Post partum ovarian activity and uterine involution in the suckled swamp buffalo (Bubalus bubalis)

Ovarian activity and uterine involution were monitored by rectal palpation, oestrus detection and plasma progesterone analysis from 3 to 4 days to approximately 150 days post partum in 38 suckled swamp buffaloes (Bubalus bubalis). The intervals from parturition to regression of the corpus luteum (CL) of pregnancy and involution of the uterus were 10 and 28 ± 6 (S.D.) days respectively. First detected oestrus and first elevation of plasma progesterone (> 0.7 ng/ml) occurred at 88 ± 26 and 96 ± 22 days in 8 and 12 buffaloes respectively. During the first 150 days post partum, 26 of 38 suckling buffaloes (68%) were acyclic (anoestrus) and of 12 animals (32%) exhibiting ovarian cycles, 4 were not detected in oestrus. The tentative diagnosis, based on rectal palpation, that CL were present between days 30 and 90 after parturition (without concurrent luteal levels of progesterone in plasma) suggests that confirmation should be by laparoscopy. It is concluded that a delay in the resumption of ovarian cyclicity post partum represents an important factor contributing to the prolonged calving to conception interval in the suckled swamp buffalo.     

The postpartum buffalo. II. Acyclicity and anestrus

Prolonged postpartum acyclicity (absence of ovarian cyclic activity) and anestrum (absence of overt estrous signs) are major sources of economic loss to buffalo breeders. Studies on the epidemiology of these two problems are highly recommended to achieve successful control. Review of the available literature on controlled studies in dairy buffaloes revealed that first ovulation as detected by rectal palpation and progesterone analysis occurred between 28-71 and 24-55 days, respectively, after calving. Postpartum estrus in the same studies occurred between 44 and 87 days. Reports concerned with data compiled from breeding records of research stations, breeding farms and small holders where estrus is a subjective measure, gave much longer periods. Also data from Egypt, India and Pakistan indicate that only 34-49% of buffaloes showed estrus during the first 90 days after calving and 31-42% remained anestrus for more than 150 days. In swamp buffaloes both postpartum ovulation and estrus are more delayed than in dairy buffaloes. The role of suckling, nutrition, body condition score at calving, milk yield, parity, season of calving and other minor factors were discussed. First postpartum ovulation is frequently followed by one or more short estrous cycles (<18 days). Long anovulatory and anestrous periods due to prolonged inter-luteal phase were reported to occur after short cycles. Also long anestrous periods due to cessation of cyclic activity (true anestrus) for 3 or more weeks and prolonged luteal activity for 28 days or more were described to occur in about 25 and 8-11% of the buffaloes, respectively, after the first or second ovulation. These cycle irregularities certainly impose difficulties on estrus detection programs in postpartum buffaloes. Four main forms of anestrus i.e. true anestrus (inactive ovaries and small and medium sized anovulatory follicles), subestrus, prolonged luteal activity and ovarian cysts in addition to pregnancy are reviewed in this article. Differentiation between true anestrus and subestrus is particularly important in buffaloes because of their weak estrous signs. However, the accuracy of a single rectal palpation of the ovaries is limited with an overestimation of the frequency of true anestrus due to misdiagnosis of the corpus luteum. The possible causes are discussed.     

Factors affecting postpartum ovarian activity in crossbred primiparous tropical heifers

The relationship between postpartum ovarian activity and a total of 9 variables was studied in a dry tropical environment. Primiparous cows (n=61) that had shown no peripartum abnormalities, and were not suckled but milked twice daily, were used in the study. Independent variables included crossbreeding, sex of the calf, season, body condition, weight of cow at calving, age of dam at calving, uterine involution, calf weight and accumulated milk yield. Diet was a controlled variable. Dependent variables were first estrus postpartum and/or first milk progesterone elevation prior to first estrus. A bull fitted with a chin ball marker was used to detect first estrus postpartum, while ovarian structures were palpated per rectum once a week. Progesterone was measured by RIA in milk samples collected twice weekly. First postpartum estrus was detected at 56 +/- 32 days postpartum, a first milk progesterone elevation was observed in 50.8% of cows at 42 +/- 27 days. Cows calving in the dry season had longer intervals and those who calved males had shorter postpartum intervals. Accumulated milk yield affected both intervals significatly (p < 0.01). Weight, age and uterine involution were asociated with first milk progesterone elevation, while crossbreeding, weight at calving and weight postpartum change were associated with the dependent variables.     

Effects of abnormal ovarian cycles during pre-service period postpartum on subsequent reproductive performance of high-producing Holstein cows

The primary objective of this study was to investigate the effects of abnormal ovarian cycles during the pre-service postpartum period on subsequent reproductive performance of high-producing Holstein cows. The study was conducted in a commercial dairy farm with approximately 150 lactating cows, in a subtropical region of Japan. Animals were kept in free-stall barn, and fed a total mixed ration. Cows that calved from June 2001 to July 2002 were included in the study. Milk samples were collected twice weekly from 2 to 11 weeks postpartum, and progesterone concentrations in skim milk were determined by ELISA. After a voluntary waiting period of 40 days, cows detected in estrus were bred by artificial insemination (AI). Pregnancy was confirmed by palpation per rectum 40-70 days after AI. Out of a total of 91 cases, 39 (42.9%) had normal ovarian cycles (ovulation within 45 days after calving, followed by normal ovarian cycles), 32 (35.2%) had prolonged luteal phase (i.e. luteal activity for >20 days), and 12 (13.2%) had anovulation or delayed first ovulation (i.e. first ovulation did not occur until >45 days after calving). The remaining (8.8%) had other types of abnormalities. When compared with cows with a normal ovarian cycle, prolonged luteal phase cows had a lower 100 days AI submission rate, conception rate and pregnancy rate (84.2% versus 56.3%; P<0.05, 50% versus 16.7%; P<0.05 and 42.1% versus 9.4%; P<0.01, respectively), and longer intervals to first AI and to conception ( 67+/-6 days versus 98+/-7 days and 95+/-9 days versus 136+/-11 days; P<0.01 for each). Similarly, when compared with cows with normal ovarian cycles, those with anovulation had lower 100 days conception rate and pregnancy rate (50% versus 0%; P<0.05 and 42.1% versus 0%; P<0.01, respectively), and longer intervals to first AI and to conception ( 67+/-6 days versus 93+/-12 days; P<0.05 and 95+/-9 days versus 155+/-14 days; P<0.01, respectively). Survival analysis of the data for calving to conception interval showed that cows with prolonged luteal phase or anovulation were getting pregnant at a slower rate, and took longer to get pregnant than the cows with normal resumption of ovarian cyclicity postpartum. In conclusion, abnormal ovarian cycles during the pre-service period postpartum adversely affected reproductive performance, including AI submission rate, pregnancy rate, interval to first AI, and calving to conception interval in high-producing Holstein cows.     

Postpartum ovarian follicular dynamics in primiparous and pluriparous Mediterranean Italian buffaloes (Bubalus bubalis)

The objective of this study was to monitor ovarian function in postpartum primiparous and pluriparous Mediterranean Italian buffaloes (Bubalus bubalis) during months of increasing daylength. Ovarian ultrasound monitoring was carried out for a total of 60 days from calving in 10 primiparous and 10 pluriparous buffaloes. Progesterone was determined from calving until a week after first postpartum ovulation. The study was undertaken during months of increasing day length. Time required for complete postpartum uterine involution was 31 +/- 1.0 and 33 +/- 1.3 days in primiparous and pluriparous buffaloes respectively (P = 0.1). The first postpartum ovulation was recorded on 4 primiparous and 8 pluriparous buffaloes (P = 0.16). Time for first postpartum ovulation to occur was 25.5 +/- 6.9 and 15.5 +/- 1.3 days in primiparous and pluriparous buffaloes, respectively (P = 0.07). Overall, 8 of the 12 first postpartum ovulations (66.6%) occurred in the ovary contra-lateral to the one bearing the gravidic CL, one out of 4 in primiparous and 3 out of 8 in pluriparous buffaloes (P = 1.0). Following a first postpartum ovulation, 3 primiparous and 4 pluriparous buffaloes displayed a complete wave of follicular development leading to a new ovulation. Ovulation following parturition was not recorded in 6 primiparous and two pluriparous buffaloes for the 60 days of ultrasound monitoring. Growth rate (mm/d) and largest size (mm) of first postpartum ovulating follicle was 0.95 +/- 0.18 and 1.07 +/- 0.07 (P = 0.4), and 13.5 +/- 0.8 and 14.1 +/- 0.4 (P = 0.4) in primiparous and pluriparous buffaloes, respectively. Following calving, the total number of available antral follicles (> or =2 mm) declined gradually towards the end of the study period. Follicles greater or equal to 3 mm in diameter on the contrary showed a prominent increase in the first 2 weeks from calving. The number of follicles greater or equal to 3 mm in diameter was significantly higher in the ovary contra-lateral to the one bearing the gravidic CL. A balance in the number of such follicles was reached toward the end of the first month. In conclusion, although some follicular activity was recorded in the ovaries of all buffaloes, true postpartum resumption of cyclicity in the months of increasing daylight hours was delayed in the majority of animals.     

Impact of pre-ovulatory follicle diameter on plasma estradiol, subsequent luteal profiles and conception rate in buffalo (Bubalus bubalis)

The present study was designed to investigate the impact of pre-ovulatory follicle (POF) diameter on the day of estrus on plasma estradiol concentration, subsequent luteal profile (corpus luteum, CL, diameter and plasma progesterone concentration) and conception rate in buffaloes. Twenty-eight buffaloes were synchronized with synthetic analogue of prostaglandin F(2α) (PGF(2α)) administered 11 days apart. Transrectal ultrasonography and jugular vein blood sampling was carried out on the day of estrus and on days 0 (day of ovulation), 5, 12, 16 and 21 post-ovulation. Out of 28 buffaloes, 11 (39.3%) were diagnosed pregnant on day 40 post-ovulation. Retrospective analysis revealed that the buffaloes getting pregnant had larger (p<0.05) POF diameter. In fact, all the buffaloes (n=5/5) having POF diameter between >14 and 16 mm conceived, whereas, conception rate in buffaloes with POF diameter between >12 and ≤14 mm (n=6/17) or <12 mm (n=0/6) was 35.3% and 0.0%, respectively. A positive correlation (r=0.57, p<0.05) was observed between POF diameter and plasma estradiol concentration at estrus. On day 5 post-ovulation, luteal profile was positively correlated (CL: r=0.34, p<0.05; plasma progesterone concentration: r=0.27, p>0.05) with POF diameter. Further, on the same day, plasma progesterone concentration was positively correlated (r=0.47, p<0.05) with CL diameter, however, this correlation was absent (r=0.05, p>0.05) during the subsequent luteal phase. Nevertheless, the post-ovulation luteal profile of pregnant buffaloes was higher (p<0.05) compared to non-pregnant counterparts. In conclusion, the diameter of POF in buffaloes has positive impact on plasma estradiol concentration at estrus, post-ovulation luteal profile and conception rate. The diameter of CL can be used as an indicator of luteal function at early but not at mid or late luteal phase of estrus cycle in buffaloes.     

Resumption of postpartum ovarian cyclicity in high-producing Holstein cows

The objective of this study was to investigate the resumption of ovarian cyclicity postpartum in high-producing dairy cows in commercial dairy farms under subtropical conditions. The cows were kept in a free-stall or tie-stall barn. Milk samples were collected from cows twice weekly, and progesterone in the skim milk was assayed by double-antibody ELISA. Cows were examined rectally and vaginoscopically at 2-week intervals after calving. Body condition score (BCS) and body weights were taken before and after calving. A cow was considered to have resumed ovarian cyclicity on the day of ovulation if followed by regular ovarian cycles. Thirty seven percent (n=20/54) of the cows had normal resumption of ovarian cyclicity (resumption within 45 days after calving), and 63% (n=34/54) had delayed resumption (resumption did not occur until >45 days after calving). Delayed resumption Type I (one or more ovarian cycles with luteal phase >20 days, i.e. prolonged luteal phase; 31.5%) and delayed resumption Type II (first ovulation did not occur until > or =45 days after calving, i.e. delayed first ovulation; 24.1%) were the most common types of delayed resumptions. Almost half (46.3%) of the cows did not resume their ovarian cyclicity until >65 days postpartum. Cows with delayed resumption Type I had a higher incidence of abnormal cervico-vaginal discharge (64.7%) and incomplete uterine involution (94.1%) compared to cows with normal resumption (P<0.01). The BCS of cows with delayed resumption Type II were lower than those of normal resumption cows at 5 weeks and later in the postpartum period (P<0.05). Approximately two-thirds of high-producing cows had delayed resumption of ovarian cyclicity postpartum. Prolonged luteal phase and delayed first ovulation were two important ovarian dysfunctions that delayed postpartum resumption of cyclicity in high-producing dairy cows.     

Effect of subclinical uterine infection on cervical and uterine involution, estrous activity and fertility in postpartum buffaloes

Nili-Ravi buffaloes (n=29) that calved normally between August and November and did not develop any clinical reproductive disorder after calving were studied for the incidence of sub-clinical bacterial infection of the uterus and its effects on postpartum reproductive efficiency. The incidence of subclinical uterine infection was 24% (7/29). Involution of the cervix and uterus was slower (P < 0.01) in the infected group than in the normal group (45.6 vs 31.1 days and 46.3 vs 35.8 days), respectively. The mean diameters of cervix and gravid horn on Day 12 post partum and on completion of involution did not differ between buffaloes of the two groups. However, the rate of involution of the cervix and the gravid horn was lower in buffaloes of the infected group (2.2 vs. 2.7 mm/day and 2.6 vs. 3.2 mm/day). The mean interval to first post partum ovulation was similar in buffaloes in the infected (35.5 days) and the normal group (33.8 days). The life span of corpus luteum formed after first ovulation was shorter (11 days) in buffaloes of both groups than that of a normal estrous cycle (15 to 17 days). The incidence of silent ovulation was apparently higher in buffaloes of the infected group (83 vs. 60%) but the difference was not significant. For the first four months after calving, the mean interval to first postpartum estrus was longer in buffaloes of the infected group (73.0 vs. 47.7 days; P < 0.01). Similarly, the average service period was longer in buffaloes of the infected group (91.0 vs. 64.8 days; P < 0.05). The overall pregnancy rate for the first four months after calving did not differ between buffaloes of the two groups. We conclude that subclinical bacterial infection of the postpartum uterus delays the cervical and uterine involution which can, in turn, delay the occurrence of first postpartum estrus and prolong the service period in buffaloes.     

Effect of restricted suckling on ovarian activity and uterine involution in Brahman cows

Seventy-six Brahman cows and first-calf heifers ranging in age from three to five or more years were used to determine the effects of restricted suckling on postpartum ovarian activity and uterine involution. At 30 days postcalving, cows were randomly assigned to one of two groups: 1)normal suckling (34 cows) and 2)twice-daily suckling (42 cows). The cows were examined by rectal palpation weekly from parturition until the onset of the breeding season. The average interval from parturition to the presence of the first follicle larger than 10 mm (PPFI) was 36.0 +/- 1.0 days, and twice-daily suckling decreased PPFI length 8.1 days (P < 0.01); likewise, first- and second-calf heifers tended to have longer PPFI length (P < 0.05) than cows with three or more calvings. The average interval from parturition to first corpus luteum (PPCLI) was 59.0 +/- 2.0 days. PPCLI was affected by the age (P < 0.05) and weight of the cow at 30 days postpartum (P < 0.10). The average interval from parturition to first estrus (PPEI) was 68.0 +/- 5.0 days. PPEI was affected by suckling (P < 0.10) and month of parturition (P < 0.05). The average interval from parturition to uterine involution was 33.0 +/- 1.0 days. Uterine involution was influenced by month of calving (P < 0.01) and age of the cow (P < 0.05).     

Effect of melatonin on postpartum anestrus in beef cows

The effect of melatonin treatment on intervals from calving to first postpartum estrus and ovulation was determined in Shorthorn cows which calved May 8 to June 14. Melatonin (500 mg in beef tallow) was injected subcutaneously (s.c.) into 20 cows on June 15 (4 to 38 d postpartum). Ovulation was determined from progesterone concentrations in jugular venous blood collected weekly from June to August. Mean intervals to first estrus and first ovulation were significantly longer in primiparous than in multiparous cows (85 +/- 4 vs 55 +/- 3 d and 83 +/- 4 vs 52 +/-3 d). Melatonin treatment caused a significant increase in the intervals to first postpartum estrus (68 +/- 4 vs 58 +/- 5d) and ovulation (68 +/- 4 vs 55 +/- 5 d). Mean plasma melatonin concentrations during the daytime were significantly higher in treated than in control cows one and two weeks after melatonin injection and were within the lower range of nighttime values reported previously for cows. Thus melatonin treatment raised daytime plasma concentrations of melatonin and delayed the onset of estrus and ovulation. These results support the possibility of a role of photoperiod through melatonin secretion in the onset of postpartum ovarian activity in cattle.     

Relationships between body condition score, body weight, and some nutritional parameters in plasma and resumption of ovarian cyclicity postpartum during pre-service period in high-producing dairy cows in a subtropical region in Japan

The objective of this study was to investigate the relationships among body condition score (BCS), body weight and plasma metabolite concentrations, and resumption of ovarian cycles postpartum in high-producing dairy cows in a subtropical region in Japan. The study was conducted between May 2001 and January 2003 in a commercial dairy farm in Hiroshima. Cows were kept in free-stall barns with sawdust and wood shavings for bedding, and fed a total mixed ration consisting of alfalfa, timothy and oat hay, corn, tofu ground-wet, beet pulp, cottonseed and soybean. Milk samples were collected twice weekly from 2 to 11 weeks postpartum, and progesterone concentrations in skim milk were determined by ELISA. At 8 and 2 weeks before calving and 3, 5, 7, 9, and 11 weeks after calving, both BCS and body weights were determined and blood samples were collected to determine plasma concentrations of total cholesterol (T-cholesterol), non-esterified fatty acids (NEFA), total protein, and urea nitrogen. The average 305 days milk yield was 10,422 kg. Out of 110 cows, 44.5% had normal resumption (ovulation occurred < or =45 days after calving, followed by regular ovarian cycles), 33.6% had a prolonged luteal phase (luteal activity >20 days), 12.7% had delayed first ovulation (no ovulation until < or =45 days after calving), 4.6% had a short luteal phase (luteal activity <10 days, except in the first cycle), and the remaining 4.6% had cessation of cyclicity (no luteal activity > or =14 days between cycles). The BCS of cows with delayed first ovulation were lower than the BCS of cows with normal resumption and prolonged luteal phase at 5 weeks (2.9+/-0.1 versus 3.1+/-0.1 and 3.2+/-0.1; P<0.05), 7 weeks (2.8+/-0.1 versus 3.1+/-0.1 and 3.2+/-0.1; P<0.01), 9 weeks (2.7+/-0.1 versus 3.0+/-0.1 and 3.2+/-0.1; P<0.01) and 11 weeks (2.6+/-0.1 versus 3.0+/-0.1 and 3.2+/-0.1; P<0.01) after calving. None of the plasma parameters differed (P>0.05) among different groups of cows. Cows loosing > or =1 unit BCS after calving had a prolonged interval to commencement of luteal activity, and were at greater risk of having delayed first ovulation. Poor postpartum nutritional status was associated with delayed first ovulation postpartum. Regular monitoring of BCS before and after calving would be useful in nutritional management, and help in preventing delayed first ovulation in high-producing dairy cows.     

Milk progesterone profiles in various reproductive states in dairy buffaloes under field conditions

Fifty-one dairy buffaloes in the last two months of gestation were selected at seven private peri-urban farms in the Peshawar district. Observations were recorded in buffaloes during normal (NBS, August to January) and low breeding seasons (LBS, February to July). After parturition, rectal examination of reproductive organs was carried out. Estrus detection was made through visual observation and the use of intact bull. Postpartum ovulation was confirmed by ovarian palpation per rectum and milk progesterone levels (MPL), determined through radio-immunoassay. MPL was higher (p < 0.01) at various intervals in NBS calves (1.97 +/- 0.30 ng/ml) as compared to LBS calves (0.68 +/- 0.08 ng/ml). During LBS, MPL remained < 0.30 ng/ml up to the third fortnight and started rising later, reaching a peak of 1.27 ng/ml during the sixth fortnight. During NBS, there was a sharp rise in MPL during the second fortnight, reaching 3.64 ng/ml during the sixth fortnight. MPL was significantly different on different experimental farms (p < 0.01). MPL reached the lowest levels on the day of estrus (0.10 ng/ml), reached it's peak on day 7 and started declining on day 17 of estrus. MPL showed two postpartum elevations. In true anestrus buffaloes, MPL remained consistently low. However, in the anestrus period, silent ovulations were also noted, as reflected by increasing MPL without estrus signs. In pregnant buffaloes, MPL remained > 1 ng/ml. Results of the study showed that the low postpartum reproductive performance in dairy buffaloes during LBS was primarily due to inadequate functioning of the corpus luteum in secreting optimum concentrations of progesterone. The higher incidence of silent estrus during LBS indicated improved management for the detection of estrus.     

Luteal competency during the resumption of ovarian cyclicity in postpartum Brahman cows

Twenty pluriparous, spring-calving Brahman cows were used to determine luteal competency, as measured by serum progesterone concentrations, during the first and the second postpartum estrous cycles. Prior to and after calving, all cows were maintained in good body condition on Coastal bermudagrass pasture (IFN 1-00-703). The calves were allowed to suckle ad libitum, and sterile marker bulls were maintained with the cow herd as an aid in estrus detection throughout the trial. Cow weight and body condition score were recorded within 24 hours after calving and again at the first behavioral estrus observed. From day 1 through day 14 (day 0 = estrus) of both the first and the second postpartum estrous cycles, blood samples were collected from each cow, processed to yield serum and analyzed by radioimmunoassay for progesterone concentrations. There was a higher incidence of abnormal estrous cycles following the first postpartum estrus (35%) than following the second (5%) postpartum estrus (P<0.05). The abnormal first estrous cycles were characterized by either a short luteal phase (four cows) or by standing estrus behavior without luteal tissue formation (three cows). When serum progesterone concentrations were compared for all cows during the first estrous cycle with those during the second estrous cycle, there was less progesterone released during the cycle (P<0.05) and lower peak progesterone concentrations (P<0.10) during the first estrous cycle. However, if the abnormal cows were excluded from the analyses, there was no difference (P>0.10) in either progesterone concentrations through the 14 days measured or in peak progesterone concentrations between the first and the second postpartum estrous cycles. It can be concluded from this study that the higher incidence of abnormal luteal function following the first postpartum estrus may contribute to the decreased conception rates observed when cows are bred at their first postpartum estrus.     

Resumption of ovarian function in autumn lambing Dorset, Rambouillet and Finnish Landrace ewes

The establishment of ovarian activity during lactation was studied in the postpartum period of Rambouillet, Dorset and Finnish Landrace ewes following lambing during the month of October (1981). The mean postpartum intervals to first ovulation and first estrus were 22.7 and 53.0 for Rambouillets, 25.2 and 51.0 for Dorsets, and 22.5 and 49.7 days for Finnish Landrace ewes. Estrus was not associated with the first ovulation postpartum in any breed. The number of silent ovulations prior to the first estrus was highest in the Rambouillet and lowest in Finnish Landrace breeds. Of the 18 ewes in the project, 14 had normal luteal phase lengths, 1 had a possible short luteal phase and 3 had prolonged luteal phases following the first ovulation postpartum. The first service conception rate of all ewes bred was 82% (14 17 ) at an average of 52 days postpartum. The lambing rate following the autumn breeding was higher (2.14 +/- 0.14) than the lambing rate which followed the previous spring breeding (1.28 +/- 0.11).     

Interaction of calf suckling, use of oxytocin and milk yield with reproductive performance of dairy buffaloes

Calf suckling and oxytocin injections are commonly used for pre-milking stimulus in dairy buffaloes under field conditions. A study was conducted to investigate effect of these treatments on reproductive performance. Fifty one Nili-Ravi buffaloes were monitored from parturition up to 150 days postpartum through rectal examination. Data on milk yield, body condition score (BCS) and reproductive parameters were recorded weekly. Postpartum ovulation interval (POI) was determined by presence of an ovulation depression or a very soft corpus luteum haemorrhagicum and was confirmed through milk progesterone levels (MPL). Suckling was used to stimulate milk let down, and where the calf had died, injection of oxytocin was resorted to. Milk samples were analyzed for MPL using radioimmunoassay (RIA) and fat; and milk yield was converted to 4% fat corrected milk (FCM). The mean postpartum uterine involution length (PUI) was 34.30 ± 1.33 days. Mean POI was 59.37 ± 4.76 days and mean postpartum estrus interval (PEI) was 69.03 ± 6.03 days. Suckling period averaged 26.40 ± 5.57 days and correlated with POI (r = 0.19, P < 0.01) and PEI (r = 0.23, P < 0.01). POI was shortest in buffaloes suckled for one month (P < 0.05). Oxytocin was used with a mean dosage of 7.50 IU, delaying placental expulsion time (PET) and POI but shortening PEI. BCS shortened PET, POI and PEI (P < 0.01). Mean FCM was 14.50 ± 0.20, ranging from 2 to 35 kg/d; and was higher in estrus group; correlating positively with POI (r = 0.31, P < 0.01). MPL were 1.37 ± 0.17 ng/ml and increased after ovulation, remaining greater than 1.5 ng/ml from Day 4 to 14 of the estrus cycle, followed by a rapid decline up to next estrus. BCS in buffaloes resuming oestrus was constantly higher than those failing to resume ovarian cyclicity. Live weight, prepartum was 510.0 ± 5.9 kg with a loss of 3.7 ± 2.12 kg, 30 days postpartum. The present study suggests a lower reproductive efficiency of dairy buffaloes under the peri-urban farming system reflected by ovarian cyclicity in 68.63% buffaloes within 150 days postpartum and silent estrus in 51.5% of the cases. Increasing suckling duration and use of oxytocin delayed POI, however, POI was shortest in buffaloes suckled for one month. The high yielding buffaloes also manifested better reproductive cyclicity; while moderate yielder showed shorter ovulation intervals and higher conception rate.     

Postpartal ovarian activity of healthy cows and those affected by subclinical metabolic disorders

The postpartal ovarian activity was studied in healthy cows and in those affected by subclinical fatty liver disease and subclinical primary ketosis. Twenty-six dairy cows, 4–7 years old, with not less than 5000 l milk yield in the preceding lactation, were monitored for the following blood parameters: aspartate-amino-transferase (AST)/glutamicoxalacetic transaminase (GOT), albumin, total protein, total lipid, cholesterol, non-esterified fatty acid (NEFA) and triglyceride levels, glucose and ketones. The ratios albumin : total protein and NEFA : triglyceride were also calculated. Blood samples were collected once a week between days 255 and 260 of gestation and days 1–15 postpartum, and subsequently on the 30th, 45th and 60th days postpartum. Based on the biochemical parameters, the cows were assigned in retrospect to three groups: (1) healthy (n = 5), (2) subclinical fatty liver disease (n = 6), and (3) subclinical primary ketosis (n = 10). The postpartal ovarian activity was assessed by rectal palpation and by milk progesterone levels, determined by radioimmunoassay in samples collected 2–3 times weekly between days 5 and 70 postpartum.As early as 10–18 days postpartum, ovarian activity was evident in healthy cows. This was confirmed by the progesterone profiles indicating three regular ovarian cycles with normal hormone levels within 70 days postpartum. All five healthy cows were detected in estrus and only one failed to conceive after insemination.The six cows with subclinical fatty liver disease had no regular cycles and only a few small follicles were palpable on their ovaries. The milk progesterone fluctuated around the basal level (? 1.6 nmol/l). The first Graafian follicles appeared as late as days 30–35 postpartum and the luteal function commenced only between days 38 and 60, as indicated by palpation of corpora lutea and a concomitant rise in milk progesterone. The progesterone peaks were at the lower physiological limits characteristic of luteal function.The ovarian activity of the ten cows with subclinical primary ketosis was intermediate between that of healthy and fatty liver cows. The first follicles and corpora lutea were somewhat delayed, and the progesterone levels fluctuated considerably during the luteal phase. One cow in this group resumed ovarian inactivity during the 70-day postpartal observation period.     

Follicular dynamics during postpartum anestrus and the first estrous cycle in suckled or non-suckled Brahman (Bos indicus) cows

Brahman (Bos indicus) cows, were selected at 28+/-10 days after calving and analyzed by real time rectal ultrasonography three times a week, in order to evaluate and compare follicular and corpus luteum development during postpartum (PP) anestrus and the first PP estrous cycle under sylvopastoril conditions. Suckling (S, n=11) or non-suckling (NS, n=5) cows were evaluated in a zone of tropical dry forest (450m of altitude, mean temperature=27 degrees C, annual rainfall=1000mm). Estrous detection was performed twice daily by direct observation. Progesterone was quantified using RIA. From 28+/-10 days postcalving to resumption of estrous cycles, there were no differences (P>0.05) between NS and S cows for diameter of the dominant or first subordinate follicle, follicular growth rate, or interdominance interval. Silent ovulation, corpus luteum formation and subsequent progesterone concentrations ranging from 0.3 to 9. 7ng/ml, were found in both groups. The first calving to ovulation and calving to standing estrus intervals were shorter (P<0.01) in NS (34.8+/-5.81 and 41.2+/-9.03 days) than in S (65+/-4.82 and 81+/-6. 21 days) cows. Follicular development and progesterone concentrations during the first PP estrous cycle did not differ (P>0. 05) between NS and S cows. These results suggest that Brahman cows could have an early PP resumption of follicular recruitment if fed under sylvopastoril system conditions. However, non-suckled cows did have an earlier standing estrus and ovulation than did suckled cows.     

The postpartum buffalo: I. Endocrinological changes and uterine involution

To maintain a calving interval of 13-14 months in buffaloes, successful breeding must take place within 85-115 days after calving. Disturbances during this period due to delay of uterine involution or resumption of estrous activity are likely to prolong the calving interval and reduce the lifetime reproductive and productive efficiency. In this article literature on endocrinological changes in the peripartum period and on factors affecting uterine involution are reviewed. The available information indicated that although the availability of releasable FSH does not appear to be a limiting factor for resumption of postpartum cyclicity a substantial increase of releasable LH and replenishment of pituitary stores occurred around Day 20 in dairy and Day 30 in swamp buffaloes. There is evidence that follicular activity is resumed early (15-30 days) in the postpartum period. However, the factors which initiate release of appropriate LH pulses, follicular maturation and ovulation in the postpartum buffalo need further studies. The mean interval to complete uterine involution varied widely between 19 and 52 days. Assessment of cervical and uterine horn diameters by rectal palpation alone is not satisfactory to diagnose delayed uterine involution and possible subclinical uterine infection. Vaginal inspection can be included as a fundamental part of postpartum genital examination for diagnosis of such case. Uterine involution, however, does not seem to be a limiting factor for achievement of satisfactory fertility in the postpartum buffalo but the main determinant is resumption of estrous activity.     

Effect of dietary lipid supplementation on progesterone concentration and reproductive performance in suckled beef cows

Using whole cottonseed as a lipid source, silage-based diets that were isocaloric and isonitrogenous yet varied in lipid level were fed to multiparous cows. In Experiment 1, 48 cows (n = 12 per treatment) were allotted to 1 of 4 treatments where diets were formulated to supply 3.9, 4.3, 5.3 and 6.3% of total lipid. In Experiment 2, 66 cows (n = 22 per treatment) were allotted to 1 of 3 treatments where diets were formulated to supply 3.1, 5.5 and 8.3% of total lipid. Length of the first ovarian cycle, length of the first normal estrous cycle, postpartum intervals to onset of ovarian luteal activity and to first estrus were not affected by diet (P>0.10) in either experiment. Mean progesterone (P(4)) concentrations for first normal estrous cycles were not different (P>0.10) in either experiment. Anestrous periods were divided into 3 phases for analyses: Phase I) parturition to onset of ovarian luteal activity, Phase II) first ovarian luteal activity and Phase III) first normal estrous cycle. No differences were observed in P(4) concentrations during any phase of the postpartum period. In conclusion, isocaloric and isonitrogenous diets with increasing levels of lipid had no effect on reproductive performance in suckled beef in these experiments.     

Influence of bull biostimulation, season and parity on resumption of ovarian activity of zebu (Bos indicus) cattle following parturition

A total of 135 postpartum suckled zebu cows were assigned randomly at calving to two treatments: cows exposed to vasectomised bulls (Mature Bull Exposure, MBE) and cows not exposed to bulls (No Bull Exposure, NBE) for a period of 150 days postpartum. This study was conducted to determine the influence of bull biostimulation, season and parity on postpartum reproductive performance of Bos indicus cattle. The trials were conducted in two seasons: cows calving in the dry season and cows calving in the rainy season. Cows with an increase in serum progesterone (P(4)) concentration of >1 ng/ml from the weekly blood samples were used to analyse the number of days from calving to the time of resumption of ovarian activity. The introduction of vasectomised bulls shortened the postpartum anoestrus in cattle following calving. Mean interval from calving to resumption of ovarian activity for the MBE cows was 71.7 days, which was significantly earlier following calving than the NBE cows with a duration of 77.8 days. By 60 to 80 days postpartum, the proportion of cows at resumption of postpartum activity for MBE cows was greater than for the NBE cows.Mean interval from calving to resumption of ovarian activity for cows that calved in the dry season was 71.3 days, which was significantly earlier than for cows that calved in the rainy season (78.6 days). At 60 days postpartum, the proportion of cows at resumption of postpartum ovarin activity for cows that calved in the dry season was greater than the cows that calved in the rainy season. Mean interval from parturition to resumption of ovarian activity for cows with three to five calvings was 65.1 days, which was significantly earlier than the value of 71. 2 days for cows with one to two calvings. By 60 to 80 days postpartum, the proportion of cows at onset of ovarian activity for cows with three to five calvings was greater than those cows with one to two calvings. Cows that calved in the dry season completed uterine involution by 24.4 days, which was significantly shorter than the duration of 26.5 days for cows that calved in the rainy season. Cows with three to five calvings completed uterine involution earlier than those with one to two calvings. It is concluded that bull-cow biostimulation influences reproductive activity in the cow possibly through olfactory cues (pheromones).