LIBRARY JUL 1a 1974. REPRODUCTIVE EFFICIENCY IN Texas A&Nl University I 8-113 MARCH I97 64W The Texas A&M University System, The Texas Agricultural Experiment Station, J. E. Miller, Director, College Station, Texas CONTENTS Poor reproductive performance, long a problem of Angora goats under Texas range conditions, was studied to determine the nature of the problem and possible remedies. The basic reproductive phenomena of the Angora goat were re-analyzed. Since Angora goats are sexually active only during the fall seasons, they reach puberty either as kids at 7 to 9 months or 1 year later as yearlings. Only well grown out kids will exhibit sexual activity their first year, and these should not be used for breeding. The estrus cycle is approximately 20 days with an estrus period lasting approximately 1 day. The mean gestation length is 149 days. In most flocks a single kid is born per year, but twin ovulation or twin births may predominate in well-developed does in good condition. Ovulation and birth rate are closely related to weight of the doe at breeding. Birth weights are generally in the range of 5 to 7 pounds, but values above and below this are common. Major causes of loss in reproductive effi- 2 SUMMARY Summary ......................................................................... -- Introduction ............................... H}. ................................. -- 1 Basic Reproductive Phenomena ............................... ..g Age of Puberty ....................................................... Q Breeding Season ....................................................... .. Length of Estrus Cycle ...................................... "g Length of Estrus Period .................................... if Gestation Length .................................................... Ovulation or Kidding Rate ................................. .. Fetal Development and Birth Weight ............... Sources of Loss in Reproductive Efficiency ........... Failure to Show Estrus or to Ovulate ............... Failure to Conceive ............................................... Abortion ................................................................... .. Cause of Abortion ................................................. Recommendations to Reduce or é Prevent Abortion Losses ................................ ..j Death Loss of Kids .................................................... Predators .................................................................. .. g Cold Stress .............................................................. .. Birth Weight .......................................................... Opportunities to Extend Kid Crop ........................ .. Management Routine .......................................... ..: _Mating at the First Versus the Second I or Subsequent Estrus ..................................... ..1 a Literature Cited .......................................................... .. c ciency are failure of the doe to show estrus and o . and death loss of the kids produced. Other é of loss are failure of conception and abortio l failure to show estrus is explained almost total‘ lack of development, which may be corrected by y agement factors associated with improving the ani environment. Death losses of kids tend to be f ated with low birth weights of kids born of ,g undernourished does, cold stress at kidding or i tors. A high percentage of multiple births contri‘ to increased death loss of the kids, but the-o net reproductive efficiency is generally improv multiple births. Failure of conception and ai apparently have complex physiological explana Angora males normally act to terminate anes the female. This phenomenon can be used to im reproductive efficiency by synchronizing matin kidding in Angora does and also by permitting _ of mating in relation to initiation of estrual i RODUCTIVE ICIENCY do»; goat production has been an important I in Texas since the goats were introduced in Texas normally produces 96 percent of the U.S. ' supply which represents 60 percent of world tion. Numbers of goats have fluctuated widely i, e years because of the highly variable mohair i. and the influence of this variability on the g for replacement animals. The present popu- (1972) of approximately 1.5 million is the lowest since 1920. However, favorable mohair prices yekindled an interest in this industry. At present i» the Angora goats in Texas are in the Edwards u where the industry began. Before losses to :ry animals became so severe and before the market break in 1964, large numbers were also y in other areas such as the Grand Prairie and Timbers (Central and North Central Texas) ‘ they were used to an advantage in land clearing h control. a reproductive efficiency has always been a o . No reliable statistics on the kid crop are le, but values range from a low of 0 to a high 100 percent. Although kid crops as high as cent are very rare, those as low as zero are not mon in the areas where predation is a problem. erage kid crop weaned is probably in the range to 60 percent, but the potential is more than " cent under favorable conditions. y high reproductive rate is important because e sale value of the kids produced, (2) it permits ustry to respond more rapidly to changes in ively, professor, The Texas Agricultural Experiment ', San Angeloyand sheep and goat specialist, The Texas ural Extension Service, Kerrville. ngolq (i0 ats MAURICE SHELTON AND JACK L. GRoFF* demand for mohair, (3) it facilitates improvement through providing a greater selection differential and (4) it permits improved mohair production (both quantity and quality) through lowering the average age of the flock. As goats become older, both the quantity and quality (fiber diameter) of mohair de- teriorates; thus, if the total goat population of the State remains stable, the average age is a direct func- tion of reproductive rate. i BASIC REPRODUCTIVE PHENOMENA An understanding of the basic reproductive phe- nomena of Angora goats is necessary to improvement of reproductive efficiency. Age of Puberty Age of puberty is the initial or minimal age at which the animal becomes reproductively active—does start ovulating and are capable of becoming pregnant; males are capable of'siring offspring. Angora goats are highly seasonal, and they reach puberty either during their first season at 6 to 8 months or l year later at approximately l8 months. Individual well- developed kids will reach sexual maturity their first season. It is not recommended that they be bred or used for breeding their first season. However, to prevent the occasional breeding of doe kids, they should be separated from mature animals during the breeding season. Since kids require or deserve special treatment, they should be managed separately through- out much of the year. Many animals will not breed satisfactorily as yearlings to kid at 2 years, but this failure is more a result of lack of condition and de- velopment than of age. The Breeding Season Angora goats are seasonally polyestrus; that is, they are seasonal breeders, and the females have re- occurring estrual periods during the season if they are not bred. Angora goats have not been widely studied in this respect, but many other species, including sheep, have been; it seems safe to interpolate across species in this respect. The phenomenon of seasonal breeding is known as photoperiodism, or response to the length of the daylight period, and is found in many plants and animals. In sheep and goats, the number of hours of darkness appears to be the con- trolling factor. The Angora goat is somewhat unique for domestic animals in that both the males and females are seasonal. The mating season of the male is easily detected by the characteristic odor and rutting activities. The Angora is also unique in that the females do not normally start cycling until they are stimulated by the presence of the male. Later in the season other stimuli can serve this same purpose. An- other unique feature is that the female does not first exhibit a silent estrus (ovulation without showing estrus) as do most other ruminants. Satisfactory results usually can be obtained from matings from the first of September through Decem- ber. Many individual does will breed as much as 30 days earlier or later than this. Length of Estrus Cycle The length of the estrual cycle is reasonably well documented. Typical estrual cycles of individual does are 19, 20 or 21 days. Shelton (1961) found the aver- age cycle length to be 19.5 days, while van Rensburg (1970) suggested a value of 20.6 days. The data on which the 19.5 estimate was obtained are shown in Figure 1. The values 14 to 17 may reflect abnormal cycles; if these are removed, the two estimates are almost identical. 30-1 *1 25- ,7— 1% 3 20— “6 _§ 15- E 5 Z 10-1 5- nnfinn H "14 15 16 17 is 19 20 21 22 Number of days Figure l. Length of estrus cycle in Angora does. Length of the Estrus Period The length of the estrual period has not .9 However’ extensively studied in Angora does. Rensburg (1970) arrived at an average length hours, which is shorter than in other species s V; sheep. Data of this type have not been tabula the United States, but observations indicate that or most of the does will be» in estrus for 2 con days. This would be expected in the case of of the does exhibiting a 22-hour estrus period. duration and intensity of estrus probably _wo somewhat longer at estrual periods subsequent first. If van Rensburg’s data were based on d g at the first estrus, this might contribute to an e? of somewhat shorter period than expected. Gestation Length The gestation length of Angora does is wel mented with Shelton (1961) reporting an ave 149.2 days (Figure 2) and van Rensburg (1970) If ing 149.4 days. South African researchers r a range of 143 to 153 days; however, gestation of less than 140 days were deleted and such l tions were recorded as abortions. Twin 'A normally dropped approximately 1 day earli i‘ singles. ; Ovulation or Kidding Rate _ The important contrast in Angora goa " tween the nannies that raise one kid and th raise none, but the potential for twinning 1201 H 100- m ‘l 1 5 3 g 80< 3 8 B 60- 7 a l'l Q 2 9 z 40* _ 20- H ; Meizmn a » a :::§§§§§9§$§§ Length of gestation in d Figure 2. Length of gestation of Angora does based The ovulation rate refers to the number of iova liberated from the ovary at a given estrus Except for the possibility of identical twinning, llation of two eggs or ova is necessary for twin ‘but the ovulation of two ova does not insure rth as one of the pair may not be fertilized i; resulting zygote may not‘ survive to term. V twinning has not been demonstrated or _ ted with Angora goats; if it occurs, it is of frequency. With other species, such as the fvulation rate is largely determined by breeding ‘g ces between breeds or selection within breeds), of the year and size or condition. Season of A is not an important consideration since normally are not bred outside the fall season. the ovulation rate for the various months ptember through December has not been observations suggest that this is not an im- l source of variation. and development of the doe seem to be the f. urce of variation in ovulation or kidding rate. é dy by Shelton and Stewart (1973), 244 does lughtered and the ovulation rate recorded. Of 3| ber, 25 (10.2 percent) had not ovulated, 170 cent) had single ovulations and 49 (20.1 per- d ovulated two eggs. However, the ovulation - 'ed greatly between groups of does. The rela- I; ovulation rate to size is shown in Figure 3. Did not ovulate D Ovulated a single ovum Twin ovulations M .0. raummwsat-mw .Awe-..~.~.¢...-.~w-...0e-a,.»et » <1 lv- ‘,;;1 -.»- ‘ y,» k-t-u. - 0.00 - 0.00 The ovulation rate indicates the potential kidding rate, but in practice the kidding rate always will be somewhat below this potential. Fetal Development and Birth Weight In a study of progesterone content of the ovaries (unpublished data, The Texas Agricultural Experi- ment Station), Angora does were sacrificed at various stages of gestation (30-141 days). Fetal weight and crown-rump length were recorded on 80 embryos. The crown-rump length measurements (body length from the crown of the head to tail setting) are essen- tially linear (Figure 4). From this relationship, fetal age can be determined-—either approximately from the graph (Figure 4) or more accurately by calculation. Fetal weight is highly correlated with age, but this relationship is curvilinear instead of relatively linear as with fetal length (Figure 4). Actually the increase in fetal weight is geometric in nature, being very similar to the theoretical curve assuming a constant and unlimited rate of cell division. If these values are plotted on log paper, the result is almost a straight line up to approximately 130 days. This shows the relatively small amount of nutrients required for fetal development before about 9O days and during the period of rapid growth from 90 to approximately 130 days. After approximately 130 days, the rate of fetal growth begins to slow or deviate from the theoretical Figure 3. Breeding weight of does in pounds. - 0.00 - 0 00 60-10 A 70-00 Weight of does, pounds 30-90 ' 1 00+ -l 7 2O '- 19 - 18 t. Fetal weight in pounds ---->- - 6t 17 - 16 - 15 - - 5 I 14 - 13 - m 8 12 _ Regression of fetal length _ 4 E g on age (in inches) ——‘~ é 4' .5 .5 11 ' E i, 1o - TE» 5 i I 9 - -' 3 - E ‘E u 8 - "- 7 i- 6 " " 2 Figure 4. Rate of fet 5 _ velopment. (The age ~ fetus or embryo can ‘ 4 __ culated with reasona, curacy by dividing the 3- _ 1 length (crown-rump I in inches by .149 an 2- ing 30 to give the -‘ \ 1 days.) o L I l l l l I l l | | g g 30 40 50 60 70 80 90 100 120 130 140 Birth Days of gestation or fetal age growth curve. This presumably represents some de- gree of limitation due to undernutrition, uterine crowding and so forth. Thus, final or birth weight will be dependent 0n such factors as sex and type of birth as well as on size and nutritional status of the dam. Under normal or optimum conditions, the rate of fetal growth during the last 2 weeks appears to be approximately 0.1 pound daily. Thus, in extreme cases birth weights could vary as much as 3 pounds below the 6.5 pounds plotted in Figure 4. In actuality most kids weigh between 4.5 and 7.5 pounds. The influence of sex and type of birth on kid weight is shown in Table 1. SOURCES OF LOSS IN REPRODUCTIVE EFFICIENCY Successful reproduction consists of a number of discrete and largely independent processes. These are occurrence of estrus and ovulation, conception, em- bryo survival to and through parturition and survival of kid from parturition to weaning. ' TABLE 1. INFLUENCE OF SEX AND TYPE OF BIRTH ON WEIGHT OF KIDS Sex and type ' No. Avg birth of birth kids weight-, lb. Single male 413 6.47 Single female 347 5.99 Twin male 350 6.05 Twin female 368 5.46 6 ~\ Shelton and Stewart (1973) attempted to par the losses in reproductive efficiency of Angora g The results are shown in Table 2; however the; apply only to the peculiar set of conditions inv Death loss of kids was the single largest (Table 2). Although only 22 percent of the of s. TABLE 2. SOURCE OF LOSSES IN REPRODUCTIVE EFFICIE ANGORA GOATS Cumulative Loss, Per ~i Reproductive phase °/° Range doe lat" 1. Failure to ovulate 10.7 o.o-2a.6 10.7 I (did not show estrus) 2. Did not conceive 12.5 (does not pregnant at 25-30 days) 3. Ovum not fertilized 19.9 (ovulation points not represented by embryo at 25-30 days) 4. Does conceiving but 8.9 failing to kid 5. Embryo loss 12.2 l7» embryos at slaughter, less number of kids at parturition) 6. Does kidding but 22.0 failing to raise kid 7. Death loss of kids 32.1 5.9-23.2 23.2 (1 11.0-25.0) (0.20-16.7) 32.1 (4.5-29.4) (4.3-50.0) 54.1 13.7-66.7) I 'ds, 32.1 percent of the kids were 10st. This s a heavier death loss among twins than _, The major causes of losses in Angora kids “redators, damaged udders of does and general ‘ss in twin born kids. However, two of the causes of losses (predation and the large number kids) may be unique to the particular condi- xi» this study. Most of these data were collected skidded in confinement, but no effort was I to assist or artificially rear kids. Kidding in ement does not automatically reduce death ] except in those cases where shelter from in- 3| weather is provided. though the combined data indicate death losses to be the major problem, this was not true l group of nannies. Thus, in individual flocks i phases in the reproductive process may be the " points of loss. fbortion, as indicated by losses from 30 days to E1 was the least important sources of loss (8.9 "t of the does). However, major losses from ion tend to occur as abortion storms or outbreaks 2 are sporadic in nature; such were not encoun- fin any of the experimental groups in this study. abortion should not be ruled out as a source in reproductive efficiency. It is possible that vbortion syndrome is represented in part of the noted as failure of fertilization or conception. j nannies that abort habitually show reoccurring I egular heat periods. ese data, plus observations, suggest the follow- roblem areas in reproduction in Angora goats: ailure of estrus and ovulation due to under- pment of the female, (2) lack of strength and jg vigor in breeding males due to undernutrition, rtion and (4) death losses of kids. p». possible means of alleviating losses from f‘ sources are presented. ‘(re Io Show Esfrus or to Ovulate I ailure to show estrus or to ovulate is one of the causes of loss in reproductive efficiency in Angora I In the study by Shelton and Stewart (1973), percent of the goats did not cycle, but among i. ious groups this ranged from 0 to 28.6 percent. ing that mating is attempted only in the fall ‘jthese goats normally would be cycling, a failure e is almost certainly caused by a lack of size and opment. This relationship is shown in Figure 3 able 3. Generally it is assumed that an Angora ould weigh at least 65 pounds (shorn body 5 t) before a reasonable level of reproductive effi- can be expected. This is modified somewhat Q of the doe. A yearling doe will more readily l‘ at weights below this than will aged does that riously under weight. The enormity of the em is apparent—more Angora does in Texas TABLE 3. INFLUENCE OF BREEDING WEIGHT ON NUMBER OF KIDS BORN AND RAISED IN TWO RESEARCH FLOCKS Sonora data McGregor data Weight range (shorn body wt % kids "/0 kids "/0 kids "/0 kids at breeding) dropped raised dropped raised Below 6O Ib. 52.2 47.4 76.5 58.8 6O - 70 83.8 78.7 101.9 62.1 70-80 91.6 85.2 117.3 81.2 8O - 9O 88.9 81.0 143.2 114.8 9O - lOO 96.2 88.7 147.4 116.8 Over 100 115.4 113.8 Summary 74.7 69.1 128.1 94.6 weigh below 65 pounds than above. The solution is difficult. The high level of mohair production of the Angora goat ensures that this animal is almost always in nutritional stress under typical range condi- tions (the nutritive requirements of Angora goats have been reviewed by Huston, Shelton and Ellis, 1971). Management practices which contribute to better de- velopment are proper stocking rate and other range management practices, parasite control and supple- mental feeding. If optimizing these practices fails to result in an adequate level of reproduction, it may be necessary to relax somewhat the selection for ex- treme mohair cover or fleece weight. Perhaps the best way to accomplish this is to select for the animal which performs well under the conditions in which the animals are to be maintained. Failure to Conceive Lack of conception was implicated in failure of 12.5 percent of the does or 19.9 percent of the ovum ovulated (Table 2). This varied from a low of 5.9 to a high of 23.2 percent of the does. These values were somewhat higher than expected, and the research itself does not directly suggest the reason. Other observations suggest three factors as the primary causes for this loss. The difference between the per- centage of does that do not conceive and the percent- age of unfertilized ovum suggests that the loss is much higher in twin ovulations. A portion of this is obvi- ously due to chance. The likelihood that any given ovum will become fertilized is less than 100 percent. If it is assumed that the chance is 80 percent, then the chance of both eggs of a twin ovulation would be 64 percent. However, if only one egg becomes ferti- lized, the doe will not return to estrus in the next cycle. In twin ovulations, there may be considerable disparity in the time at which ovulations occur. Other factors probably contributing to a failure of concep- tion are a lack of libido or mating vigor of the male. Sterility is not a major problem among Angora males that are strong and have sufficient mating vigor (Figure 5). However, lack of strength is a distinct problem in poorly nourished, unthrifty or under- developed males. In the extreme cases of poor de- velopment, the males will not be sexually active or will not show a rutting season. Some apparent cases 7 Figure 5. Strong, well-developed males at breeding time are a necessity. ldeally these should be the type of goat that can main- tain itself in strong condition under actual production conditions without excessive supplemental feeding. of failure of conception may be attributed to an early expression of the abortion syndrome. Where numbers permit, culling of dry does is indicated (Figure 6). Culling of dry does will usually improve kid production in subsequent seasons. How- ever, in times of favorable mohair prices, it may be desirable to keep these does because the value of the hair produced may more than make up for the gen- erally small difference in kid production. The choice of culling or keeping dry does provides one means of adjusting numbers in response to mohair prices. Abortion Although not true in the reported data, abortion is an important source of loss in reproductive effi- ciency in Angora goats. Losses which may be related to the abortion phenomenon may occur in three forms. The most important of these occurs as abortion storms in which a large number or a high percentage of the does abort within a few weeks. The majority of these losses occur in close proximity to. 31/2 months of gesta- tion. Abortion in range Angora goats occurs infre- quently, but the presence of aborters in the flock can be ascertained from observing blood-stained hair on the tail or around the vagina. Its presence is almost a sure sign that abortion has occurred. However, it is important that blood stains be distinguished from urine or fecal stains. Most producers will experience some losses from abortion, but in most flocks this loss is small except in so-called abortion storms. In the experimental flocks owned by The Texas Agricultural Experiment Station, known abortion 8 l t] % Does kidding so a h- % Dry does $ 7O ' .~ r- 3 .> .15.” 6° l a 2 .2 5o - Q) U C CU E 40 - - 3 E Q. g 3o - ‘a 3 ‘U 2 20 1 Q. U I 10 - 0 Does which kidded Dry does Figure o. The relation of one dry season to breeding perfo i‘ the fol lowing year. losses normally run O to 3 percent, but in one abortion losses amounted to approximately l6 pe I In one problem flock annual losses of 16 percent incurred over a period of years, and losses much than this have occurred in problem flocks in it years. South African mohair producers have a ently suffered even more serious losses. Van H of (1964) reports losses as high as 6O percent. A form of loss is a low incidence of repeat abort" which the same doe aborts year after year. Alt normally of low incidence, the number could up to become an important source of loss if does are not identified and removed. The s expression of this problem is a number of dryj that seemingly have adequate size and develop to have bred. These does either fail to conceill lose the embryo very early after conception.)g; large mature or aged doe which does not kid be considered a suspect. Except as explained by” size or stress, the level of abortion is likely toi l with increasing age of doe. Cause of Abortion Attempts to explain abortion in Angora; have had only limited success. Infectious age not thought to be a primary cause of aborti future research may prove this to be in errorg; most definitive study of abortion is that repo van Rensburg (1970), but his work was large“ cerned with repeat or habitual aborters, whe loss in the United States is from the sporadic . The causes of these appear to differ somewhat wing to the actual time in which abortion occurs, e basic defect of the goat is probably the same filth. l e only consistent difference noted between the and aborting goat is the size of the adrenal or adrenal steroid production. Since the ‘a1 gland plays a significant part in initiating al parturition, an altered adrenal status as a appears to provide a workable hypothesis for 'on in goats. A high cortisol level inhibits hair , and van Rensburg postulates that in breeding e extremely high level of hair production, man lected for a relatively low level of adrenal func- South African goats which as a group have a abortion history have smaller adrenals than Angoras (van Rensburg, 1970). g normal functional adrenal is necessary to p: in pregnancy, and abortion in goats is preceded lrecipitous decline in cortisol levels in the blood, a can be considered to be adrenal fatigue. Actual i» ition is normally kept in check by the secretion tisol by the maternal organism. Thus, in the 2, - of a high level of maternal adrenal function, ital adrenal increases its output of cortisol, and l-ture parturition occurs. In Texas most abor- iroblems center around precipitous outbreaks at ' 3% months of gestation. This initial abortion lely limited to does of small size, to stress situ- or to a combination of these (unpublished otein deprivation also can bring about an in- ' in abortion. Although no detailed observations enal function have been made in the United 7. Supplemental ,at critical times may e difference be- A good kid crop and l. For good reproduc- ormance, the most riod is from ap- fly 100 days of i through kidding. States, general observations are not inconsistent with a theory of abnormal adrenal status. Any type of stress situation would be expected to compound adrenal insufficiency. Protein deficiency results in a decrease in adrenal size or decreased adrenocortical activity. The time in which most abortions occur coincides with the stage of rapid fetal development. High mohair producing goats are almost always deficient in protein; this is particularly true in late gestation (Figure 7). Thus, many very small goats will abort at this time even in the absence of specific stress (Figure 8), but abortion among others likely will occur only if they are subjected to stress at this critical stage. Oneof the most common forms of stress is feed deprivation brought on by factors such as movement of the flock or snow or ice cover. Abor- tion outbreaks will occur a few days following these stress periods and not at the actual time of stress. Several attempts have been made to study flush- ing of Angora goats. These studies have generally shown that it is possible through feeding at breeding to get several small does to breed that would not other- wise do so, but unless this superior care is continued throughout gestation, many of these does will fail to raise a kid either through abortion or loss of the kid at or subsequent to parturition. In a broad sense, abortion in Angora goats is inherited since this animal aborts, whereas other types of goats do not have this tendency to any significant degree. However, there is no evidence that any specific gene or genes, independent of other important traits, contribute to this problem. Evidence suggests that genetic selection for a high level of mohair production has altered the metabolic priorities to the extent that % l % % Does Does Dry kidding aborting does 1001 90- 80- 70- m 60-i u: O "U g 5o~ ‘F’ “c”: ‘I’ 5 40- o F» fl- "h. 3w 17-361" 20“ 10- O Less than 60-80 More than 60-lb. lb. 8O lb. Breeding weight Figure 8. Reproductive performance of 218 does in the experi- mental flock for the 1969 kidding season. Fifty-six percent of the does that mated in the below-éO-pound weight class aborted as compared to 11.5 percent for those weighing 60 to 8O pounds and 0.0 percent for those weighing above 80 pounds. fiber production takes precedence over other body functions, including reproduction. Abortion is only one expression of this phenomenon, and altered adrenal status, if such is the explanation, is merely the physiological means by which this is accomplished. As support for the theory of altered metabolic priorities, only relatively high-producing or well- covered goats show a marked tendency to abort, and those that subsequently do abort generally will be found to have been heavier producers early in life. This situation presents a paradox for the breeder in that it suggests selection for reduced hair production as the solution, but it would be difficult to justify 10 this approach. A preferable situation is that in w metabolic priorities are such that the animals prodi mohair to their maximum capability when nutri are available but do not sacrifice reproduction or r own survival for this purpose. Indications are individual animals do meet these specifications. T selection for desirable mohair traits still appears be indicated, but breeding males should be kept L only those does that have good reproductive his This approach would require some kind of re system which many producers will be unwilling} maintain. The next alternative is to select str; vigorous males that have been raised under ac production conditions. This should go a long” toward eliminating abortion as a serious problem. Recommendations to Reduce or Prevent Abortion Losses 1. Select as breeding stock, especially males, r those animals that remain strong and vigorous up the actual conditions in which the flock is to,“ maintained. 7 2. Do not breed young and underdevel‘ females unless feed conditions are likely to sup good growth and development to kidding. The ' native to this may be to initiate an abortion hi I which will be continued throughout the life of a doe. ~- 3. Prevent any undue stress, particularly V tional stress, after about the third month of pregn j 4. Identify and sell or remove to a separate 5 any does that abort. In no case should a male be kept from a doe with an abortion Ideally does which abort should be culled as th a tendency for abortion to become repetitive; times of favorable mohair prices, these does 1% be kept for mohair production, but preferably? should be maintained in a separate pasture from I all offspring are sold (Figure 9). l 5. Large, well-developed does that fail should be considered as potential early aborter" removed from the flock. ‘ DEATH LOSS OF KIDS Data indicate that death loss of kids is the ' most important sourceof loss (Table 2). In this 22 percent of the does lost their kid or kids. Al these data were collected under a specific set r ditions not likely to be duplicated in practice, losses probably represent a major source of loss‘ all except the very best of conditions. i Two of the major sources of loss are pr‘ g animals and cold stress. Closely following th‘ weak kids, poor mothering and bad udders ~ does (Figure l0). - I J___ Does I Does which I which kidded | aborted previous previous year I year u Influence of previous history on abortion rate in Angora hese data were taken from a flock which had an abortion ‘ In 1 year the aborting and kidding does were identified. 1 ing year the overall abortion rate was 16.1 percent. The “ kidded the previous year had an abortion rate of 12.3 A F. hereas those which aborted the previous year suffered an e-rate of 26.5 percent. Van Heerdon [1964] reported that ainst aborters in 10 flocks for a period of 5 years reduced on rate by as much as 8O percent.) ,ora kids are among the most susceptible to (n, as they may be killed by both small and _nivores, as well as by certain flesh-eating ‘There seem to be only two avenues of pre- Y this predation—either removal of the predator ection of the kids. If the kids are afforded on for the first few days, they usually can 7» tacks by the small predators such as raccoons, vultures. However, the larger predators such bcat or coyote will continue to kill, with the eadily taking adult animals. For this reason of the offending predator appears to be the Alternative. ss '11 or cold stress is doubtless a major source among does kidding on the range. Choice of 1 date or provision of some protection are o approaches to eliminating this problem. Protection may consist of shelter or a pasture with substantial natural protection for kidding. As the season advances, the likelihood of kids being lost due to cold stress decreases, but the likelihood of getting wind or moisture or combinations of these increases as the season advances through April. However, a combination of all three variables within any given 24-hour period seldom occurs after March 1. Birth Weight Underlying all causes of death losses of kids is the problem of birth weight and vigor of the kids (Figure ll). Factors affecting birth weight are pri- marily size of the doe and nutrition during late gestation. In cases of critical need, such as a pregnant doe subsisting on dry or cured forage, the addition of supplemental protein usually will provide a good response in birth weight and kid survival. When green forage is available to the doe, protein need should not be limiting. OPPORTUNITIES TO EXTEND KID CROP Producers who can devote time and effort to their flock probably can increase the kid crop well above the level most would consider acceptable. Some human effort would be required, and whether this would be profitable would be dependent on the avail- able labor supply and the value of the kids produced. At times when surplus kids are selling at or near their meat value, few people would find it profitable to devote additional effort to saving the kid crop; how- ever, when mohair is selling well and surplus goats are in demand, this may well be a good investment of producer’s time. Death loss of kids is probably the single largest source of loss in reproductive efficiency, and cold stress, predators, weak kids and poor mothering are the primary reasons for this loss. All can be over- come to some degree by supervised or confinement kidding. The phenomenon of male goats acting to terminate anestrus in the female at the start of the breeding season can be used to synchronize kidding in which as much as 75 percent of the does will kid within a 5-day period (Figure l2). Thus, the intense labor requirements for supervised kidding may require only a very short time. Generally this may be made to coincide with the period immediately after shear- ing when protection of the does from cold stress is needed. Consequently, a few days of close supervision may help to solve two of the goat producer’s most serious problems. The primary requirements are a limited amount of barn and shed space and provision of the labor required (Figure l3). Management Routine Does should be sheared approximately 2 weeks before the start of kidding. Until kidding starts, the ll does should be run in a small trap and brought into the barn as needed to provide feed and protection and to get the nannies acquainted with the manage- ment routine. Shearing a short time before kidding allows the does to grow some mohair cover and elimi- Males ._ .._ _ Females 100-4 / 80"‘ .5 .2 . a 6O 3 2 8 '6 S 4o- cf 20-4 l l l l L J Less than 4-5 5-6 6-7 7-8 Above 4 8 Birth weight of kids Figure ll. Relation of birth weight and sex to survival of Angora kids. 12 Figure l0. Well-dev Angora does on ra Edwards County. Int if sence of severe cold i at kidding or pr, losses, well-develop well-nourished Angor of the type shown A produce kid crops ap g ing 100 percent. i nates handling closer to expected date of kiddi this will usually trigger a number of parturi A heavy lactating doe grows very little mohair , time after kidding. ' During the approximately 5-day period; most of the kids are dropped, the does shou, observed almost constantly. About 200 does i group are the maximum that can be managed i, manner, since in synchronized kidding a larger ber of kids will be dropped within a short i of time. This will contribute t_o mismotheringt '1 errors in pairing by both the handlers and th themselves. As kidding occurs, the does and th should be moved to confinement quarters until ' be determined that all is well; following thii may go with a larger group. After the intense of kidding is over, the does and their kids turned to pasture, subject to the problems of; losses. Generally it is advisable to turn all pasture after the period of synchronized kid’, over because the remainder of the kids will be if over a long period of time. 7 For male synchronization to occur, severa; tions must be met. The first is that it must be the breeding season; that is, September or late f degree of synchronization will be greater if it a in the breeding season as many of the fem g eventually start cycling in the absence of second condition is that the does must ha maintained completely separate from the A cjDoeskidding Kidsdropped i! BE is ii i” b I it? 5% a L i E a E f; i é PE 23 = i: 355i Pi "i '1 ill ‘z ..- . .10. E n l“ "““""‘°‘°"°°°’.‘3I‘.2“£3£92°BERRSQKQQR%EQQSSQ££R%QE? TIME LAPSE IN DAYS Beginning 149 days from start of breeding season l2. Distribution of birth for 497 kids (1956-58 kid crops combined) from The Texas Agricultural Experiment Station, McGregor. ce the rutting season started. This includes “on by some distance since males on the other lithe fense will result in initiation of cycling in ‘s. The third condition for occurrence of a y; ee of synchronization is that the does be in vigorous condition. per an adequate number of active males are ith the does, the majority will show estrus oximately the eighth day. Thus, a peak of i, should occur at approximately 158 days after s were introduced. The occurrence of estrus r largely within a 3-day period, but kidding more dispersed because of variation in the of gestation. The concentrated period of i_ will usually last. at least 5 days. Producers be aware of this phenomenon of synchroniza- ‘i " [hgggh they dQ ngt intend [Q utilizg it in figutre l3. Eidding in ‘thbe lotivyjith kiphdingdboxepif The firms ifdenti- W‘ klddlng Progmm- 5Y_I1¢hr°n1Za"°n_°ft@f1 Ji§°?n'§"ii?;’ $031.55 ififimvvifilfsie Tmieifélneivq. Lsiufiiced ti’ e211’, 111' (W311 Whffn T10 €ff0rt 1S m3ld€ t0 brlng Ill years but ‘is not widely practiced at present because of the labor i This may be undesirabk because if unfavop requirement. However, the potential. for synchronization of kidding -ather Occurs at the Critical time, heavy kid suggests that producers might reconsider the possibility of providing supervision and protection at kidding. 13 losses will occur.i Producers should devise a method of managing the breeding stock to avoid this possible loss. Mating at the First Versus the Second or Subsequent Estrus Angora does differ from other ruminant species in a number of characteristics relating to reproduc- tion. Some of these were discussed in “Basic Repro- ductive Phenomena.” Most species do not show an active estrus at the time of the first ovulation follow- ing a period of seasonal or lactational anestrus. This ensures that they will not be bred earlier than the second estrus. However, Angora does do show an active estrus at this first ovulation, and in most, or many, situations they are mated at this first estrus. They have a higher ovulation and also a higher con- ception rate at the second estrus of the season (Figure 14-). Most comparisons have shown also that the ovulation rate at the third estrus is below that of the second. A good physiological explanation exists for the higher ovulation at the second estrus, but the apparent drop at the third estrus is difficult to explain. This may be simply due to a deterioration in the nutri- tional status as the fall season advances. These studies (Shelton, 1961a) have consistently shown a benefit of approximately 20 percent in potential kid crop from mating at the second estrus. However, the ovulation or kidding rates shown in Figure 14 are somewhat high for most Angora does. These data were collected on does maintained on the Station which were in a strong condition or a good nutritional state. In many commercial flocks, the question is not whether a doe will raise one or two kids, but none as compared to one. Field trials under these conditions generally have not shown a benefit from attempting to breed at the second estrus, but this practice should be con- sidered for flocks in strong condition. The mating of does at the second estrus may be brought about by exposing them for at least 10 days to a sterile male (vasectomized, epididymectomized or ridgling males may be used) followed by fertile males. The same phenomenon may be simulated by exposing the does to progesterone before the introduction of males. The expense and difficulty of this practice suggest that it will »not be widely used by commercial pro- 14 1.60 '1 , Actual estrual periods 1.50 - g _ _. _ _ Simulated second estr w administration of ~ g 1.40 - 3 O. G) g5 1.30 < , C .9 5 1.20 - 3 O 1.10‘ 1.00 - J, 0 t I 1 g 1st 2nd 3rd 5'" .- estrus estrus estrus 5’ Figure 14. A comparison of the ovulation rate at ‘first three“ periods of Angora does (number of observations equal 488; data represent a compilation of several experiments. In somef ovulation rates were observed by laporatomy or slaughter others are based on kidding data. In all comparisons co a also favored matings at the second estrus. The hormone tr‘ used to simulate second estrus consisted of daily iniecti‘ progesterone for 1O days). ducers; however, it may be refined in the fut 3 the point that it is more workable. i LITERATURE CITED Huston, J. E., Maurice Shelton and W. C. Ellis. Nutritional requirements of the Angora Texas Agr. Exp. Sta. Bu. 1105. Shelton, Maurice. 1961a. Kidding behavi Angora goats. Texas Agr. Exp. Sta. PR-2l Shelton, Maurice. 1961b. Factors affecting ki duction of Angora does. Texas Agr. Exp MP-496. Shelton, Maurice, and Joe Stewart. 1973. Par ing losses in reproductive efficiency in goats. Texas Agr. Exp. Sta. PR-3l87. Van Heerdon, K. M. 1964. The effect of g aborting ewes on the abortion rate in Angory J. ,South African Med. Assn. 35:19. i Van Rensburg, S. J. 1970. Reproductive phy and endocrinology of normal and habitually ing Angora goats. A thesis for Doctor of i nary Science, Dept. of Physiology, Fac Veterinary Science, University of Pretoria, P ' Union of South Africa. I I AGRICULTURAL EXPERIMENT STATION 0 THE TEXAS A&M UNIVERSITY. 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