a day </p><p>100 </p><p></p><p></p><p>A higher detection rate of cows in heat has been observed before noon than during the afternoon and evening. Shortly after sunrise a special effort should be made to detect heat.</p><p></p><p>| Top of Page |</p><p></p><p>Heat Detection Aids</p><p></p><p>Kamar Patch - pressure sensitive devices glued to the rump of cows for heat detection. </p><p>Sterilized Bulls - surgically altered bulls. </p><p>Teaser Bulls </p><p>Hopped up Heifers - heifers treated with hormones. </p><p>Chin Ball Marker - detector animal fitted with this marker. </p><p>Insemination Methods</p><p>Cleanliness during all insemination procedures is essential and is a critical point for success or failure.</p><p></p><p>Estrus Synchronization</p><p></p><p>Injection of a natural or synthetic prostaglandin will induce heat in sexually mature and cycling females. Cattle which are not reproductively cycling must not be included in an estrus synchronizing program.</p><p></p><p>Estrus synchronization with prostaglandins has the potential to improve and increase artificial insemination (AI) programs with cattle.</p><p></p><p>Controlled breeding programs will reduce time and labor involved with heat detection and shorten both the breeding season and calving season. Total Cost factors would have to be considered.</p><p></p><p>With good management this program can be successful.</p><p></p><p>| Top of Page |</p><p></p><p>Pregnancy Examination</p><p></p><p>Pregnancy examination as a routine practice at the end of the breeding season can be an important tool in improving the efficiency within the beef cow herd. Identifying open cows which can be effectively marketed will reduce wintering costs and increase efficiency of production.</p><p></p><p>Pregnancy examination should take place 6 to 8 weeks after the end of breeding season.</p><p></p><p>Advantages of early pregnancy diagnosis in beef cattle are:</p><p></p><p>I. Gives warning of breeding problems (infertility and problem breeders)</p><p></p><p>II. Improved fertility - effective culling and marketing of problem breeders.</p><p></p><p>III. Reduced overhead costs - effective use of time, labor, facilities, etc.</p><p></p><p>IV. Guarantee pregnancy in females for sale.</p><p></p><p>| Top of Page |</p><p></p><p>Monitoring Reproductive Efficiency</p><p>Records are essential to identify where losses occur in the reproductive cycle. This summary (Table 8) will permit calculation of reproductive performance indices that will enable you and your veterinarian to make breeding management decisions.</p><p></p><p>Records are essential to identify where losses occur in the reproductive cycle. The following summary will permit calculation of reproductive performance indices that will enable you and your veterinarian to make breeding management decisions.</p><p></p><p>Table 8. Monitoring Reproductive Efficiency </p><p> </p><p>Heifers </p><p>Cows </p><p>Breeding History </p><p></p><p></p><p> </p><p>1. Number exposed to natural service </p><p> </p><p>__________ </p><p>__________ </p><p>2. Date bulls turned out </p><p> </p><p>__________ </p><p>__________ </p><p>3. Date bulls removed </p><p> </p><p>__________ </p><p>__________ </p><p>4. Number of bulls used in 2 & 3 </p><p> </p><p>__________ </p><p>__________ </p><p>5. Number exposed to artificial service </p><p> </p><p>__________ </p><p>__________ </p><p>6. Date first AI service </p><p> </p><p>__________ </p><p>__________ </p><p>7. Date last AI service </p><p> </p><p>__________ </p><p>__________ </p><p>8. Total number of AI services </p><p> </p><p>__________ </p><p>__________ </p><p>9. Number pregnant by natural service </p><p> </p><p>__________ </p><p>__________ </p><p>10. Number pregnant by artificial service </p><p> </p><p>__________ </p><p>__________ </p><p>11. Date of pregnancy check </p><p> </p><p>__________ </p><p>__________ </p><p>Breeding to Calving Period (died = culled) </p><p></p><p></p><p> </p><p>12. Number of open cows culled </p><p> </p><p>__________ </p><p>__________ </p><p>13. Number of open cows sold </p><p> </p><p>__________ </p><p>__________ </p><p>14. Number of pregnant cows culled </p><p> </p><p>__________ </p><p>__________ </p><p>15. Number of pregnant cows sold </p><p> </p><p>__________ </p><p>__________ </p><p>16. Number of abortions </p><p> </p><p>__________ </p><p>__________ </p><p>17. Number due to calve </p><p> </p><p>__________ </p><p>__________ </p><p>Calving History </p><p></p><p></p><p> </p><p>18. Number of liveborn calves </p><p> </p><p>__________ </p><p>__________ </p><p>19. Number of stillbirths </p><p> </p><p>__________ </p><p>__________ </p><p>20. Date first calving </p><p> </p><p>__________ </p><p>__________ </p><p>21. Date of last calving </p><p> </p><p>__________ </p><p>__________ </p><p>22. Number barren </p><p> </p><p>__________ </p><p>__________ </p><p></p><p></p><p></p><p>| Top of Page |</p><p></p><p>Summary for Improved Reproductive Efficiency</p><p></p><p>Body condition score </p><p>Nutrition - bulls and cows </p><p>Breeding soundness examinations </p><p>Bull to cow ratio </p><p>Breed heifers - target age 14-15 months - 3 weeks before cows. </p><p>Breeding season 45-60 days </p><p>Calving season 45-60 days </p><p>Pregnancy Examination </p><p>Cull open or barren cows </p><p>Monitor performance. </p><p>A highly managed cow herd will be much more efficient and productive. Discuss your reproductive program with your local veterinarian, and/or AI company.</p><p></p><p> </p><p></p><p>References</p><p>Beef Cow Efficiency Forum '84 L. Corah </p><p>Cattlemen's Library </p><p>Veterinary Clinics of North America. J.N. Wiltbank </p><p>| Top of Page |</p><p></p><p>For more information:</p><p>Toll Free: 1-877-424-1300 </p><p>Local: (519) 826-4047 </p><p>Email: <a href="mailto:ag.info@omaf.gov.on.ca">ag.info@omaf.gov.on.ca</a></p></blockquote><p></p>
[QUOTE="Bez!, post: 156991, member: 2830"] This is a long one - but you might find it interesting. You may have agenetic problem. You may have a feed problem. You may have a condition problem - in fact there are numerous conditions that can create your personal circumstance. This is a stolen article with contact numbers at the bottom - OMAF puts this out - some of the graphs do not paste well, but you can get some additional ideas from the reading if you are so inclined. Here is the link for a better view of the tables and graphs. [url=http://www.omafra.gov.on.ca/english/livestock/beef/facts/85-054.htm]http://www.omafra.gov.on.ca/english/liv ... 85-054.htm[/url] Bez! --------------------------------------------------- Breeding Season Management Author: J. Field - Beef Specialist/OMAF; N. Anderson - Cattle Diseases Consultant/OMAF Creation Date: 01 September 1997 Last Reviewed: 15 October 2003 Table of Contents Introduction Reproductive Rate Why Cows Do Not Become Pregnant Time of Calving Body Condition Suckling Weight Changes Body Condition Scoring The Bull Bull to Cow Ratio Example Breeding Program (Tom O'Connor) Length of Breeding Season Advantages of a Shortened Breeding Season Breeding Replacement Heifers Artificial Insemination (AI) Heat Detection Heat Detection Aids Insemination Methods Estrus Synchronization Pregnancy Examination Monitoring Reproductive Efficiency Summary for Improved Reproductive Efficiency References Introduction In analyzing the cow-calf industry, the four factors that are more commonly used by producers as influencing profit are: weaning weight of the calves percent of cows weaning calves annual cost of maintaining the cow the price received for the calves In evaluating research on cow efficiency, it is apparent that one of the more important factors influencing the overall productivity and efficiency of the beef cow herd is reproductive efficiency. Reproductive Rate Table 1 - Miles City Study (Montana 14 yr) No. of cows Non-Pregnant at end of breeding season Calves lost during Gestation Lost Near Birth Lost Birth to 2 weeks Calf Crop Weaned 12,827 17.4% 2.3% 6.4% 2.9% 71.0% If the percent calf crop is to be improved, the number of cows becoming pregnant must be increased and the losses near or shortly, after birth decreased. | Top of Page | Why Cows Do Not Become Pregnant Much research has been done indicating that many cows fail to show heat early in the breeding season and also that conception rate at first service is low. If, however, proper management procedures are utilized the number of cows showing estrus the first 21 days of breeding as well as the conception rate at first service can be high. Factors affecting the number of cows showing heat early in the breeding season and the number conceiving on first service are: Showing Heat First 21 Days of Breeding Conception Rate at First Service (1) Time of Calving (1) Time of Calving (2) Body condition of cows at calving time (2) Weight changes of cow near breeding time (3) Age of the cow (3) Bull fertility (4) Suckling (4) Bull to cow ratio Time of Calving Cows calving late in the calving season generally have a lower pregnancy rate because they do not have time to show estrus early in the breeding season. Cows require adequate nutrition and rest post calving in order to cycle normally. Conception rate is higher in cows bred 60 days or more after calving. Body Condition is important in determining when a cow shows estrus following calving. Ninety-one percent of the cows in good body condition at calving had shown estrus by 60 days post-calving, as compared with 61 % of the cows in moderate condition and 46% of the cows in thin body condition. Table 2: Body Condition at Calving and Heat after Calving Days after Calving (%) Body Condition at Calving No. of Cows 40 50 60 70 80 90 100 120 Thin 272 19 34 46 55 62 66 70 77 Moderate 364 21 45 61 79 88 92 100 100 Good 50 31 42 91 96 98 100 100 100 Ref: Wiltbank | Top of Page | Suckling Cows that are suckled have longer intervals from calving to first estrus. Flushing and 48-hour calf removal can be helpful in improving reproductive performance. Neither practice alone is as beneficial as a combination of the two. Removing calves for 48 hours can be a problem in some situations. The best way to accomplish this is to combine calf removal with working the calves. Calves must not nurse for 48 hours to get maximum results. Weight Changes near breeding time affect pregnancy rate. Sixty-seven percent of the cows that held their weight from calving to breeding conceived on first service as compared with 43% in cows losing weight during this period. The pregnancy rate after 21 and 90 days of breeding was also higher in cows holding their weight as compared with cows losing weight. Body Condition Scoring As has been discussed, body condition of the cow at calving (moderate or good) and post calving to breeding will have a direct bearing on improved breeding efficiency. Most scoring systems have been based on palpation of the back and hindquarters of the cow. Particular attention is given to the chine, loin. rump, tail head. hook bone and pin bone regions. Cows in one system are scored on a scale of 1 to 5. A score of 1 indicates severe under conditioning while a score of 5 is assigned to over conditioned obese cows. Scoring System Score 1 Individual spinous processes have limited flesh cover; the ends are sharp to touch; they give a definite overhanging shelf effect to the loin region. Score 2 Transverse processes can be felt, but not prominent; rounded with some fat cover. Score 3 Transverse processes can be felt with firm pressure; processes appear smooth; the overhanging shelf effect is not noticeable. Score 4 Individual processes only felt with very firm pressure; rounded with no overhanging shelf effect; loin and rump appear flat; tail head and pins are rounded. Score 5 The structure of the transverse processes, hook and pin bone region is not apparent; fat deposition is obvious and prominent. Ref: E.E. Wildman The relationship noted above has led to the recommendation of a Mating Target Score 2½ It may not be necessary or practical to palpate all cows under most circumstances but an understanding of the scoring system and what is involved would allow eye-balling or visual appraisal of cows to evaluate condition. Cows should be in moderate to good body condition at calving time to attain optimum reproductive performance. Possible Scoring Use Observe cows one or two months before calves are scheduled to be weaned. If cows are thin, supplement feed or wean calves. Sort cows by body condition at weaning time - feed accordingly. Prior to calving. Middle of calving season (prior to breeding) Suitable adjustments must be made to the feeding program to meet the target score if cows are indeed too thin. | Top of Page | The Bull Condition and nutrition of the bull prior to breeding are equally important to breeding efficiency. Unfortunately very few bulls undergo any thorough breeding soundness examinations prior to the breeding season. A breeding soundness examination would involve: Conformation Physical Examination scrotum and testicles scrotal circumference penis and prepuce Semen Evaluation volume concentration mortality and morphology Scrotal Circumference Research has documented that testicular and scrotal development is directly related to sperm production and fertility in bulls. Scrotal circumference measurement properly done provides an aid in selecting sires with normal testicular development and is of considerable importance, particularly in yearling bulls. Factors Affecting Bull Reproductive Potential Testicular and scrotal development. Ability to physically breed females. Semen quality and volume. Libido or serving capacity. All four are of equal importance and testing would be a recommended procedure where practical before a bull is used. Table 3. Scrotal Circumference in Centimetres* Age (months) Classification 12-14 14-20 21-30 30+ Very Good >35 >37 >39 >40 Poor <30 <31 <32 <33 *The average scrotal circumference will vary according to breed. | Top of Page | Bull to Cow Ratio Table 4. Number of Cows per Bull Bull Age Mating System Pasture Mating Hand Mating Yearling 10-20 20-30 2 year old 20-30 30-40 3 year olds & older 30-40 40-60 These figures vary considerably with the condition of the pasture, the sex drive of the bull, the fertility level of the cow herd and the length of the breeding season. | Top of Page | Example Breeding Program (Tom O'Connor) The O'Connor program involves five factors: Sixty-day breeding. Cows in moderate or good condition at calving time. Cows gain in weight for three weeks before the start of breeding season and during breeding season. Calves removed from cows for 48 hours at start of breeding season.* Cows bred to fertile bulls. * This factor may not be practical to the majority of commercial producers. Eighty percent of the cows were pregnant after 30 days of breeding in the O'Connor herd that utilized these five factors. After 42 days of breeding, 87% were pregnant. | Top of Page | Length of Breeding Season The length of the breeding season is an important factor in determining pregnancy rate. It has been shown that late-calving cows have smaller calf crops than do early calving cows. The only reliable method for making sure cows calve early in the calving season is to have a short breeding season. A 60-90 day breeding season should be a goal of most cow-calf producers with 45 to 60 days being more desirable. This could be achieved by gradually reducing the breeding season each year by 2-3 weeks which would result in fewer open cows being culled within a given year. Adequate nutrition and management are essential to success. Table 5. Effect of Shortening the Calving Season Year No. of Cows No. of Heifers Length of Breeding Season (Mo) Calving in Desired Time (%)* Calf Crop Weaning Weight Pounds of Calf Per Cow Exposed Actual At 205 Days 1st 74 0 11 38 69 400 400 272 2nd 63 3 7 62 85 428 432 295 3rd 52 17 3 89 86 476 452 405 4th 58 23 2 100 83 509 459 499 *Of cows calved Ref: Spitzer | Top of Page | Advantages of a Shortened Breeding Season More concentrated management (time and labor). More uniform group of calves by age, size and weight to sell at weaning. More uniform group of calves by age, size and weight to feed as a management group if calves are kept and fed. Early calving cows usually wean heavier calves. Nutrient requirements of the cow herd will be much easier to meet during the critical stages of the production cycle with all cows calving within a shorter period. Eliminate cattle with low fertility from the breeding herd. With shorter breeding seasons success will be dependent on feeding and breeding management. Adequate nutrition and rest are essentials to fertile and cycling cows. Equally important is the health, condition and fertility of the bull if natural service is used. During the breeding season it is important that the herd be checked routinely to observe breeding progress. | Top of Page | Breeding Replacement Heifers When considering a shortened breeding season, heifer management at breeding will be of importance. Yearling replacement heifers should be bred 3 weeks prior to the breeding of the mature cow herd. Heifers will require a longer period of time to begin cycling and show heat after calving than mature females. Heifers bred before the main cow herd, will calve earlier in the season and will be cycling normally by the time the main cow herd is being bred the following year. If we want a heifer to be a good lifetime producer she must calve early. She must show heat and conceive early in the breeding season. Heifers calving late usually become late calving cows. The lifetime production of beef females can be increased by calving at two years of age. This can be achieved by producers willing to provide the required nutrition and management. Table 6. Reproductive Performance in Hereford Heifers as Influenced by Weight at Start of Breeding (Tom O'Connor) Under 550 lbs 551-600 lbs Over 600 lbs No. Heifers 40 166 45 Pregnant 60 days (%) 65 77 90 Calves weaned (%) 40 71 86 Losses pregnancy exam - weaning (%) 25 6 4 Wet cows pregnant - 2nd year (%) 18 57 69 | Top of Page | Artificial Insemination (AI) Those considering or using AI should ensure that the breeding season does not become lengthened in attempts to settle cows. Top breeding management is required for successful heat detection and high conception rates with AI. A suggested practice would be to breed the top end of the herd AI the first 25-30 days of the breeding season and use a clean-up bull or bulls for the remainder of the breeding period. A sound health program and good nutrition are requirements of any breeding program. They become even more important in an AI program. Proper handling facilities are essential to an AI program. They can be very simple or elaborate. Anything that can be done to reduce handling stress will greatly increase conception rates. Success with artificial insemination requires top management. Management must be willing to provide the additional labor which will always be above the requirements for natural mating. Heat Detection Individual cow identification visible from a distance and adequate records are essential components of a successful heat detection program. Table 7. Heat Detection Number of Observation Periods % Cows seen in Heat Once a day 60 Twice a day 80 Three times a day 90 Four times a day 100 A higher detection rate of cows in heat has been observed before noon than during the afternoon and evening. Shortly after sunrise a special effort should be made to detect heat. | Top of Page | Heat Detection Aids Kamar Patch - pressure sensitive devices glued to the rump of cows for heat detection. Sterilized Bulls - surgically altered bulls. Teaser Bulls Hopped up Heifers - heifers treated with hormones. Chin Ball Marker - detector animal fitted with this marker. Insemination Methods Cleanliness during all insemination procedures is essential and is a critical point for success or failure. Estrus Synchronization Injection of a natural or synthetic prostaglandin will induce heat in sexually mature and cycling females. Cattle which are not reproductively cycling must not be included in an estrus synchronizing program. Estrus synchronization with prostaglandins has the potential to improve and increase artificial insemination (AI) programs with cattle. Controlled breeding programs will reduce time and labor involved with heat detection and shorten both the breeding season and calving season. Total Cost factors would have to be considered. With good management this program can be successful. | Top of Page | Pregnancy Examination Pregnancy examination as a routine practice at the end of the breeding season can be an important tool in improving the efficiency within the beef cow herd. Identifying open cows which can be effectively marketed will reduce wintering costs and increase efficiency of production. Pregnancy examination should take place 6 to 8 weeks after the end of breeding season. Advantages of early pregnancy diagnosis in beef cattle are: I. Gives warning of breeding problems (infertility and problem breeders) II. Improved fertility - effective culling and marketing of problem breeders. III. Reduced overhead costs - effective use of time, labor, facilities, etc. IV. Guarantee pregnancy in females for sale. | Top of Page | Monitoring Reproductive Efficiency Records are essential to identify where losses occur in the reproductive cycle. This summary (Table 8) will permit calculation of reproductive performance indices that will enable you and your veterinarian to make breeding management decisions. Records are essential to identify where losses occur in the reproductive cycle. The following summary will permit calculation of reproductive performance indices that will enable you and your veterinarian to make breeding management decisions. Table 8. Monitoring Reproductive Efficiency Heifers Cows Breeding History 1. Number exposed to natural service __________ __________ 2. Date bulls turned out __________ __________ 3. Date bulls removed __________ __________ 4. Number of bulls used in 2 & 3 __________ __________ 5. Number exposed to artificial service __________ __________ 6. Date first AI service __________ __________ 7. Date last AI service __________ __________ 8. Total number of AI services __________ __________ 9. Number pregnant by natural service __________ __________ 10. Number pregnant by artificial service __________ __________ 11. Date of pregnancy check __________ __________ Breeding to Calving Period (died = culled) 12. Number of open cows culled __________ __________ 13. Number of open cows sold __________ __________ 14. Number of pregnant cows culled __________ __________ 15. Number of pregnant cows sold __________ __________ 16. Number of abortions __________ __________ 17. Number due to calve __________ __________ Calving History 18. Number of liveborn calves __________ __________ 19. Number of stillbirths __________ __________ 20. Date first calving __________ __________ 21. Date of last calving __________ __________ 22. Number barren __________ __________ | Top of Page | Summary for Improved Reproductive Efficiency Body condition score Nutrition - bulls and cows Breeding soundness examinations Bull to cow ratio Breed heifers - target age 14-15 months - 3 weeks before cows. Breeding season 45-60 days Calving season 45-60 days Pregnancy Examination Cull open or barren cows Monitor performance. A highly managed cow herd will be much more efficient and productive. Discuss your reproductive program with your local veterinarian, and/or AI company. References Beef Cow Efficiency Forum '84 L. Corah Cattlemen's Library Veterinary Clinics of North America. J.N. Wiltbank | Top of Page | For more information: Toll Free: 1-877-424-1300 Local: (519) 826-4047 Email: [email=ag.info@omaf.gov.on.ca]ag.info@omaf.gov.on.ca[/email] [/QUOTE]
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