Resumption Of Postpartum Ovarian Activity Research Articles

Postpartum longissimus dorsi muscle loss, but not back fat, is associated with resumption of postpartum ovarian activity in dairy cattle

The objectives of this observational cohort study were to assess the effect of body condition score change, back fat depth change, and muscle diameter change on the time to commencement of luteal activity and first estrus in commercial pedigree Holstein cows. One hundred and 40 of 200 commercial pedigree Holstein cows were enrolled in one dairy herd in Somerset, United Kingdom, over 52 weeks in 2021-22. The herd used 4 automatic milking machines with in-line progesterone measurement capability to determine commencement of luteal activity and time to first estrus. Cows were followed until at least 60 d postpartum and milk progesterone measured daily starting from 10 DIM. Body condition scoring and ultrasound measurements of back fat depth and Longissimus dorsi muscle diameter were performed on cows twice: within 7 d of both calving and 60 DIM. Other explanatory variables assessed included parity, 60-d and 305-d milk yield, and subclinical ketosis (β-hydroxybutryate (βHB) ≥ 1.2mmol/L). Occurrence of clinical disease <60 DIM was forced into all models as a binary variable. Data were analyzed using multivariable cox proportionate survival analyses. Muscle loss was associated with commencement of luteal activity and time to first estrus. A reduction in muscle diameter by 1.5 to 5 mm was associated with the shortest time to the start of luteal activity and first estrus. A reduction in muscle diameter >8 mm was associated with the longest times to luteal activity and first estrus. In addition to being affected by muscle loss, commencement of luteal activity was delayed by subclinical ketosis, clinical disease, and failure to gain body condition to 60 DIM. Cows that had a BCS loss of 0.25 or more between calving and 60 DIM were at least 52 ± 22% less likely to have commenced luteal activity compared with those that gained BCS. Interestingly, cows that had no change in body condition score commenced luteal activity later than those that gained body condition score. Muscle loss was associated with time to first estrus irrespective of clinical disease status. Cows that lost > 8 mm of muscle diameter showed estrus behavior later than cows that lost 1.5 to 5 mm. In conclusion, our findings indicate that extensive muscle loss postpartum was associated with a delayed start to luteal activity and first estrus irrespective of body condition change, clinical disease, and subclinical ketosis. Marginal muscle loss and a gain in body condition, however, were associated with an earlier start to luteal activity and first estrus.

Association of thyroid hormone profile with resumption of postpartum ovarian activity in dairy cows

The objective of this study was to assess the association between thyroid hormone profile and resumption of postpartum ovulations in cattle. Lactating Holstein cows (n=40, milk yield 38.51±1.23 kg/d) were selected and based on the ultrasound results, blood estradiol and progesterone analysis, were divided into two groups. The cows were classified into anovulatory (AO) group if the first ovulation did not occur until 45 days after calving (n=16) and ovulatory group (O) if the first ovulation occurred 45 days or less after calving (n=24). Blood samples were collected from the cows weekly from day 21 to 48 postpartum to evaluate thyroid hormone levels and blood parameters. Results showed that milk yield and glucose concentrations did not differ between the groups. Serum estradiol and progesterone concentrations in ovulatory cows were significantly higher than those in AO cows. Cows in O group had better condition with respect to days to first service (DFS), open days (OD), days to first ovulation (DFO) and conception rate than cows in AO group. Thyroid hormone analysis show that T4 concentration and T4:T3 ratio in the AO group were significantly higher than those in O group (P=0.001), while there were no statistically significant differences between groups for T3 concentrations. Also, T3 and T4 concentrations and T4:T3 ratio in both groups were not affected by time (P=0.17) and time×group interaction (P=0.25). In addition, no significant difference was found in the non-esterified fatty acids (NEFA) concentration between the two groups. Unlike NEFA, beta-hydroxybutyric acid (BHBA) levels in AO group were significantly higher than those in O group (P=0.01). In conclusion, cows with different ovarian activity postpartum had different thyroid hormone profile. Increased T4 concentration and T4:T3 ratio were associated with delay in ovulation and resulted in greater day to first service and open days and followed by lower conception rate.

Body status and blood metabolites profiles during resumption of postpartum ovarian activity in yak (Poephagus grunniens).

We examined the changes in body weight (BW), back-fat thickness (BFT) and blood metabolites in relation to postpartum (PP) ovarian activity status in twenty female yaks raised under semi-intensive system. BFT and ovarian activities, like follicle development, ovulation (OV) and corpus luteum (CL) development, were monitored from 4 to 15weeks (wk) PP using ultrasonography. Resumption of ovarian activity was confirmed with ovulation of dominant follicle (DF) and subsequent CL development, and >1ng/ml progesterone concentration in blood plasma sample after 1week of ovulation. Yaks were further classified as cyclic (with CL), acyclic (without CL), and cystic (with >25mm follicular cyst; FC). Within 20weeks PP, 60% yaks resumed cyclic ovarian activity, while 25% failed to initiate cycling activity, and 15% developed follicular cysts. In all categories of yak, BW gradually decreased (p<.05) till nadir; however, nadir reached earlier (p<.05) in acyclic yaks. BFT differed (p<.05) among the yak groups, but it tended to be higher in cyclic yaks as compared to acyclic and cystic. No difference (p>.05) in non-esterified fatty acids (NEFA) values was found among the different categories of yaks, whereas, beta-hydroxy butyrate (BHB) levels were higher in cystic animals as compared to acyclic and cyclic. Blood glucose levels decreased in all yaks during initial 2weeks after calving. Our findings suggest that yaks with low BW, BFT and glucose levels, and higher BHB values were at risk of delayed resumption of ovarian activity and concomitant development of follicular cysts.

POSTPARTUM CONCENTRATIONS OF ESTRADIOL AND PROGESTERONE IN THREE GENOTYPE OF SHEEP FED VARYING LEVELS OF PROTEIN

The study aims to evaluate the effects of feeding different protein levels on the resumption of postpartum ovarian activity by measuring serum estradiol (E2) and progesterone (P4) concentrations bi-weekly starting one week postpartum in three genotypes of sheep (Yankasa, Uda and Balami). Eighteen (18) multiparous sheep with aged range of 2.5 – 3 years old consisting of six (6) each of Yankasa, Uda and Balami breeds were divided into three groups and reared on different protein concentrations. The protein concentrations were 15.2% (high), 9.5% (medium) and 6.5% (low). Results showed a gradual increase of estradiol in both Yankasa and Uda breeds fed low protein diet from 100 – 3000 concentration. However, Uda breed had the highest value of estradiol when both medium and high protein diets were fed to the three genotypes of sheep. Nevertheless, Yankasa sheep had more consistent values of progesterone when fed low protein diet compared to Balami and Uda. Also Uda breed recorded the highest progesterone values in both medium and high protein diets among the three genotypes followed by Yankasa sheep. All the three genotypes returned to estrous earlier on high protein concentration followed by those on medium protein level. It is concluded that increase protein concentration hastened resumption of ovarian cyclicity and thereby leading to increase fertility in sheep

Metabolic Changes in the Blood of Dromedary Camel at Early Post-partum

Postpartum resumption of ovarian activity under environmental stressors is highly important for determining subsequent fertility in camel. The current study aimed to investigate the relationship of relevant biochemical and hormonal parameters in the blood serum with regard to ovarian resumption of dromedary camel at early post-partum. Blood samples were collected from female dromedary camel weekly during the postpartum period for 9 successive weeks. Serum and plasma samples were assayed for the following biochemical and hormonal constituents, glucose, cholesterol (CH), triglycerides (TG), total protein (TP), urea, insulin-like growth factor-1 (IGF-1), non-esterified fatty acids (NEFA), lactate dehydrogenase (LDH), cortisol and triiodothyronine (T3). Glucose concentrations ranged between 92.6 and 96.2 mg/dL for the first 6 weeks postpartum, and increased to 106.8 mg/dL at week 7 postpartum (P &amp;lt; 0.01). The concentrations of CH followed almost the same manner during the first 7 weeks (ranged between 27.5 and 30.4 mg/dL) and increased to 38.2 mg/dL at week 8 postpartum (P &amp;lt; 0.01). Likewise, total protein concentrations decreased from 6.86 g/dL week2 to 6.45 g/dL at week 3 (P &amp;lt; 0.01) with no significant changes thereafter. Similarly, triglycerides decreased from 24.5 mg/dL at week 2 to 13.00 mg/dL at week 3 (P &amp;lt; 0.01) with no significant changes up to week 9. The concentrations of NEFA decreased significantly at week 3 postpartum (P &amp;lt; 0.01) and then maintained at low level throughout the study period. Similarly, cortisol and IGF-1 concentrations were the lowest at week 3 postpartum (5.7 &amp;micro;g/dL and 93.7 &amp;micro;g/mL for cortisol and IGF-1, respectively, P &amp;lt; 0.01) and then increased gradually with some little variations of IGF-1. However, the levels of urea followed a characteristic increasing and subsequently decreasing patterns while reached a plateau at weeks 8 and 9 postpartum. Similarly, the concentrations of T3 followed the same pattern and tended to increase at week 9 postpartum. Concentrations of LDH showed a significant decrease at weeks 4 to 6 postpartum and increased thereafter (P &amp;lt; 0.01). Throughout the study period, changes of glucose, cortisol, CH, TP, IGF-1, NEFA and LDH had a clear trend, i.e. decreasing at early postpartum period followed by increasing patterns thereafter. The results of the present study suggest that the typical metabolic patterns that are found in blood serum of dromedary camel at postpartum may be reflected in the follicular fluid and, therefore, may use as an indication of reproductive resumption.

Effects of 3-nitrooxypropanol on rumen fermentation, lactational performance, and resumption of ovarian cyclicity in dairy cows

This study examined the effect of 3-nitrooxypropanol (3-NOP), a substance under investigation, on enteric methane (CH4) emission, rumen fermentation, lactational performance, sensory properties of milk, and the resumption of ovarian cyclicity in early-lactation dairy cows. Fifty-six multi- and primiparous Holstein cows, including 8 that were rumen cannulated, were used in a 15-wk randomized complete block design experiment. Cows were blocked based on parity and previous lactation milk yield (MY) or predicted MY, and within each block were randomly assigned to one of 2 treatments: (1) control (CON), administered no 3-NOP, or (2) 3-NOP applied at 60 mg/kg of feed dry matter (3-NOP). Enteric CH4 emission was measured during experimental wk 2, 6, 9, and 15, using the GreenFeed system. Dry matter intake (DMI) and MY data were collected daily throughout the experiment, and milk composition samples were collected 7 times during the experiment. Milk samples were collected from 14 to 60 (±2) d after calving, 3 d per week, and assayed for progesterone concentration to determine resumption of ovarian activity. Compared with CON, 3-NOP decreased daily CH4 emission by 26%, CH4 yield (CH4 per kg of DMI) by 21%, and CH4 emission intensity [CH4 per kg of MY or energy-corrected milk (ECM)] by 25%. Enteric emission of carbon dioxide was decreased by 5%, and hydrogen emission was increased 48-fold by 3-NOP. Inclusion of 3-NOP decreased concentration of total volatile fatty acids (by 9.3%) and acetate but increased butyrate molar proportion, ethanol, and formate concentrations in ruminal fluid. Dry matter intake was lower for 3-NOP compared with CON, but DMI expressed as a percentage of body weight was not different between treatments. Treatment had no effect on milk and ECM, body weight change, or body condition score. Milk composition and milk fat and protein yields were not affected by treatment, except that concentrations of short-chain fatty acids in milk were increased by 3-NOP. Nutrient digestibility and blood metabolites and hormones were not affected by 3-NOP, except that insulin was decreased by 3-NOP. There was no effect of 3-NOP on postpartum resumption of ovarian activity, including days to first and second luteal phases, length of first and second luteal phases, and interval from first to second luteal phase. Sensory properties of milk from cows fed 3-NOP and cheese made from that milk were not affected by treatment. In this experiment, 3-NOP decreased daily enteric CH4 emission, emission yield, and emission intensity, improved feed efficiency, and did not affect lactational performance or onset of ovarian activity in early-lactation dairy cows.

Effects of parity on productive, reproductive, metabolic and hormonal responses of Holstein cows

The objective of this study was to determine the effects that parity may have on production, reproduction and the metabolic status of Holstein cows managed in a production system based on total mixed ration and pasture. Primiparous (n = 22) and multiparous (n = 24) cows from a dairy farm research station in Uruguay were used in a completely randomized design. Body weight (BW), body condition score (BCS) and backfat thickness (BFT) were recorded weekly from −30 to 70 days postpartum. Milk production was measured daily, and milk composition was determined weekly. Resumption of postpartum ovarian activity and progesterone profiles were measured three times a week based on milk progesterone. Blood was collected to determine the levels of glucose, insulin-like growth factor I (IGF-1), insulin, non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), albumin, total protein and cholesterol. Milk production and components were lower for primiparous cows (p < 0.01) than multiparous cows. Body weights were also lower in primiparous cows than in multiparous cows (p < 0.05); however, BCS and BFT were greater (p < 0.01) in primiparous cows than in multiparous cows. Primiparous cows had greater levels of glucose, insulin and IGF-1 and lower concentrations of NEFA and BHB (p < 0.01) than multiparous cows. The intervals from calving to first ovulation were not affected by parity; however, primiparous cows showed less abnormal cycles (27.2%) than multiparous cows (50.0%) (p < 0.01). The present study found that a feeding system based on TMR and pasture was sufficient to produce over 25 L of milk per day without extending their calving to first ovulation interval in primiparous and multiparous cows. However, multiparous cows showed a greater imbalance in metabolic and hormonal profiles than primiparous cows, causing abnormal ovarian activity.

The effect of permanent or temporary contact with the lamb and contact with males on the lambing to first ovulation interval in Saint Croix sheep

The effect of suckling and presence of the lamb, or ram, on the lambing to first ovulation interval in Saint Croix sheep was determined. Ten days after lambing 50 ewes and their lambs were assigned to three different suckling treatments: continuous suckling (CS), restricted suckling (RS), restricted lamb presence (RP). Ewes from each treatment were allocated to groups that had contact with a ram (TR) or remained isolated from rams (IR). Therefore, overall, there were six groups with 2 factors: CS-IR (n=7) CS-TR (n=7); RS-IR (n=11); RS-TR (n=11); RP-IR (n=7), and RP-TR (n=7). The presence of the ram (P=0.01) and restricted suckling (P=0.05) reduced the interval from lambing to first ovulation, while no interaction was found (P>0.05) between these two factors. An effect of treatment and its interaction influenced significantly the number of vocalizations and growth rate in lambs. At the day of weaning RP vocalized more than RS (P<0.01), which in turn vocalized more than CS (P<0.01), followed by a general decline to pre-weaning levels 48h later. Lambs in RP had greater growth rate during first 3 d after weaning compared with RS (P<0.05), which displayed greater growth rate that CS (P<0.05). In addition, an effect of treatment (P=0.05) was found in cortisol concentration. Our results indicate that Saint Croix ewes respond to the ram effect in early postpartum, shortening the resumption of postpartum ovarian activity. When this technique is combined with restricted suckling, additional benefits are achieved for lambs with reduced weaning stress.

Reduction of liver function delays resumption of postpartum ovarian activity and alters the synthesis of acute phase proteins in dairy cows

The aim of this study was to evaluate the concentration of acute phase proteins, milk production, and resumption of postpartum ovarian activity of clinically healthy dairy cows in a semi-extensive system with different Liver Functionality Index (LFI) values. The animals were divided into two groups: Low LFI (LLFI: −7 to −12; n: 10) and High LFI (HLFI: −7 to −4; n: 10). Animals with LLFI had lower paraoxonase activity and lower albumin concentration in the pre- and postpartum periods (P<0.05), higher non-esterified fatty acids prepartum (P<0.005), and higher haptoglobin concentration postpartum (P<0.01). The LLFI group showed lower resumption of ovarian activity until 44days postpartum (29%; P<0.05) than HLFI (86%). Milk production did not differ between groups. Therefore, this study suggests that the LFI is an important biomarker of synthesis of acute phase proteins and the first ovulation interval, and it can be used to improve the production and reproductive performance.

Blood metabolite profiles in cycling and non-cycling Friesian-Sanga cross-bred cows grazing natural pasture during the post-partum period.

An experiment was conducted to investigate the effect of plasma concentrations of the metabolic hormones [Growth hormone (GH), insulin and insulin-like growth factor -I (IGF-I)] and nutritional metabolites (Glucose, cholesterol, total protein, albumin, globulin, urea and creatinine) on the resumption of post-partum ovarian activity in sixteen Friesian-Sanga cows grazing extensively on native grassland. Blood samples were taken from cows from week 1 to 16 post-partum. Cows were classified as having resumed ovarian activity when a plasma progesterone concentration of ≥ 1.0 ng/ml was recorded for two consecutive weekly samples. Based on the resumption of ovarian activity, cows were classified as early-cycling, late-cycling or non-cycling. The concentrations of the metabolic hormones were measured from week 1 to 10, while those of the nutritional metabolites were measured during week 1, 3, 5, 7 and 9 during the study period. The concentrations of the metabolic hormones, GH and insulin were similar (p > 0.05) in the three ovarian activity groups, likewise the concentrations of the nutritional metabolites, glucose, total protein, globulin, urea and creatinine. Plasma IGF-I concentration was higher (p < 0.001) in early-cycling (18.7 ± 0.74 ng/ml) than in late-cycling (12.4 ± 0.75 ng/ml) and non-cycling (10.4 ± 0.91 ng/ml) cows. Plasma cholesterol concentrations were significantly lower (p < 0.05) in early-cycling (1.94 ± 0.15 mmol/l) compared with late-cycling (2.48 ± 0.12 mmol/l) and non-cycling (2.61 ± 0.11 mmol/l) cows. For plasma albumin concentrations, the levels recorded for early-cycling cows were higher (40.7 ± 2.85 g/l) than in late-cycling (34.4 ± 1.97 g/l) and non-cycling (33.6 ± 2.66) cows. The results suggest that cows with lower plasma concentrations of IGF-I and albumin, but higher plasma cholesterol concentrations were at risk of delayed resumption of post-partum ovarian activity.

Effect of supplementary feeding of glucogenic and lipogenic diet on body parameters and onset of ovarian cyclicity in postpartum dairy buffaloes

The present study was undertaken to assess the effect of supplementation of glucogenic and lipogenic diets on certain physical parameters and onset of postpartum ovarian cyclicity in dairy buffaloes. Healthy postpartum pluriparous Murrah buffaloes (30) were classified into group 1, buffaloes (10) were supplemented with glucogenic precursor in addition to routine feeding; group 2, buffaloes (10) with rumen by-pass fat in addition to routine feeding; and group 3 buffaloes (10) maintained on routine diet without any additional supplementation served as control. The BCS was significantly high in group 2 buffaloes than in group 1 and group 3 buffaloes. Supplemented compared to control counterparts had significantly higher BW and BFT. The resumption of postpartum ovarian activity was influenced by nutrition. Group 2 and 1 buffaloes experienced early onset of first postpartum estrus than group 3 buffaloes. Thus, it can be recommended to supplement the diet with high energy rations in the early postpartum period to improve the reproductive efficiency of buffaloes.

Plasma thiobarbituric acid reactive substances, vitamin A and vitamin E levels and resumption of postpartum ovarian activity in dairy cows

Vitamins with antioxidative functions are commonly used as supplements to improve fertility in dairy cows. However, according to field test results uncertainty exists about the effect of these vitamins, especially in vitamin A and vitamin E, on ovarian functional activity. This study was performed to reveal the physiological characteristics of cows receiving enough feed and the ovaries of which were activated in the early postpartum period. Six of 12 primiparous cows showing the corpus luteum on 25 to 27 days after parturition were classified as early responders (PER); the remaining six were classified as late responders (PLR). Among 11 multiparous cows, nine were early responders (MER), and the remaining two were late responders (MLR). Plasma concentration of thiobarbituric acid reactive substances (TBARS) in the PER were lower than those in the PLR (P<0.01). The ratio of plasma all-trans-retinol to intake α-tocopherol or β-carotene were increased in the following order: MER<PER<PLR (P<0.01). The milk lactose (P<0.025) and plasma glucose (P<0.01) of the early responders tended to be lower than those of the late responders. These may have been associated with the availability of vitamins or energy balance. Thus, we suggest the possibility that the cows which were able to utilize antioxidants and energy from the feed efficiently may have earlier resumption of ovaries postpartum.

Associations between resumption of postpartum ovarian activity, uterine health and concentrations of metabolites and acute phase proteins during the transition period in Holstein cows

The resumption of ovarian activity, uterine health, severity of the negative energy balance and the synthesis of inflammatory mediators during the transition period in dairy cows are interrelated. Therefore, the aim of this study was to evaluate the association between the resumption of postpartum ovarian activity and the percentage of polymorphonuclear (PMN) cells in endometrial cytology, lipid mobilization and the secretion of acute phase proteins. For this study, 20 multiparous Holstein cows were used. Blood samples that were collected from 21d before calving to 44d in milk (DIM) were analyzed for serum glucose, non-esterified fatty acids (NEFA), insulin, haptoglobin, albumin, paraoxonase and progesterone. Endometrial cytology was performed at 37±2DIM to evaluate the percentage of PMN cells in the uterine flushing. Cows were divided into two groups: (1) ovulatory cows (n=12), which returned to ovarian activity by 44±2DIM; and (2) anovulatory cows (n=8), which did not resume ovarian activity during this period. Ovulatory cows had a lower (P=0.05) percentage of PMN cells in endometrial cytology than anovulatory cows (26.3±8.3% vs. 53.4±16.9%, respectively). Ovulatory cows had higher serum albumin during the pre- (P=0.03) and postpartum periods (P=0.01), and tended to have lower haptoglobin concentrations in the prepartum period (P=0.07) and higher paraoxonase activity in the postpartum period (P=0.09). In conclusion, cows that resumed ovarian activity early in the postpartum period had higher albumin concentrations in the peripartum period, which were associated with a lower percentage of uterine PMN cells.

Effect of genetic merit for energy balance on luteal activity and subsequent reproductive performance in primiparous Holstein-Friesian cows

Postpartum energy status is critically important to fertility. However, studies dealing with the relationship between both traits are rare and most refer only to the phenotypic level. In this study, random regression models were used to generate cow-specific lactation curves for daily breeding values (BV) of energy balance (EB) to assess the effect of genetic merit for energy status on different traits derived from progesterone profiles and on subsequent reproductive performance of high-producing dairy cows. Individual feed intake, milk yield, and live weight were recorded for lactationd 11 to 180, and EB was estimated on a daily basis. The results provided the basis for the estimation of BV for 824 primiparous Holstein-Friesian cows. For a subset of these cows (n=334), progesterone profiles for the resumption of ovarian activity were available. Four different traits describing the genetic merit for EB were defined to evaluate their relationship with fertility. Two EB traits referred to the period in which the average daily EB across all cows was negative (d 11 to 55 postpartum), and 2 parameters were designed considering only daily BV for d 11 to 180 in lactation that were negative. We found that cows with a high genetic merit for EB had a significantly earlier resumption of ovarian activity postpartum. Thus, an EB (indicator) trait should be included in future breeding programs to reduce the currently prolonged anovulatory intervals after parturition.

Associations of prepartum body condition score with occurrence of clinical endometritis and resumption of postpartum ovarian activity in dairy cattle

This study was performed to investigate the effect of periparturient body condition score on the occurrence of clinical endometritis and postpartum resumption of ovarian activity in dairy cows. Eighty-seven lactating Holstein cows, fed with a total mixed ration diet, were included into the study. Body condition scoring (using a 5-point scale with quarter-point divisions) was performed by the same investigator using the visual technique every 2weeks, from 2weeks before until 6weeks after calving. Palpation of the reproductive tract and ultrasonographic assessment of ovaries for detection of corpus luteum using a rectal linear probe was also performed at 2, 4, and 6weeks after calving. Cows with clinical endometritis had significantly lower body condition score (BCS) than normal cows at all weeks pre- and postcalving, and cows that did not ovulate until 45days after calving had a significantly lower BCS pre- and postpartum. Cows that did not ovulate until 45days after calving also lost more BCS from 2weeks before to 4weeks after calving. Besides, first ovulation after calving take occurred later in cows with clinical endometritis compared to normal cows (P < 0.05). In conclusion, low BCS is a risk factor for postpartum endometritis and delayed cyclicity in dairy cows. BCS loss from dry-off to early lactation and occurrence of clinical endometritis can significantly affect postpartum ovarian activity.

Effect of Body Condition Score and Parity on Resumption of Postpartum Ovarian Activity in Montberliard Dairy Cows in Algerian Semi -Arid Area

A study was undertaken to evaluate the relationships between body condition score (BCS), parity and serum hormonal profiles (progesterone (P4) and estradiol -17β (E2)), and resumption of postpartum ovarian cyclicity on (primiparous (n=19) and multiparous (n=59) Montbeliard cows. The BCS was measured at calving, using a 1 to 5 point scale according to the Edmonson (1989) method. Blood samples were collected by jugular venous at 30 d, 40 d, 50 d and 60 d postpartum (10 days of interval). Serum hormonal analysis were determined by chimiluminescent Immuno-Assay (CLIA). Changes in progesterone concentration were exploited to assess the resumption of ovarian cyclicity. The results showed a significant increase in progesterone and estradiol -17β serum levels during postpartum period. The correlation analysis showed that P4concentration in cows was positively correlated with their BCS at 30 d, 40 d, 50 d and 60 d postpartum (r =0.630; r = 0.603; r = 0.622 and r = 0.467 respectively; P<0.01). Additionally, the BCS at calving was positively correlated with estradiol -17β concentration at 30 d (r= 0.628); 40 d (r= 0.612); 50 d (r= 0.444) and 60 d (r=0.294) (P<0.01). Furthermore, BCS at calving was strongly but negatively correlated with CCI (r= 0.704; P<0.01). The results of the current study provide an evidence of a negative correlation between calving conception interval and secretion of P4 and E2.

Fecal progestins during pregnancy and postpartum periods of captive red brocket deer (Mazama americana)

This study aimed to validate the enzyme immunoassay (EIA) for fecal progestin quantification of the species Mazama americana, define its excretion profile during periods of gestation and postpartum and determine the gestation period and resumption of postpartum ovarian activity in this species in captivity. Fecal samples were collected twice a week during gestation and every day in the postpartum period, and analyzed using EIA. The mean concentrations (±SEM) of fecal progestins during gestation were 2180.0±299.1ng/g in early pregnancy (week 1–11), 3271.4±406.9ng/g in middle pregnancy (week 12–22) and 5592.0±1125.8ng/g in late pregnancy (week 23–32). The gestation period determined for the species was 220.9±1.2 days. The concentration of progestins reached its peak prior to parturition and returned to baseline levels in 4±0.31 days after parturition. In the postpartum period, the mean concentrations of fecal progestins were 1564.2±182.6ng/g in the interval between parturition and resumption of ovarian activity, 469.8±24.5ng/g in the inter-luteal phase and 2401.7±318.5ng/g during the luteal phase, such that the postpartum period and the luteal phase differed from the inter-luteal phase. Fecal progestin profiling permitted the detection of ovulation 26.9±3.4 days after parturition in all the hinds studied and estimation of the mean duration of the estrous cycle, 21.3±1.1 days. Analysis established that concentrations of progestins above 3038.76ng/g diagnosed pregnancy, a value determined from the week 12 of gestation. Moreover, the quantification of fecal progestins by EIA proved to be an important tool for noninvasive endocrine monitoring and to obtain reproductive data on the species M. americana in captivity.

Metabolic and energy status during the dry period is crucial for the resumption of ovarian activity postpartum in dairy cows

It is well known that the degree of negative energy balance in high-producing dairy cows is the major cause of delayed resumption of the ovarian cyclicity that closely relates to fertility. Recent evidence suggests that the energetic situation during early lactation critically affects nutrient partitioning, metabolism, and the reproductive axis, whereas the effect of energy status during the dry period is widely unknown. The aim of the present study was to investigate the effect of energy status throughout the entire dry period until early lactation on the onset of the ovarian cyclicity. Blood samples were taken in 23 cows from dry off at 8wk before expected parturition to 8wk postpartum for the analyses of metabolites and hormones, and milk samples were obtained 3 times weekly from d 7 of lactation onward to confirm luteal activity and pregnancy by milk progesterone analysis. Energy balance (EB) was measured weekly during the last 6wk of the dry period and every other week after parturition. Liver biopsies were obtained at 8wk before expected calving, within 1 d after calving, and at 4wk postpartum to measure the mRNA abundance of various gluconeogenic enzymes and metabolic hormone receptors. Cows showing luteal activity within 3wk postpartum were defined as ovulatory during the first follicular wave postpartum (OC), whereas cows without luteal activity within 3wk postpartum were defined as anovulatory (AC). Energy balance and, concomitantly, plasma concentrations of glucose, insulin, insulin-like growth factor-1, 3,5,3′-triiodothyronine, and thyroxine were higher in OC than in AC during the dry period. Plasma thyroxine concentrations and body condition score during the postpartum period were higher in OC than in AC. At the mRNA level (19 cows), hepatic insulin receptor decreased from dry off to early lactation, and mRNA of pyruvate carboxylase was highest at parturition and decreased in early lactation in AC only, whereas both parameters remained unchanged in OC. The mRNA abundance of phosphoenolpyruvate carboxykinase-mitochondrial increased from dry off to parturition in both groups, remained high in OC, and decreased again in early lactation in AC. However, none of the investigated gene transcripts differed between OC and AC cows. Thus, ovarian function postpartum appears to be crucially influenced by the energy status during the dry period, which is reflected by timely changes in hepatic mRNA abundance of only a few key metabolic factors in the liver.

Resumption of post-partum ovarian activity in three different dairy breeds in the mountainous and forest areas in North West of Tunisia

Resumption of post-partum ovarian activity in three different dairy breeds in the mountainous and forest areas in North West of Tunisia

Effect of season and photoperiod on the time of first postpartum ovulation in Awassi ewes

Seasonal differences in the resumption of postpartum ovarian activity, milk production and periparturient metabolic status were investigated in lactating non-suckling dairy Awassi sheep in two consecutive experiments. In Experiment 1, autumn-lambing (AL, n = 27) and spring-lambing (SL, n = 37) ewes were investigated. Ovarian activity was monitored by means of individual progesterone (P4) profiles from day 5 to day 100 post partum. Most of the AL dams (89%) ovulated till day 35 after parturition and became cyclic thereafter. Incidence of persistent corpus luteum (CLP) and short luteal phases (sCL) was frequent (18% and 29%, respectively) among non-conceiving dams. In contrast, only 24% of the SL ewes ovulated before day 35. P4 levels during the luteal phase were lower in cyclic animals, and the cycle was longer in SL than in AL animals. No CLP or sCL was detected in the spring-lambing group, and 61% of SL ewes remained acyclic till the end of the trial. Lactation length was significantly longer in SL dams than in AL ewes (P = 0.008). According to the plasma metabolites (BHB, NEFA) and metabolic hormones (insulin, IGF-I, thyroxine) examined, negative energy balance did not appear in any of the animals. However, seasonal differences were seen in IGF-I and thyroxine levels, which were higher in the SL dams. In Experiment 2, influence of additional lighting was studied in autumn-lambing ewes. The long-day photoperiod (LD, n = 23) group was exposed to artificial light from sunset till midnight (approx. 16 h light/8 h dark) from some weeks before the expected date of delivery in mid-September until the end of December. The control group (n = 25) experienced only natural daylength. The first postpartum ovulation tended to occur later in the LD animals than in the controls (P = 0.047). The lactation of the LD group tended to be longer (P = 0.061). NEFA, BHB, insulin, IGF-I and thyroxine levels did not differ between the groups. (i) The ovarian function of the Awassi population is seasonal under temperate continental climate conditions. (ii) The first postpartum ovulation of non-suckling, autumn-lambing dams may occur very early, even before the completion of uterine involution. (iii) Additional artificial lighting may delay the time of first postpartum ovulation in AL ewes. (iv) Postpartum negative energy balance is unlikely to occur in dairy Awassi ewes even in high-producing intensive systems.