ows that are slow to breed or fail to breed areitability Many factors - PDF document

ows that are slow to breed or fail to breed areitability. Many factors affect a cowÕs ability tobreed after calving. Assuming that reproductive dis-eases are not prevalent in the herd, the most com-mon cause of slow breeding and failure to breed isResearch trials have found that cows that are prop-erly nourished have the highest pregnancy rates andbreed quicker after calving. Cow age is another fac-tor that affects pregnancy rates in calving cows.First-calf heifers are slower than mature cowsto resume estrous cycles, making it more difficult fora young female to breed. A final factor Ñ nursingstress Ñ delays the resumption of estrous activitySuckling activity by a calf alters the release and thelevel of hormones required by the cow to resume herestrous cycles after calving. Removing a calf fromthe dam, either short-term or permanently, reducesactivity. In poorly nourished females, the result isimproved reproductive performance.Altering Nursing ActivityAlthough many producers put their best efforts intoproviding adequate nutrition for their herd, extremeweather conditions such as drought or extended cold can reduce the effectiveness of a proper feeding pro-gram. Under such conditions, calving females will benutritionally stressed, and their ability to resumeestrous activity becomes limited. In worst cases ofextended weather extremes, estrous activity may beso limited that few, if any, females will breed. Otherfactors can also result in nutritional stress, including:Excessive grazing pressure (over-grazing)Inadequate quality of feed. A Way to Stimulate Reproduction in CowsL.R. Sprott, Professor, Extension Beef Cattle Specialist and Research ScientistTexas Cooperative Extension, The Texas A&M University System L-54439/03 at an early age - 60 days or older) or selling calves atan early age (80 to 100 days old).Short-Term Calf RemovalThis method is commonly called 48-hour calfremoval and is the least aggressive method of alter-ing nursing activity. It is recommended only foreffective in females under severe nutritional stress.As the name implies, calves are not allowed to nursetheir dams for 2 days. The calves should be placed invents the calves from getting out and nursing. While the calves are away from their dams, providefresh water, high quality hay or grazing plus 2-3pounds of a creep or grower ration. To lessen the riskof younger calves becoming orphaned or ill, it is bestnot to use this method until they are at least 45 daysof age. Do not use this method if inclement weather(cold and rainy) is expected during the period thatcalves are to be removed from their dams. Instead,wait for milder weather. removal will resume their estrous cycles withinapproximately 20 days, depending on the degree ofcalf. Pregnancy rates in the first 21 days of breedingafter 48-hour calf removal will us

ually be twice thepregnancy rates of cows whose calves have not beenremoved. Some people who use short-term calf removal sepa-rate calves from their dams for up to 72 hours.Research has shown, however, that the benefitsallow calves time to properly Òmother-upÓ inside apen or trap at the end of the 48-hour period, espe-cially if they are to be subsequently herded or trans-ported.Once-Daily SucklingAs its name implies, calves are allowed to nurse onlyonce a day. Certainly, the once-daily suckling methodrequires the producer to sort the cows from theircalves daily, but if done properly, this method neednot last more than 40 to 50 days. When the cows are turned in each day (either morn-ing or evening), the calves will nurse their dams for30 to 45 minutes, the time required for most calvesto become full. The cows are then returned to theirpasture. In most cases, all females will resumeestrous activity within 40 days of the start of once-daily suckling as long as they are being given mod- tional stress. mal handling, it allows the producer to retain thecalves to a marketable age without sacrificing themat a young age, as with permanent calf removal.While away from their dams, calves require feedsupplements of high quality hay or grazing, plus 2-3pounds of a creep or grower ration per calf daily. Besure to provide adequate mineral supplements. As calves get older, or grazing becomes limited, up to4 pounds of creep or grower ration may be needed.It is best not to use this method on calves less than45 days of age due to increased risk of illness inyounger calves. Medicated supplements may helpreduce potential illness in the calves, but consult aveterinarian before using medicated feeds. If expo-sure to weather is a problem, provide shade andshelter for the calves. Try not to house the calves ina crowded and/or dusty pen; provide instead a smalltrap or pasture. Be sure to check for illness and pro-vide any necessary medications.Early WeaningThis is also an aggressive and effective method ofstimulating reproductive performance. Calves arepermanently placed in a feed trap or pasture awayfrom the dams and not allowed to nurse. Calvesshould be reared on high quality grazing or hay andgiven appropriate supplemental feeds as would bedone with once-daily suckling. It is best to wait untilcalves are at least 60 to 80 days old before imple-menting early weaning. Younger calves may experience a high degree of ill-ness under these conditions. Be sure to monitorcalves closely for illness during the first 30 - 45 daysafter weaning. Treat sick calves and provide shadeand shelter to avoid unacceptable rates of illness. Ifacceptable weather conditions exist during the first 2to 3 weeks of the early weaning period, illness ratesgenerally do not exceed 20 percent. They can, how-ever, be higher if there is a hig

h proportion of calvesyounger than 60 days old. It can be expected that allfemales will resume estrous activity within 30 daysof initiating early weaning.Selling Calves at 80 to 100 DaysIn the early days of ranching, many producers dis-covered that a cow would show a high incidence ofbreeding activity within a 2 to 3 week period follow-ing the accidental loss of her calf. They also noticedthat thin cows would not resume estrous activityuntil their calves were sent to market. 2 These ÒformsÓ of calf removal encouraged scientiststo determine what was causing the females to breedso quickly after a calf had been lost or sold.Researchers found that calf removal stimulates arelease of hormones into the cowÕs blood, causingestrous to resume. It was also noted that thin cowshad lower hormone levels than cows that were notthin. It quickly followed that permanent calf removal(selling at an early age) could improve reproductiveperformance.Permanent calf removal is used today, particularlyin first-calf heifers, to dramatically reduce stressbrought on by nursing and poor nutrition. The calvesare typically sold at around 80 to 100 days of age. Inmost cases, this results in a high proportion of thefemales breeding in a 30 to 40 day period after saleof the calves. This form of calf removal is very effec-tive but results in selling calves at a young age and atlight weights, thus reducing income. Equally effec-tive alternatives, such as once-daily suckling or earlyweaning, allow calves to be retained to a marketableage and weight.With any calf removal procedure, the damÕs udderswill become full. Research on thousands of beefcows have found no permanent problems from over-fill of the udder, and milk production in later years isnot affected. Females will become nervous whenthey are away from their calves but will return tonormal behavior within a week of any treatment thatalters nursing stress.No Reduction in Calf PerformanceCalves that are weaned early and those sucklingonce a day show a slight drop in growth rates in thefirst 20 to 30 days of removal from their dams. Theyresume normal growth shortly thereafter, as long asadequate nutrition is provided. Their weights at 7months of age are similar to calves allowed to nursenormally. Calves that are removed from their damsin the 48-hour removal program show only tempo-rary weight reduction (about 10 pounds), but thisweight is recovered within 10 to 14 days.Deciding Which TypeRemember that in adequately nourished cows, it isnot necessary to remove the calf and reduce nursingstress. Calf removal is most often used to improvereproduction in females that are under severe nutri-tional stress. In these conditions, pregnancy rates will be extremely low without some form of calfremoval. The best management approach Ñ provid-ing adequate nutrition Ñ avoids the n

eed for remov-However, calf removal is sometimes used in maturecows that have begun to lose their normal pattern ofearly resumption of estrous activity. Some producersyoung females are slower to breed after calving thanmature cows, particularly when there is even a slightdegree of nutritional stress. If calf removal is needed,several factors determine which method should beusually the cows where calf removal is need-tive to even moderate nutritional stress.When feed resources are limited, some formof calf removal is a must if acceptable preg-nancy rates are to be realized in these cows. mothers Ñ Females with a BCS of at leastrespond well to 48-hour calf removal.Females that have a BCS of less than four(severe nutritional stress) will require themost aggressive forms of calf removal toachieve acceptable pregnancy rates.Calf age Ñ Do not remove any calf under 45days of age. Calves require adequate expo-permanent weaning can overwhelm a youngcalfÕs immune system and make it more sus-ceptible to disease. Calves older than 45 daysmay experience some illness but to a muchlesser degree than younger calves.Available labor Ñ Early weaning is laborintensive in the first 30 to 50 days of initiat-ing treatment. As calves get older, laborrequirements may decrease, particularly ifthe calves can be fed with self-feeders orturned out on pasture. Once-daily sucklingat least 45 to 50 days, after which the calvescan be returned to pasture with their dams.Compared to other methods, labor needs areminimal for 48-hour calf removal.The type of facilities needed Ñ For any typeof calf removal, shade is needed in hotweather, and shelter is required if cold andrainy weather is expected in the first days 3 after calves are removed. Provide feedtroughs so that rations can be kept clean andoff the ground. Fresh water is a necessity,and make sure that all troughs (water andfeed) are low enough to be reached by small-er calves. Fences should be secure enough toprevent calves from rejoining their dams.Nursing must be prevented to get the desiredresponse in the dams.Feed expenses Ñ Costs differ between treat-ments and are highest for early weaningcompared to once-daily suckling. Total feedexpenses will vary widely due to the amount of available hay or grazing, the amountof supplements that are needed when hayof days the calves are separated from thedams. Expenses are lowest for 48-hour calfremoval. The proximity of houses to the pens or pas-tures where calves will be held ÑConsidera-tion should be given to neighbors and familymembers. There will be considerable bawl-ing by the calves and their dams, which sub-sides after 4 or 5 days. This can be very dis-tracting to residents living nearby.Educational programs of Texas Cooperative Extension are open to all people without regard to race, color, sex, disability, rel