Resumption Of Postpartum Ovarian Cyclicity Research Articles

Fibroblast Growth Factor 21 Has a Diverse Role in Energetic and Reproductive Physiological Functions of Female Beef Cattle.

Fibroblast growth factor 21 (FGF21) has been identified in multiple mammalian species as a molecular marker of energy metabolism while also providing negative feedback to the gonads. However, the role of FGF21 in regulating the energetic and reproductive physiology of beef heifers and cows has yet to be characterized. Herein, we investigated the temporal concentrations of FGF21 in female beef cattle from the prepubertal period to early lactation. Circulating concentrations of FGF21, non-esterified fatty acids, plasma urea nitrogen, glucose, and progesterone were assessed. Ultrasonography was employed to determine the onset of puberty and resumption of postpartum ovarian cyclicity as well as to measure backfat thickness. Finally, cows and calves underwent the weigh-suckle-weigh technique to estimate rate of milk production. We have revealed that FGF21 has an expansive role in the physiology of female beef cattle, including pubertal onset, adaptation to nutritional transition, rate of body weight gain, circulating markers of metabolism, and rate of milk production. In conclusion, FGF21 plays a role in physiological functions in beef cattle that can be applied to advance the understanding of basic scientific processes governing the nutritional regulation of reproductive function but also provides a novel means for beef cattle producers to select parameters of financial interest.

Effect of weaning on performance of dairy buffaloes in tropical conditions - A review

Weaning is one of the important management practices, which is mostly followed at organized dairy farms in India and abroad. Generally breeding programme at buffalo farms focusses on milk production, however weaning can additionally boost the total milk production of the dairy farm, apart from increasing the reproductive potential of adults and promoting scientific rearing of young calves. There is little information on early weaning of buffalo calves and its effect on production and reproduction performances of dams during post-partum in Indian buffaloes. However, early weaning may be associated with the restriction of colostrum feeding and essential nutrients for dairy buffalo calves. Breaking the maternal bond is stressful to the calf and lactating buffaloes, which can be evaluated by biochemical indicators of stress in bovine models. Although, weaning at birth is well established in dairy cattle, in case of buffaloes, it may yield significant outcomes in terms of estimating actual milk production and increasing precious buffalo milk in the market for human consumption. On the other hand, weaning practice in dairy buffaloes has been limitedly investigated and not reviewed properly under variable conditions. Keeping in view the impact of weaning, the present paper has been aimed to review the effect of weaning on performance of dairy buffaloes under tropical conditions. The weaning practices in dairy buffaloes can reduce the feeding cost of calves and increase the reproductive potential of the dairy animals through early resumption of post-partum ovarian cyclicity. However, more trials need to be conducted in dairy buffaloes for understanding the relationship between the behaviour of weaned animals and age of weaning towards better adaptability and optimum production at dairy farms.

Resumption of postpartum ovarian cyclicity in winter-lambing Lohi sheep (Ovis aries)

The postpartum ovarian cyclicity which is associated with uterine involution has significant importance in fertility of sheep. The study was conducted to estimate the postpartum resumption of ovarian cyclicity in Lohi sheep during winter lambing season. Twelve pregnant ewes were selected. The commencement of ovarian cyclicity was investigated in postpartum ewes by estimating progesterone (P4) concentration in blood samples collected on weekly intervals starting from day of parturition till 12th week of postpartum. On the day of parturition, mean P4 concentration was 0.38 ± 0.08 ng / mL. After that, P4 level raised to 0.70 ± 0.13 and 0.83 ± 0.13 ng / mL during 1st and 2nd weeks respectively. During 3rd week, P4 concentration was 1.02 ± 0.18 ng / mL (ovulation). The peak P4 level during first estrous cycle was 3.02 ± 0.8 ng / mL and detected on 5th week. Second ovulation was observed during 6th week and again peak P4 concentration of 2nd cycle was found as 2.5 ± 0.64 ng / mL on 7th week. Based upon the hormonal profile, it was concluded that postpartum ovarian cyclicity resumed on 3rd week of postpartum in winter lambed Lohi sheep.

Effect of linseed feeding on blood metabolites, incidence of cystic follicles, and productive and reproductive performance in fresh Holstein dairy cows

This study was done to investigate the effect of feeding linseed on blood metabolites, incidence of cystic follicles, resumption of postpartum ovarian cyclicity, pregnancy rate, milk production, and composition in fresh Holstein dairy cows. A total of 399 dairy cows were assigned randomly to 2 diets. Diets contained either protected palm oil (CON) or extruded linseed (LIN) and were fed from calving to d 40 postpartum. Ovaries of each cow were examined on d 10, 20, 30, and 40 after parturition (parturition=d 0) by transrectal ultrasonography to determine follicular development, ovarian disorders, and cyclicity. Blood samples were collected at 14-d intervals for 6 wk starting on the day of parturition to determine plasma concentrations of glucose, β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), and blood urea N (BUN). Results showed plasma glucose concentration was affected by the diets and was greater in the LIN treatment, but BHBA, NEFA, and BUN concentrations were similar among treatments. Dietary treatments had no significant effect on milk production and composition except milk fat percentage that significantly decreased in cows fed LIN (3.55%) compared with those fed with CON (4.17%). Plasma progesterone concentrations were greater in LIN treatment than CON treatment (1.31±0.09 vs. 0.87±0.09) at early postpartum. The resumption of cyclicity and onset of estrus were influenced by treatments and reduced by 7 d in LIN treatment compared with CON treatment. Cows fed diets enriched in LIN fatty acids had a lesser incidence of cystic follicles. Treatments did not differ significantly in terms of the number of days open, number of services per pregnancy, and pregnancy rate. In conclusion, feeding linseed immediately after parturition decreased milk fat and incidence of cystic follicles, increased progesterone concentrations early postpartum, and caused earlier resumption of cyclicity but did not affect pregnancy rate.

Blood metabolite concentrations and postpartum resumption of ovarian cyclicity in Sanga cows

Blood metabolite concentrations and postpartum resumption of ovarian cyclicity in Sanga cowsAn experiment was conducted to investigate the effect of concentrations of certain blood nutrient-sensitive metabolites and the resumption of postpartum ovarian cyclicity in 16 Sanga cows (mean BCS 5). Blood samples were taken from cows from weeks 1 to 13 (90 days) postpartum, processed and the plasma progesterone concentration measured to determine the resumption of postpartum ovarian cyclicity. The cows were classified as having resumed ovarian cyclicity 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 plasma glucose, cholesterol, total protein, albumin and globulin concentrations recorded were similar in the early cycling, late cycling and non-cycling cows. The mean blood glucose, cholesterol, total protein, albumin and globulin concentrations were 3.60 mmol/L, 2.47 mmol/L, 83.1 g/L, 29.9 g/L and 52.9 g/L, respectively. Plasma urea concentrations in late (6.57 ± 0.17 mmol/L) and non-cycling (6.59 ± 0.17 mmol/L) cows were higher than in the early cycling (5.99 ± 0.17 mmol/L) cows in weeks 1 to 13 postpartum. In addition, the plasma creatinine concentration in the early cycling cows was higher than in late cycling cows (101.8 ± 1.82 versus 94.0 ± 1.99 mmol/L). Cows with higher plasma concentrations of urea and lower creatinine concentrations were at risk of delayed resumption of postpartum ovarian cyclicity. Results suggest poor nutritional status, especially energy deficiency, as a major underlying factor suppressing the postpartum resumption of ovarian cyclicity. Keywords : BCS, creatinine, cycling cows, plasma, postpartum, urea

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.

Nutritional regulation of body condition score at the initiation of the transition period in primiparous and multiparous dairy cows under grazing conditions: milk production, resumption of post-partum ovarian cyclicity and metabolic parameters

The objective of this study was to investigate the effect of different body condition score (BCS) at 30 days before calving (−30 days) induced by a differential nutritional management from −100 days until −30 days on productive parameters, the interval to first ovulation and blood parameters in primiparous and multiparous Holstein cows under grazing conditions until 60 days post partum. The experimental arrangement was a randomized complete block design, where cows were blocked according to BW and expected calving date and then randomly assigned to different nutritional treatments from –100 to –30 days relative to calving to induce different BCS. As the assignment of cows to treatments was random, cows had to lose, maintain or gain BCS; thus, different planes of nutrition were offered with approximately 7, 14 or 20 kg dry matter per day. The BCS score was assessed every 15 days and animals were reassigned in order to achieve the desired BCS at –30 days. Only animals that responded to nutritional treatment were considered and this was defined as follows: primiparous and multiparous high cows (PH and MH) had to gain 0.5 points of BCS, primiparous low (PL) had to lose 0.5 points of BCS and multiparous low (ML) had to maintain BCS at least in two subsequent observations from −100 to −30 days. From −30 days to calving, primiparous and multiparous cows (P and M cows) were managed separately and cows were offered a diet once a day. From calving to 60 days post partum, cows of different groups grazed in separate plots a second year pasture. Cows were also supplemented individually with whole-plant maize silage and commercial concentrate. Cows had similar BCS at −100 days and differed after the nutritional treatment; however, all groups presented similar BCS at 21 days post partum. The daily milk production and milk yield at 60 days post partum was higher in M than P cows. The percentage of milk fat was higher in PH cows compared with PL cows. Concentrations of non-esterified fatty acids (NEFA) were affected by the BCS at −30 days within parity, and in PH cows the concentration of NEFA was higher than in PL cows. The concentrations of total protein were higher in M cows. A lower probability of cycling was found in PL than in PH cows (P < 0.05) and in ML than in MH cows (P < 0.05). Treatment affected various endocrine/metabolic profiles according to parity, suggesting that the metabolic reserves signal the productive/reproductive axis so as to induce a differential nutrient partitioning in adult v. first-calving cows.

Resumption of postpartum ovarian cyclicity after different suckling manipulation treatments in primiparous beef cows

The aims of this experiment were to study suckling manipulation strategies, such as early weaning, suckling inhibition with nose plates or temporary weaning for 5 days, on resumption of ovarian cyclicity in anoestrous beef cows. Seventy-four primiparous Aberdeen Angus and Hereford cows with a mean body condition score of 3.8 ± 0.1 (mean ± s.e.m, 1–8 scale) grazing together on rangeland were used. At 71 days postpartum (Day 0) animals were assigned to one of four groups as follows: (1) suckling group (S, n = 14): cows were suckled throughout all the experiment; (2) nose plates group (NP, n = 20): nose plates were placed to calves for 14 days; (3) temporary weaning group (TW5d, n = 20): calves were isolated from their dams for 5 days; (4) early weaning group (EW, n = 20): calves were definitely weaned. After treatments, weekly serum progesterone concentrations were measured for 9 weeks. EW and NP cows had shorter intervals between treatments and resumption of ovarian cyclicity (19.6 ± 1.7 and 24.5 ± 3.3 days versus 40.6 ± 3.5 and 37.5 ± 4.0 days for EW, NP, TW5d and S, respectively, P &lt; 0.01). A higher proportion of the EW group showed luteal progesterone concentrations the first week after treatments (20 versus 5, 0 and 0% for EW, NP, TW5d and S, respectively, P &lt; 0.05), then proportions of EW and NP cows resuming postpartum cyclicity were similar throughout the remainder of the study. Temporary weaning for 5 days showed no effects on ovarian cyclicity resumption. When body condition score is not very limiting, restricting suckling over 14 days with nose plates is a useful strategy to induce postpartum cyclicity in range cow herds with effects similar to early weaning.

Does breed affect nursing and reproductive behaviour in beef cattle?

This experiment was designed to assess the role of genetic differences in nursing behaviour and the resumption of post-partum ovarian cyclicity of beef cows with different types of calf management. Twenty-four multiparous winter-calving cows, 12 Parda de Montaña (PA) and 12 Pirenaica (PI), were randomly assigned to once-daily restricted nursing during 30 min (RESTR) or ad libitum nursing (ADLIB). Cow-calf behaviour was recorded at weeks 3, 8 and 13 of lactation. Results were compared within suckling system. Twice-weekly blood samples were drawn throughout lactation to analyse progesterone as an indicator of ovulation. Within each type of calf management, both breeds nursed their calves for a similar amount of time (23.0 and 57.2 min in PA vs. 25.9 and 59.0 min in PI, when nursing once daily or ad libitum, respectively; P &gt; 0.10). Furthermore, ovarian cyclicity was initiated at a similar time after calving between breeds (70 vs. 73 d in PA and PI, respectively), although it was shorter in RESTR than in ADLIB (54 vs. 89 d; P &lt; 0.001). Key words: Beef cattle, calf management, restricted nursing, post-partum anoestrus

Field Trial on Progesterone Cycles, Metabolic Profiles, Body Condition Score and their Relation to Fertility in Estonian Holstein Dairy Cows

Resumption of luteal activity postpartum and fertility were investigated in an Estonian Holstein high milk production and good fertility dairy herd. Body condition was scored after every 10 days in 54 multiparous dairy cows (71 lactations) calving inside from December to March during 4-year period. Blood samples were taken 1-14 days before calving and 1-14, 28-42 and 63-77 days after calving: analytes estimated were serum aspartate aminotransferase (AST), glucose, ketone bodies, total cholesterol, non-esterified fatty acids and triglycerides. The general linear mixed model was used to compare the data for cows with different characteristics in luteal activity postpartum based on their milk progesterone profiles. Forty-five per cent of cases had abnormal profiles; delayed resumption of ovarian cyclicity postpartum (DC) was the most prevalent abnormality. There was no difference in body condition scores between the groups. The DC and prolonged luteal phase groups had higher serum AST activity (p < 0.01) 1-14 days postpartum compared with normal group. The DC group also had higher cholesterol and triglyceride values (p < 0.05) 28-42 days postpartum and higher milk fat/protein ratio (p < 0.01) on the first month of lactation compared with normal profile group. Despite long post-calving anoestrous period (71 +/- 5.0 days; mean +/- SEM) DC group had 64.7% first service pregnancy rate (normal group 48.6% and PLP group 37.5%). This study did not find any detrimental effect of prolonged anovulatory period postpartum on subsequent fertility.

Whole sunflower seeds as a source of polyunsaturated fatty acids for grazing dairy cows: Effects on metabolic profiles and resumption of postpartum ovarian cyclicity

Intake of polyunsaturated fatty acids (PUFA) could modify follicular dynamics and reduce the length of the interval from calving to first ovulation (ICOV) in dairy cows, associated with changes in metabolites (i.e. cholesterol) or hormones (i.e. IGF-I). To test this hypothesis, 48 cows were stratified in two groups (primiparous or multiparous) and within each group were randomly assigned to three treatments to begin at calving: 0 kg (SS0), 0.7 kg (SS0.7) and 1.4 kg (SS1.4) of whole sunflower seeds (WSS) per cow per day. The experimental period lasted for 60 days after calving and the diets, which consisted of direct grazing of improved pastures, whole-plant wheat silage and concentrates, were designed to be isocaloric and isoproteic (1.6 Mcal NEL/kg DM, 16.7% CP). Ovaries were examined by ultrasound three times per week from day 8 postpartum (PP) until first PP ovulation. Body condition score (BCS) was determined and blood samples were collected weekly from calving to characterize the metabolic profiles. In treatments SS0.7 and SS1.4, 7/8 and 6/8 primiparous cows ovulated the first follicular wave PP, compared with only 1/8 primiparous cow in treatment SS0, while there were no treatment differences in multiparous cows. The ICOV was 44, 21 and 19 days for the primiparous, and 22, 21 and 25 days for the multiparous cows, in treatments SS0, SS0.7 and SS1.4, respectively. Treatments had no effect on BCS, plasma IGF-I and metabolic profiles except that NEFA and urea were increased by WSS supplementation. Intake of PUFA (WSS up to 1.4 kg/day or 6.7% of the diet) during early lactation reduced the ICOV in primiparous grazing dairy cows in early lactation but not in multiparous cows, and while the precise mechanism for these results is unclear, it was not related to changes in the plasma concentrations of IGF-I or cholesterol.

Ovarian Cyclicity and Reproductive Performance of Holstein Cows Carrying the Mutation of Complex Vertebral Malformation in Japan

This study was carried out on 71 lactating Holstein Friesian cows to investigate the resumption of ovarian cyclicity postpartum and the reproductive performance in cows carrying the mutation of complex vertebral malformation (CVM) compared with control ones. The cows were distributed in two dairy farms in Hiroshima Prefecture, Western Japan. Blood samples were collected from the cows to detect carrier cows with CVM mutation. Furthermore, plasma samples were collected weekly after calving from control cows (n = 10) and CVM carrier cows (n = 10), until 10 weeks postpartum to investigate the day of first ovulation and the resumption of ovarian cyclicity postpartum. The reproductive parameters were investigated and compared with control and CVM carrier cows. Thirty-six cows were diagnosed to be CVM carriers by DNA examination and confirmed later by DNA sequencing. The pedigree analysis of the carrier cows revealed that they were daughters of six types of CVM carrier semen that still was used in dairy farms in Western Japan. In terms of reproductive indices, there were no significant differences between the control and the CVM carrier cows on the day of the first ovulation postpartum and the interval from calving to first insemination. However, CVM carrier cows significantly required more inseminations per conception and showed a significantly longer period to conception and subsequent calving than control ones. In conclusion, the reproductive performance of the CVM carrier cows was lowered through conception failure that might indicate the occurrence of intra-uterine mortality in those cows.

Prostaglandins and reproduction in female farm animals

Prostaglandins impact on ovarian, uterine, placental, and pituitary function to regulate reproduction in female livestock. They play important roles in ovulation, luteal function, maternal recognition of pregnancy, implantation, maintenance of gestation, microbial-induced abortion, parturition, postpartum uterine and ovarian infections, and resumption of postpartum ovarian cyclicity. Prostaglandins have both positive and negative effects on reproduction; they are used to synchronize oestrus, terminate pseudopregnancy in mares, induce parturition, and treat retained placenta, luteinized cysts, pyometra, and chronic endometritis. Improved therapeutic uses for prostaglandins will be developed when we understand better their involvement in implantation, maintenance of luteal function, and establishment and maintenance of pregnancy.

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 ≤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 ≤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 ≥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 ≥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.

The Acyclic Period Postpartum in Automatic and Conventional Milking

The acyclic postpartum period in cows is prolonged due to frequent suckling when compared with twice daily milking. In conventional milking systems twice daily milking is common, while in automatic milking systems (AMS) three or more milkings are performed in early lactation. In this study, the hypothesis was tested that an increased milking frequency in AMS causes a delay in resumption of ovarian cyclicity postpartum and increases days open in German Fleckvieh cows (n = 124). Calvings were equally distributed throughout the 1-year experimental period. All cows were housed in one barn. Sixty-three cows were milked in an AMS (AC) and 61 cows were twice daily milked in a conventional milking parlour (PC). Forty-two AC and 36 PC remained in the herd until conception. After parturition, milk samples were analysed for progesterone twice weekly to record the ovarian activity until pregnancy was diagnosed. The first and the second ovulation were determined by the progesterone profile of each individual cow. The mean milking frequency during the first 3 weeks after parturition was higher in AC (3.17 +/- 0.09 milkings/day) than in PC (milked twice daily). The individual mean milking frequency of AC for the first 3 weeks of lactation ranged from 2.0 to 5.9 daily milkings. The time span from parturition until the first and second ovulation did not differ between AC and PC. However, first ovulation was observed earlier in primiparous (23 +/- 1 days) than in multiparous cows (29 +/- 1 days, P < 0.05). Within AC no relationship between milking frequency and duration of the acyclic period was observed. Days open did not significantly differ between AC and PC and between primiparous and multiparous cows. In conclusion, the increased milking frequency in AMS did neither cause a delay in resumption of ovarian cyclicity postpartum nor did it increase days open.

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.

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 ≥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.

Postpartum Reproductive Function: Association with Energy, Metabolic and Endocrine Status in High Yielding Dairy Cows

The effect of energetic, metabolic and endocrine status upon onset of ovarian cyclicity as well as time empty and conception at first service was assessed in 90 multiparous Holstein cows (mean 9'500 kg energy-corrected milk/305 d) in a research farm in Switzerland. Dry matter intake, milk yield and body weight were measured daily from week 2 antepartum (a.p.) through wk 20 postpartum (p.p.). Milk composition was determined 4 times/wk and milk acetone was measured weekly. Blood samples for the determination of glucose, non-esterified fatty acids (NEFA), cholesterol, creatinine, albumin, urea, s-hydroxybutyrate (BHBA), leptin, insulin, insulin-like growth factor-1 (IGF-1), growth hormone, 3,5,3'-triiodothyronine (T 3 ) and thyroxine (T 4 ) concentrations, and of activities of aspartate amino transferase (ASAT), lactate dehydrogenase (LDH) and glutamate dehydrogenase (GLDH) were taken 2 wk a.p. and in wk 1-16 and 20 p.p. between 0730-0900. Cows were gynaecologically examined weekly. The onset of first ovulation was specified by skim milk progesterone determination by a radioimmunoassay (twice/wk) and by rectal palpation. Energy balance (EB) traits were calculated and expressed as accumulated negative EB from parturition to EB equilibrium (AUC), EB nadir (EBN), rate of EB recovery following EBN (EBR), time from parturition to EBN (DEBN), and time from parturition to EB equilibrium (DEBE). Results: Resumption of ovarian cyclicity postpartum was not reflected by any of the EB traits. However, a small degree of EBN and a fast EBR were related to a short period from parturition to conception. Survival analysis with timevarying covariates revealed that high plasma concentrations of T 3 and T 4 p.p. were significantly associated with a high chance of an early start of the ovarian cycle, and high concentrations of glucose and cholesterol were associated with a short time empty, respectively. Conception at first service was positively associated with EB at first service and with progesterone concentration at 10-13 d after first service. However, leptin, as most other metabolic and endocrine traits, was not associated with any of the reproductive traits. In conclusion, thyroid hormones may play an important role in the onset of the ovarian cycle p.p., and a good energy status enhances the chance of conception at first service and shortens time empty.

Serum cholesterol and triglycerides in postpartum beef cows and their relationship to the resumption of ovulation

The variations in lipid metabolism according to the physiological stage and their relationship to the resumption of postpartum ovarian cyclicity were assessed in Limousine beef cows fed a grass diet over 3 yr. Weekly blood samples were collected from 59 cows beginning 10 wk before to 20 wk after calving to evaluate serum cholesterol and triglyceride concentrations and electrophoretic lipoprotein fractions. After parturition, progesterone concentrations were also measured at weekly intervals to determine time of resumption of ovulation. Cows were categorized by resumption of postpartum ovarian cyclicity into 3 groups : early (4 to 6 wk post partum, n=36); mid (7 to 10 wk post partum, n=46) and late (after 11 wk post partum, n=38). Higher serum triglyceride values (P<0.05) were observed during the last 10 wk of pregnancy (0.36 ± 0.15 g/L) than during the first 20 wk of suckling (0.29 ± 0.09 g/L). Cholesterol values decreased significantly (P<0.05) at the end of pregnancy, were minimal (1.01 ± 0.03 g/L) at parturition, and increased again up to 9 wk post calving. Increased cholesterolemia and low serum triglyceride values after calving could be linked to the increased bovine α-lipoprotein fraction and decreased β fraction. Serum triglyceride concentrations were not related to the resumption of postpartum ovarian cyclicity. Higher serum cholesterol values were observed from 2 wk before to 4 wk after calving in cows with early rather than mid and late resumption of ovarian cyclicity. Therefore, modifications in lipid metabolism during the puerperium seem to be related to resumption of cyclicity during the early postpartum period.