Estrous behavior, progesterone in peripheral plasma and milk in dairy goats at onset of breeding season

Influence of refeeding on production, blood biochemistry parameters, and reproduction in underfed Kacang goat does

This research aimed to investigate the effect of refeeding on production, blood biochemical parameters, and reproduction in underfed Kacang goat does. Twelve 2-3-year-old Kacang goats scored (body condition score [BCS]: 1-1.5) with poor body condition but appeared healthy, gave normal births 3-4 months before but no longer nursing their youngs, and anestrus were used in this study. The experiment consisted of 110 days with 14 days of adaptation period and 96 days of feeding treatment and data collection. After the adaptation period, the animals were divided into two groups (A and B), with six animals each. During the first 40 days (underfeeding period), they were fed with kangkong (Ipomoea reptans) straw at a level of 2% of body weight (BW). For the following 56 days (refeeding period), each animal in group A was fed at the level of 4% BW per day while group B was fed at the level of 5% BW per day consisting of 50% kangkong straw and 50% concentrate. Feed intake, average daily gain, body condition, and estrus were assessed in the period of underfeeding and refeeding. Blood samples were collected at the end of the underfeeding and refeeding period for blood biochemical parameter analyses. During the underfeeding period, the animals were anestrous and had poor body condition (BCS: 1.17-1.33) and high serum levels of cortisol, progesterone, and estradiol. Refeeding resulted in a significant increase in BCS (2.75-3.0), restoring estrous cycle, and reduced serum cortisol and progesterone level (p < 0.05). The Kacang goats had good compensatory growth. It could be concluded that refeeding at the level of 4-5% BW would restore undernourished goats' clinical condition, productivity, and reproductive performance after 8 weeks of refeeding.

The influence of some sample handling factors on progesterone and testosterone analysis in goats

This study validated the use of commercially available radioimmunoassay kits for measuring the circulating progesterone and testosterone levels of goats. Progesterone and testosterone levels were then assayed in plasma which was collected from 23 does and 8 bucks. Collections from each animal were divided into three sodium fluoride-potassium oxalate (F/OX), one heparin, and one EDTA tubes and also into a tube without anticoagulant. Plasma from an F/OX tube was separated immediately from the blood cells by centrifugation. Serum or plasma was also separated after storage for 24 hours with F/OX, heparin or EDTA anticoagulant at 22 degrees C or with F/OX at 5 degrees C. A significant decline in assayable progesterone occurred in samples stored at 22 degrees C with each anticoagulant used and in the serum sample. Samples stored at 5 degrees C for 24 hours with F/OX anticoagulant contained concentrations of progesterone which did not differ significantly from those in samples where plasma was removed immediately. Assayable testosterone did not change with the anticoagulant used or vary with the storage temperature when F/OX tubes were stored at 5 degrees C and 22 degrees C for 24 hours. Results indicate that sample storage does influence levels of measured progesterone but not testosterone in goats. Progesterone assay is best done on plasma which is immediately separated from blood cells or on samples which are stored at 5 degrees C.

Milk fat progesterone concentrations in goats and early pregnancy diagnosis

Blood and milk samples from foremilk during afternoon milking, were simultaneously collected from 285 dairy goats. In experiment 1, fiva cyclic goats were sampled daily for 21 days. In experiment 2, 280 females from 9 flocks were submitted to sampling 21 days after insemination. In addition, some milk samples were divided in two parts, after which one was frozen and the other kept at +4 degrees C until assay. Progesterone concentrations were measured in blood, whole milk and milk fat by radioimmunoassay. No difference in whole milk or fat progesterone levels was found between frozen and refrigerated milk samples. Milk butterfat progesterone concentrations paralleled those in plasma or whole milk throughout the estrous cycle and ranged from about 20 ng/ml at estrus to about 400 ng/ml in mid-luteal phase. The ratio of mid-luteal phase progesterone levels to those seen in the estrous period was over 20 in fat and in blood. This ratio was very much lower in whole milk. Consequently the determination of pregnant and non-pregnant goats from the samples collected 21 days after service was very much easier and accuracy was better when the progesterone content was assayed from milk fat than from whole milk. It was concluded that early pregnancy diagnosis in goats can be done routinely by determination of progesterone levels in milk fat.

Progesterone milk residues in goats treated with CIDR-G(®) inserts

Progesterone (P4)-impregnated intravaginal controlled internal drug-releasing devices (CIDRs) have been used worldwide for estrus synchronization in ruminants. CIDRs serve to place all treated animals in the luteal phase of the estrous cycle. The objectives of this study were to compare P4 concentrations in milk from normal reproductively cycling, CIDR-treated, and pregnant goats. CIDRs were placed in treatment goats on day 0 and removed on day 19. Milk was collected daily from day 0 to day 21 from control and CIDR-treated goats and for 5 consecutive days between 40 and 60 days of gestation from pregnant does. Milk P4 was plotted against time (in days) for each individual, and the area under the curve (AUC) was calculated as an estimate of total milk P4. The AUC(day 0-21) for control and CIDR-treated goats were 29.5 ± 11.9 and 33.7 ± 6.6 d·ng/mL, respectively (P = 0.77). The highest single-day and highest 5-day average P4 values for each animal were also compared among groups. Single-day peak P4 levels were 4.8 ± 1.5, 4.0 ± 1.0, and 6.0 ± 0.4 ng/mL for control, CIDR-treated, and pregnant goats (P = 0.42). The highest 5-day average P4 concentrations were 3.6 ± 1.3, 2.9 ± 1.8, and 4.2 ± 0.3 for control, CIDR-treated, and pregnant goats (P = 0.56). The results of this study show that intravaginal P4 CIDR devices inserted for 19 days in healthy goats resulted in milk P4 levels similar to or less than those endogenously produced during diestrus or pregnancy.

Milk progesterone profiles during anoestrus through to pregnancy in Greek dairy goats (Capra prisca): the effect of melatonin treatment and male introduction

Two groups of 10 lactating does were housed separately, in isolation from bucks. Does in one group (T) were implanted with melatonin; the second group (U) were not implanted. After 30 days, five implanted and five non-implanted bucks were introduced, singly, into both groups of females each day. Subsamples of milk were taken from the daily output of each doe on 3 days each week for progesterone analysis.

Mean milk progesterone concentration during anoestrus varied significantly amongst individuals (P < 0·001), but the difference between T and U groups was not significant (1·51 and 1·93 (s.e.d. 0·52) μg/l, respectively). Elevated progesterone levels, indicative of a short oestrous cycle and commencing days 2 to 5 after male exposure, were observed in most does. Mean progesterone concentrations were 9·9 and 9·6 (s.e.d. 1·32) μg/l in T and U does respectively. Most does showed a second short cycle starting at 12 to 18 days, (mean concentration 8·4 and 10·6 (s.e.d. 1·64) ng/l, respectively). Untreated does then returned to anoestrus until mated at 63·1 (s.e. 0·94) days after male introduction. In contrast, T does either became pregnant or had a normal oestrous cycle, followed by a repeat cycle or pregnancy (mean onset 21·7 (s.e. 2·22) days after male introduction). The mean time of effective mating for group T does was 37·3 (s.e. 5·91) days, 26 days earlier than for U does (P < 0·001). Mean progesterone concentration in early pregnancy was 65·7 (s.e. 5·78) and 67·6 (s.e. 5·41) μg/l in T and U does, respectively. Males did not become sexually active until after the onset of luteal activity in the females, although treated males were earlier than untreated. There were no significant differences in lactation pattern associated with the progesterone profiles in the two groups.

The introduction of males during late anoestrus initiates short luteal cycles. Only those does closest to onset of the breeding season, in this case induced by melatonin, continue to cycle normally and mating success may require early stimulation of sexual activity in males.

Effect of plane of nutrition on seasonality of reproduction in Spanish Payoya goats

The aim of this study was to determine if there is a seasonal pattern of sexual activity in female Payoya goats and if this seasonality could be modulated by nutrition. During the experimental period of 20 months, 43 non-pregnant adults goats were penned under natural photoperiod at latitude 37 degrees 15'N. At the onset of the experiment, the animals were allocated to three experimental groups differing in the level of nutrition and whether the animals were entire or ovariectomized does. The high nutrition group (H, n = 16 entire does) receiving 1.5 times maintenance requirements. The low nutrition group (L, n = 16 entire does) and an ovariectomized and oestradiol treated group (OVX, n = 11 ovariectomized does) received a diet supporting their maintenance requirements. The groups were balanced for live weight (LW) and body condition score (BCS) at the beginning of the study. In entire goats, oestrus was tested daily using aproned males, ovulation rate was assessed by laparoscopy 7 days after identification of oestrus and plasma samples were obtained twice per week for progesterone assay. OVX goats were isolated from the other groups and bucks, plasma samples were assayed twice per week for LH and there were four intensive sampling periods during the year to determine LH pulsatility. LW and BCS were recorded for all animals once a week. A clear circannual cycle in live weight change was observed in all experimental groups, being relatively stable or slightly decreasing in summer and autumn and increasing during winter and spring. The effect of exposure to high (H) rather than low (L) nutrition was to cause earlier onset of ovarian activity (5 versus 17 August; P < 0.05), and expression of oestrous (16 August versus 2 September; P < 0.01) and later cessation of reproductive activity (ovulation 11 February versus 17 January; P < 0.01). Consequently, seasonal anoestrus was 32 days shorter in does on the higher plane of nutrition (P < 0.01). The seasonality of reproductive activity was confirmed in the OVX does, with reduced LH concentrations during spring and summer, and increased LH concentrations in autumn and winter. There was no effect of nutrition on ovulation rate. These results demonstrate that the female Payoya goat exhibits marked reproductive seasonality which is modulated by nutrition but possibly not ovulation rate.

Assessment of progesterone concentration using enzymeimmunoassay, for early pregnancy diagnosis in sheep and goats

The objective of this study was to determine a value of serum progesterone (P4) concentration, assessed using an enzymeimmunoassay (EIA), for the early distinction between pregnant and non-pregnant ewes and goats. Adult, non-lactating ewes of Chios (n=53), Berrichon (n=30) and Sfakia (n=45) breeds were synchronized during the breeding season with progestagens and gonadotrophins and mated to fertile rams (Experiment I). Adult, lactating goats of Swiss breeds (Alpine and Saanen, n=104) and indigenous Greek breed (n=45) were synchronized during the transitional season with progestagens, PGF2alpha and gonadotrophins. Cervical artificial insemination (AI) with fresh semen was applied once, 42-44 h after sponge removal (Experiment II). Jugular blood samples were collected on day 19 after sponge removal (ewes) or on day 21 after AI (goats) and serum P4 concentration was determined by EIA. Progesterone concentrations >/=1.0, >/=1.5, >/=2.5 and >/=4.0 ng/ml were tested as indicative of pregnancy. Pregnancy diagnosis was verified on birth. In the case of sheep, using a discriminatory level of 2.5 ng/ml, overall accuracy of pregnancy diagnosis was 91.4% and predictive value of negative and positive diagnoses were 98.3 and 85.3%, respectively. In the case of goats, predictive value of negative diagnosis was 95.8 and 94.0% and predictive value of positive diagnosis 71.3 and 71.7%, for 1.5 and 2.5 ng/ml, respectively; overall accuracy was 79.2% using either level. The other discriminatory levels tested did not improve these results. A significant positive correlation was observed between P4 concentration and the number of lambs or kids born, and further analysis indicated that this relationship is not a simple linear function. Based on the results of this study, P4 concentrations of 2.5 ng/ml in the case of ewes and 1.5-2.5 ng/ml in the case of goats, determined with EIA, are proposed as discriminatory levels between pregnant and non-pregnant animals, at an interval of one oestrous cycle after service.

Concentrations of progesterone in milk from bottlenose dolphins during different reproductive states

There are few published reports of an alternative, less invasive method than blood sampling to obtain reproductive hormone concentrations from captive dolphins. The aims of this study were to: (1) validate milk as an effective alternative to blood plasma for determining progesterone concentrations; and (2) utilize milk samples collected frequently to obtain progesterone concentration profiles and determine reproductive status. During the course of this study 16 plasma/milk sample pairs were collected from four adult bottlenose dolphins to correlate plasma and milk concentrations of progesterone. Milk samples were also collected approximately weekly for 4-5 months during three independent lactational periods. Additionally, milk samples were collected daily for approximately 1 year during three other independent lactational periods. A highly significant correlation was found between progesterone concentrations in plasma and milk (r(2) = 0.91, P < 0. 01). Progesterone contained in milk whey, fat, and solids were 3.95 +/- 1.3, 8.5 +/- 1.1, and 52.0 +/- 0.6%, respectively. Progesterone profiles from milk samples collected from two dolphins during 1995 indicated pregnancies (with progesterone concentrations between 8 and 46.5 ng/ml) which resulted in parturition. High progesterone concentrations in a third dolphin that did not give birth indicated a possible pseudopregnancy or fetal resorption. A possible ovulation not resulting in pregnancy was evident in one female in 1998, follicular activity in another female in 1998, and a year-long anestrous period in the third animal studied in 1998. It is confirmed that dolphins can become pregnant while lactating and that the approximate time of conception is identifiable in milk profiles, illustrating the potential application of this method in pregnancy detection and reproductive monitoring.

Pregnancy diagnosis in dairy goats using progesterone assay kits and oestrous observation

Two qualitative on-farm milk progesterone test kits were used for early pregnancy diagnosis in goats. One kit was based on latex agglutination (LA) and the other on enzyme-linked immunosorbent assay (ELISA). The accuracy of early pregnancy diagnosis by these two methods was compared with the accuracy of oestrous observation (OeO) and the level of plasma progesterone measured by radioimmunoassay (RIA). Dairy goats (n = 73) from a single herd were used for collection of milk and blood samples 20 days after breeding. Ultrasound examination 50 days after mating found that 49 (67%) goats were pregnant, and 24 (33%) were not pregnant. Using ultrasound as a reference method, the accuracy of early pregnancy diagnosis by RIA and OeO was 92% and 86%, respectively, and for non-pregnancy 100% for both RIA and OeO. The accuracy of early pregnancy diagnosis by ELISA and LA was 82% and 79% and for non-pregnancy, 88% and 100%, respectively. The kappa-statistic for RIA, OeO, ELISA and LA was 0.93, 0.84, 0.77 and 0.73, respectively. It was concluded that LA and ELISA tests can be used for early pregnancy diagnosis in dairy goats. However, in the herd studied, early pregnancy diagnosis by OeO was as good as that achieved with progesterone determination using the kits.

Secretion of progesterone and 20 alpha-dihydroprogesterone during the estrous cycle in goats

The secretion of progesterone and 20 alpha-dihydroprogesterone (20 alpha-DHP) during the estrous cycle and the effects of prostaglandin F2 alpha (PGF2 alpha) and 20 alpha-DHP on the secretion of these two steroids during the midluteal phase in goats were studied. The mean progesterone concentration in the peripheral plasma was extremely low (< 0.01 ng/mL) on the day of estrus. The concentration increased to a maximum (7.80 ng/mL) on about day 10 after estrus, and decreased rapidly during the last 3 days of the cycle. The plasma concentration of 20 alpha-DHP also was low (0.86 ng/mL) on the day of estrus, but increased gradually after estrus and decreased gradually in the last 5 days of the cycle (to 3.22 ng/mL). The ratio of progesterone to 20 alpha-DHP was > 1 after day 2 of estrus, but decreased and fell to < 1 during the last 3 days of the cycle. An injection of 3 mg of PGF2 alpha decreased the secretion of progesterone within 30 min, but affected the secretion of 20 alpha-DHP little until 2 h. The ratio of progesterone to 20 alpha-DHP fell to < 1 after 24 h. Three of the five goats given such an injection came into estrus within 2 days, and the other two came into estrus within 3 days. An injection of 15 mg of 20 alpha-DHP did not affect progesterone secretion or the estrous cycle length. These results indicate that in the goat after estrus, there is much 20 alpha-DHP in the peripheral plasma. Progesterone may be catabolized to the biologically inactive steroid, 20 alpha-DHP, during luteolysis.

Time-resolved fluoroimmunoassay of progesterone in milk

A direct, solid-phase, time-resolved fluoroimmunoassay for progesterone in cow's and goat's milk, using europium-chelate-protein A as a label, is described. The coefficients of correlation with the results by RIA were 0.987 and 0.989.

Concentrations of oestradiol-17 beta in plasma and milk and progesterone in plasma during the oestrus cycle and in early pregnancy in goats

Pre-ovulatory peaks in oestradiol-17 beta concentrations were observed on days 1 or 2 and post-ovulatory peaks between days 4 and 7, both in jugular venous plasma and defatted milk, day 1 being the day of the onset of oestrus in the goats. Mean values of the magnitudes of these concentration peaks and of their timing (relative to oestrus) during the oestrus cycle did not differ significantly (P greater than 0.05) from those when the goats were mated and became pregnant. Pre-ovulatory oestradiol-17 beta peaks were invariably greater than the corresponding post-ovulatory peaks, as were peak concentrations in plasma relative to those in defatted milk collected on the same day. Mean intervals between the pre- and post-ovulatory peaks in oestradiol-17 beta concentrations were respectively 4.2 days for plasma and 4.0 days for defatted milk. Concentrations of oestradiol-17 beta in jugular venous plasma and defatted milk were strongly correlated: rank correlation coefficients for the three goats studied were 0.871, 0.668 and 0.739. It is suggested that in goats, as in cattle, ovarian follicular oestradiol-17 beta secretion approaching pre-ovulatory level is restored by 4 days after oestrus and its rapid decline after this time may be due to the inhibitory influence of the rapidly rising plasma progesterone concentration.

Induction of oestrus in Saanen goats at early breeding season by intravaginal progesterone sponges (MAP) or by prostaglandin F(2)alpha injections. Effect on different age groups

Twenty-one maiden and 29 pluriparous milking Ankara Saanen goats received either two i.m. injections of PGF(2)alpha (n=25) or intravaginal MAP sponges (n=25) early in November at the start of the breeding season. About twice as many pluriparous goats as maiden goats exhibited estrus after either treatment (87% vs. 47%). Breeding after this induced estrus caused pregnancies in 62% of the pluriparous goats, but only in 24% of the maiden animals. Maximal concentrations of progesterone were reached 11 days after the start of the MAP treatment. Progesterone declined to basal levels two to four days after sponge withdrawal. A significant slower progesterone increase also resulting in lower maximal concentrations could be observed in maiden goats. Luteolysis was evident in all animals within 24 h after PGF(2)alpha injection. Nine goats (six maiden and three pluriparous) did not exhibit Heat after the second injection and showed only a slow increase of progesterone. It seems that noncyclic animals are less sensitive to MAP treatment than to the first PGF(2)alpha injection. Goats at the beginning of the breeding season may react after a premature interruption of corpus luteum function (after second PGF(2)alpha injection) with delayed or inadequate follicular function.

Milk progesterone for pregnancy diagnosis in dairy goats

Factors affecting progesterone concentration in milk of lactating dairy goats and use of this milk for pregnancy diagnosis were studied. Radioimmunoassay was used to assay progesterone in milk. Mean milk progesterone (ng/ml) +/- standard errors of 6 pregnant does for first, composite, and last milk were 9.9 +/- 2.0, 18.2 +/- 3.5, and 21.7 +/- 4.1. Correlation between milk fat and progesterone in composite milk was low (.11). Composite milk samples from 4 nonpregnant does were obtained daily throughout the estrous cycle. Milk progesterone (ng/ml) was 1 to 2 at estrus, rose to 5 to 12 within 2 to 5 days, reached a plateau at 15 to 25 in the middle of the estrous cycle, and then dropped to low concentrations again at 3 to 5 days before the next estrus. Milk progesterone also was used to diagnose pregnancy in 72 does. Forty-two does were diagnosed pregnant by high progesterone; 36 of these does later produced kids, and 5 other does aborted in various stages of pregnancy. Of 21 does diagnosed not pregnant with low progesterone, 19 does were not pregnant by either return to estrus or lack of parturition in the spring. All three incorrectly diagnosed does were problem breeders. Nine does with intermediate milk progesterone were classified questionable. Milk progesterone can be used to provide an early indication of the pregnancy status of does.