Postpartum Ovarian Activity Research Articles

Reduced response to an estrous induction program in postpartum beef cows treated with zilpaterol and gaining body weight

In beef cows, reduced energy intake delays first ovulation postpartum and is associated with lesser insulin, IGF-I and leptin concentrations. However, the close relationship among these hormones mask their individual roles in the reinitiation of ovarian activity. A β-adrenergic receptor agonist (βAR) was used to increase body condition score (BCS) and yet reduce body fat and leptin serum concentration to determine the specific role of leptin in the postpartum ovarian activity. Beef cows (n=77) with BCS 3.1±1.4 received 2kg/day of feed containing 0 or 0.15mg/kg of zilpaterol (a synthethic βAR), for 33 days. Estrus was induced with a progestin implant applied for 9 d and cows in estrus were bred by artificial insemination (AI). Zilpaterol administration increased (P<0.05) daily weight gain, muscle depth and BCS, with no changes in back fat depth, reducing fat to muscle ratio (P<0.05). At the time of AI, insulin (38%) and IGF-I (26%) concentrations were less in zilpaterol-treated cows (P<0.05), but leptin concentration was unaffected. Ovulation rate and animal with luteal activity after estrus induction were also reduced by 35% (P=0.05) and 56.5% (P=0.007), respectively, in zilpaterol-treated cows. Logistic regression estimates for BCS (P=0.016) and IGF-I concentration (P=0.03) were positively related with the occurrence of luteal activity. In addition, whilst back fat (P=0.009) had a positive effect on luteal activity, leptin concentration did not show a significant relationship. In conclusion, despite an increase in body weight and a positive change in BCS, the reduction in insulin and IGF-I concentrations, associated with βAR treatment, reduced the response to induction of estrus. However only IGF-I, but not leptin or insulin, significantly influenced the odds for the occurrence of luteal activity after estrous induction in cattle with poor BCS.

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

Effects of energy supplementation on productivity of dual-purpose cows grazing in a silvopastoral system in the tropics

The aim of the present work was to evaluate milk yield, postpartum (pp) ovarian activity and pregnancy rate in dual-purpose cows grazing Cynodon nlemfuensis and browsing L. leucocephala, with or without energy supplementation. Twenty-four Bos taurus × B. indicus cows were divided in two groups from calving to 70 days post-calving: supplemented group (SG) with ground sorghum grain offered at 0.4% of live weight at calving and control group (CG) without supplement. There was a trend for milk yield (kg day(-1)) to be greater (p = 0.08) for SG (10.55 ± 0.51) compared to CG (9.53 ± 0.61), although without differences in fat (0.42 ± 0.02 vs. 0.38 ± 0.03 kg day(-1)), protein (0.29 ± 0.02 vs. 0.29 ± 0.02 kg day(-1)) or lactose (0.49 ± 0.02 vs. 0.49 ± 0.03 kg day(-1)) concentration. Populations of large, medium and small follicles were similar between treatments. Percentage of cows which showed corpus luteum tended to be greater in SG (50%), compared to CG (33%). Supplemented cows tended to have a shorter calving-first corpus luteum interval (40 ± 10 vs. 51 ± 10 days) and had a significantly higher (χ (2) = 0.03) pregnancy rate (42% vs. 0%). It is concluded that energy supplementation helped to improve ovarian activity and pregnancy rate. Since supplementation did not avoid loss of body condition, the higher pregnancy rate in SG suggests beneficial effects of supplementation probably mediated by metabolic hormones.

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.

INVOLUÇÃO UTERINA, ATIVIDADE OVARIANA, PRIMEIRO CIO PÓS-PARTO E DISTÚRBIOS REPRODUTIVOS EM BÚFALAS

The aim of the present study was to evaluate some reproductive characteristics such as uterine involution, ovarian activity and first estrus after parturition, and reproductive disorders in buffaloes reared in the mixed system (floodplain and land / artificial pasture) in an experimental farm of Belém, Pará State, Brazil. A total of 62 female buffaloes and 167 postpartum periods were evaluated between 2002 to 2005 through gynecological and ultrasound examination. Animals were kept on artificial pasture during the rainy season (January-June) whereas on the floodplain areas with excellent availability of pasture during the dry season (July-December). The resumption of ovarian activity, verified by visual observation of the first estrus, was in average 47.06 ± 25.66 days, while the uterine involution verified by rectal palpation and ultrasound examination was 27.5 ± 7.77 days. The number of cases of abortion, retained placenta and embryonic death were 10 (5.90%), 13 (7.78%) and 14 (8.38%) cases, respectively, while the number of cases of uterine infection was 18 (10.7%). Regarding nonfunctional ovaries, 26 (15.56%) cases were found and two (1.19%) cases of ovarian hypoplasia, three (1.79%) cases of ovarian cysts and two (1.19%) cases of salpingitis were observed.KEYWORDS: Buffaloes, postpartum ovarian activity, reproductive disturbances, reproductive efficiency.

Restricted Suckling and Hormonal Treatment on the Postpartum Ovarian Activity Resumption of Beef Cows in the Tropics of Mexico

Restricted Suckling and Hormonal Treatment on the Postpartum Ovarian Activity Resumption of Beef Cows in the Tropics of Mexico

Dairy cows’ reproductive response to feeding level differs according to the reproductive stage and the breed

Reproductive performance has decreased over the last decades in many dairy systems. This study aimed at comparing the effects of a high- and a low-feeding level on reproductive stages (cyclicity, oestrus and fertility) of Holstein and Normande cows in a grass-based winter compact calving system. High-fed cows received a total mixed ration composed of 55% maize silage, 15% dehydrated alfalfa pellets and 30% concentrate in winter and 4 kg/day concentrate supply at grazing. Low-fed cows only received 50% grass silage and 50% haylage in winter and no concentrate at grazing. Low-fed cows produced less milk over 44 weeks, but lost more body condition (BC) than high-fed ones (5207 v. 7457 kg, −1.28 v. −0.96 unit, P < 0.001). Normande cows produced less milk and lost less BC than Holstein ones (5596 v. 7068 kg, −0.89 v. −1.36 unit, P < 0.001). Post-partum ovarian activity was little affected by the feeding level. In both breeds, ovulation detection rate was higher in low-fed cows (74% v. 59%, P < 0.001) and detection relied more frequently on standing behaviour (67% v. 55%, P = 0.022). In both breeds, the recalving rate following the first and second inseminations was not significantly affected by the feeding level, although more non-fertilisations or early embryo mortalities occurred in low-fed cows (43% v. 26%, P = 0.004). For the Holstein breed, this was clearly explained by more late embryo mortalities in high-fed cows (30% v. 9%, P = 0.004). Finally, pregnancy rate by the end of the 13-week breeding period was similar between feeding groups. Conversely, the Normande dual-purpose cows had a higher pregnancy rate by the end of the breeding period than the Holstein dairy cows (72% v. 54%, P = 0.007), owing to a better ovarian activity (79% v. 54% normal, P < 0.001) and a higher recalving rate following insemination (53% v. 37%, P = 0.007). In conclusion, this study demonstrates that feeding levels with converse effects on milk yield and BC score also have converse effects on reproductive stages and lead to quite similar final reproductive performance in compact calving systems. Normande cows benefit from an overall better reproductive performance, but do not suit high feeding levels for very compact calving systems owing to depressed oestrous behaviour.

Relationships Between the First Ovulation Postpartum and Polymorphism in Genes Relating to Function of Immunity, Metabolism and Reproduction in High-producing Dairy Cows

The decrease in fertility and conception rates of high-producing dairy cows is one of the major negative impacts for today's producers. The recovery of ovarian activity postpartum is affected by the status of immunity, metabolism and reproduction and plays a critical role in subsequent fertility after parturition in the cow. In the present study we investigated the relationships between polymorphisms in genes relating to the above functions and the first postpartum ovulation as a marker of the recovery of ovarian function in the cow. In immune function related-factors, the occurrence of first postpartum ovulation within 3 weeks in the C/C genotypes of tumor necrosis factor α (TNFα) exon (55.4%) and the A/G genotypes of TNFα promoter (55.4%) was significantly higher than that in T/T genotypes of TNFα exon (14.3%) and A/A genotypes of TNFα promoter (14.3%). Moreover, anovulatory cows with the T/T genotype of TNFα exon and the A/A genotype of TNFα promoter tended to have a prolonged days open compared with those of the other genotypes of TNFα polymorphisms. In metabolic function-related factors, ovulatory and anovulatory cows had a different distribution for alleles of the growth hormone receptor, but there were no significant differences in genotype and allele frequency of insulin-like growth factor-I polymorphism. No significant relationships were found between ovarian function after parturition and polymorphisms for reproduction-related genes. In conclusion, polymorphisms of TNFα gene both in exon and promoter regions have a strong association with the early first ovulation within 3 weeks after parturition in the high-producing dairy cow. Taken together, polymorphisms of TNFα gene could be strongly related to early first ovulation after parturition, thus being an effective tool of selection for improving reproductive performance in the high-producing dairy cow.

Does supplementing dairy cows with β-carotene during the dry period affect postpartum ovarian activity, progesterone, and cervical and uterine involution?

β-carotene is the main natural precursor of vitamin A and plays an important role in reproductive efficiency and immune function in dairy cows. The objective of this study was to investigate whether a supplement of β-carotene given during the dry period is able to 1) increase blood concentrations of β-carotene postpartum, 2) improve ovarian function and progesterone production, and 3) enhance uterine involution and uterine health. This study was conducted using 40 Holstein cows. On the day of drying-off, cows were allocated to one of two dietary treatments: control diet (C, n = 20) or control diet plus 1g/d β-carotene (BC, n = 20). The β-carotene supplement was given individually to the cows until calving. Blood samples were obtained regularly before and after calving from the cows to measure the concentrations of β-carotene. The diameters of the cervix and uterine horns were measured regularly using ultrasonography. Endometrial cytology samples were acquired from the cervix and uterus to determine uterine health. Milk samples were obtained three times per week for progesterone assay. Additional blood samples were taken on the day of calving, 7 and 21 days postpartum to determine the plasma concentrations of amino acids. Blood concentrations of β-carotene were not different before the start of the experiment (C, 3.03 ± 0.22 mg/L vs BC, 3.12 ± 0.22 mg/L, P > 0.05). Blood concentrations of β-carotene in the BC group peaked (7.45 ± 0.24 mg/L) 1 month after drying-off while the concentrations in the C group remained constant. β-carotene concentrations then decreased in both groups. The difference in blood concentrations of β-carotene between groups became significant 2 weeks after the start of the supplement until 2 weeks postpartum. There was no significant difference in the interval from calving to ovulation between groups (C, 27.8 ± 3.46 d vs BC, 35.8 ± 3.55 d, P > 0.05). The dietary supplement of β-carotene during the dry period had no effect on ovarian activity, progesterone production, cervix and uterine horn diameters. Plasma concentrations of hydroxyproline in the BC group were higher than in the C group on day 21 postpartum (BC, 20.8 ± 1.33 μmol/L vs C, 15.0 ± 1.33 μmol/L; P < 0.01). On day 28 postpartum the percentage of neutrophils in the BC group was lower than in the C group (cervical smear; C, 21.0 ± 3.22% vs BC, 9.7 ± 3.14%, P < 0.05 and uterine smear; C, 32.0 ± 3.86% vs BC, 20.9 ± 3.76%, P < 0.05). In the present experiment a dietary supplement of β-carotene had no effect on ovarian activity. However, due to effects of β-carotene on hydroxyproline profiles and their potential relationship with uterine function we speculate that uterine involution may have been more complete and that uterine inflammation may have been reduced in cows which received the β-carotene compared to controls.

Serum progesterone as an indicator of cyclic activity in post-partum goat does

The aim of this trial was to assess post-partum ovarian activity of the does of two South African goat breeds from their serum progesterone concentrations. Between seven and 100 days post-partum, does from the Boer goat breed and an indigenous rural goat type were allocated to two nutritional treatments within breed. One group per breed received a concentrated diet in an intensive feeding programme. The other group per breed was subjected to a low level of nutrition through the grazing of the natural pasture in an extensive (veld) grazing system. Blood samples were collected weekly from five does per breed per treatment. Serum progesterone concentrations were determined using a Gamma Coat TM [128] progesterone radioimmunoassay kit (Sorin Diagnostics, France). Large variations in serum progesterone concentrations were recorded within and between breeds and nutritional regimens. Irrespective of breed, in the extensive groups subjected to the low level of nutrition, mean peak serum progesterone concentrations never exceeded 0.2 ng/mL. This suggests that throughout the experimental period, ovarian activity remained low in the extensive groups. It was concluded that nutritional regimen plays a significant role in ensuring high ovarian activities. Furthermore, the higher mean serum progesterone levels in the Boer goat indicate an earlier and higher oestrous activity, compared to the indigenous does.

Delayed resumption of ovarian activity postpartum and its impact on subsequent reproductive performance in Holstein cows

Delayed resumption of ovarian activity postpartum and its impact on subsequent reproductive performance in Holstein cows

Assessment of progesterone profiles and postpartum onset of luteal activity in spring calving Hereford beef suckler cattle

BackgroundReproduction is the single greatest factor limiting beef cattle production. Previous research on beef suckler luteal activity has largely focused on the mechanisms, and duration, of postpartum anoestrus. However, the temporal pattern of luteal activity after resumption of post-partum ovarian activity, and the impact of pattern type on days open (DO) in purebred beef suckler cows, are unknown.MethodsProgesterone concentration was measured in milk samples taken thrice weekly from 120 lactations, in 87 animals, on 3 farms, over two years. Onset of luteal activity (OLA) was defined as the first day milk progesterone concentration exceeded 3 ng/ml for two successive measurements, or exceeded 5 ng/ml once. It was defined as delayed if it occurred more than 61 days postpartum. A short initial luteal phase consisted of progesterone concentrations which exceeded 3 ng/ml for fewer than 4 sequential measurements. Temporal progesterone patterns were classified as: 1) Normal cyclicity; 2) Cessation of luteal activity; 3) Prolonged luteal activity; 4) Erratic phase: failure to conform to 1, 2 or 3. Data concerning parity, previous calving interval, breeding values, calf birth and 200-d weight were obtained from the Norwegian Beef Cattle Recording System database.ResultsThe mean (SD) OLA was 41 d (20). Parity and calf birth weight were inversely correlated with OLA. Delayed OLA occurred in 14.4% of lactations. A short first luteal phase occurred in 61.5% of lactations, but this was unrelated to irregular luteal phase occurrence, pregnancy or DO. Irregular luteal phases occurred in 22% of lactations. The irregularities were: prolonged luteal phase (11%); cessation of luteal activity (5%); erratic luteal activity (6%). Early OLA was associated with prolonged luteal phases. DO was positively correlated with irregular luteal phases and negatively correlated with calf 200-d weight.ConclusionsThis study demonstrates that irregular luteal phases negatively affect reproductive performance in purebred beef suckler cattle. A moderate incidence of irregular luteal phases was seen in the study population. Whilst a positive relationship was seen between OLA and DO, unfavourable associations between early OLA and incidence of irregular luteal phases should be considered when developing breeding programmes.

Effect of supplementation with corn oil on postpartum ovarian activity, pregnancy rate, and serum concentration of progesterone and lipid metabolites in F1 (Bos taurus × Bos indicus) cows

The aim was to evaluate the effect of corn oil supplementation during postpartum anoestrus on ovarian activity, pregnancy rate, progesterone (P(4)), and lipid metabolites (cholesterol, CHO; low and high density lipoproteins; LDL and HDL, respectively) concentrations in blood of F(1) (Bos taurus x Bos indicus) grazing cows. Cows were randomly assigned to an experimental group, fed with a supplement containing 4% corn oil on dry matter basis (OG, n = 11), and a control group with the same supplement without corn oil (CG, n = 12). Both supplements contained equivalent amounts of crude protein and metabolizable energy and were fed for 34 days continuously. All cows were induced to estrous 12 days after beginning of supplementation by using a synthetic progestagen and artificially inseminated 56 h after retiring the implants. Pregnancy diagnosis was performed by transrectal palpation 45 days after insemination, evaluating simultaneously ovarian activity. P(4) and lipid metabolites (CHO, HDL, LDL) concentrations were determined in blood samples collected at 3-day intervals, from the beginning of corn oil supplementation and up to 10 days after artificial insemination. Ovarian activity was affected by treatment (p < 0.05), finding ovarian structures in 72.7% of OG cows and in 50% of CG cows. Concentration of P(4) and CHO was higher for OG with respect to CG (2.52 +/- 0.65 vs 1.88 +/- 0.62 ng/ml and 117.79 +/- 11.57 vs 85.71 +/- 12.11 mg/dl, respectively), whereas pregnancy rate and blood concentrations of HDL and LDL were not affected by treatment (p > 0.05). Addition of corn oil to the supplement stimulated ovarian activity and increased serum concentrations of progesterone and cholesterol in grazing B. taurus x B. indicus cows with low body condition score showing postpartum anoestrus.

Factors affecting the incidence of postpartum oestrus, ovarian activity and reproductive performance in Thoroughbred mares bred at foal heat under Indian subtropical conditions

Decreased reproductive performance due to summer stress is a well known phenomenon in farm livestock. Whether this occurs in the mare and specifically how this might affect postpartum reproductive activity and performance, especially at Foal Heat (FH), is unknown. This study, therefore, aims to investigate this and the factors that might affect postpartum reproductive activity. Reproductive records of 228 Thoroughbred mares (694 mare years) bred in subtropical north-western India were retrospectively analysed. Overt oestrous activity occurred within 21 d postpartum in 92.94% (645/694) of mares. Significantly (p<0.001) more April foaling mares (97.37%, 185/190) expressed postpartum oestrous activity than those foaling in January (83.61%; 51/61) and February (88.49; 123/139). Similarly significantly (p<0.01) fewer multiparous mares failed to demonstrate oestrous activity than primiparous mares (6.12% vs.15.07%; 38/621 vs. 11/73, respectively). 190 of these 694 mares were additionally monitored to confirm ovulation; in these mares onset of FH (oestrus plus confirmed ovulation) occurred 8.42+/-0.17 d and first ovulation 13.64+/-0.20 d postpartum. Month, stud farm, year, and parity did not affect interval from parturition to FH onset or to first ovulation; or FH onset to ovulation. In FH bred mares Day 16 pregnancy rate and overall foaling rate were 53.76% (100/186) and 46.24% (86/186) respectively and were similar to those of mares bred later postpartum. FH pregnancy rates were not affected by stud, season, month, year, number of matings, or day of ovulation but were significantly (p<0.008) lowered by increasing mare age. Significantly (p<0.01) lower Day 16 pregnancy rates were observed in uterine treated mares compared to untreated mares (31.09% vs. 57.96%; 9/29 vs. 91/157, respectively), this difference was not evident during the rest of pregnancy. In conclusion, postpartum reproductive and ovarian activity appears to be affected by environment, i.e., delayed in subtropical kept Thoroughbred mares compared to those kept in temperate climates. However, resulting reproductive performance at FH and the factors affecting postpartum reproductive activity are similar.

Effects of first postpartum progesterone rise, metabolites, milk yield, and body condition score on the subsequent ovarian activity and fertility in lactating Holstein dairy cows

Seventy multiparous healthy lactating Holstein cows (fat-corrected milk yield = 7,561.8 kg) were monitored from 14 days before to 70 days after calving. Transrectal ultrasound scanning was performed twice weekly from 7 to 65 days postpartum. Blood samples were also collected twice weekly to measure serum P(4) and biweekly to detect serum beta-hydroxybutyrate (betaHB) and nonesterified fatty acid (NEFA) concentrations. Body condition score (BCS) was taken biweekly after calving. Based on the serum P(4) profile of 59 cows (11 cows were excluded due to the occurrence of postpartum diseases) studied, 27 (45.8%) had normal ovarian activity, while 21 (35.6%), six (10.1%), three (5.1%), and two (3.4%) had delayed ovulation (DOV), prolonged luteal phase (PLP), short luteal phase (SLP), and cessation of ovarian activity, respectively. Cows with PLP had an earlier ovulation compared to that of cows with normal ovarian activity (23.16 +/- 4.02 vs 31.9 +/- 8.35 days; P < 0.05). PLP cows also had a greater mean +/- standard deviation peak milk yield (44.2 +/- 5.8 vs 37.2 +/- 5.7 kg/day, 75 days postpartum; P < 0.05) than cows with normal postpartum ovarian activity. The PLP group also had greater milk production in the previous lactation period. Logistic regression analysis indicated that cows with P(4) concentration > or =1 ng/ml on day 24 after calving were more at risk for PLP by 1.1 for each 1 kg increase in mean peak milk yield during 75 days after calving. BCS was lower in cows with DOV compared to that of cows with normal ovarian activity at any time after calving (P < 0.05). Serum betaHB concentrations in DOV cows were significantly higher than that of normal cows on day 42 after calving (0.69 +/- 0.29 vs 0.54 +/- 0.12 mmol/L, P < 0.05). No significant difference was found in the mean concentrations of NEFA between cows in different groups at any time after calving (P > 0.05). The concentrations of P(4) on days 28 and 31 were negatively correlated with betaHB concentration on day 42 after calving in cows with normal ovarian activity (R = -0.44, P = 0.02). In conclusion, these findings suggest that early ovulation and hence early postpartum P(4) rise in addition to the high milk production could partly be responsible for the occurrence of PLP in dairy cows.

Supplementation of Barbarine ewes with spineless cactus ( Opuntia ficus-indica f. inermis) cladodes during late gestation-early suckling: Effects on mammary secretions, blood metabolites, lamb growth and postpartum ovarian activity

This trial investigated effects of cactus incorporation in the diet of the late pregnant-early suckling ewe on mammary gland secretions, blood metabolites, ovarian activity and lamb growth. Thirty-four single bearing ewes of the Barbarine breed aged 4.4 ± 1.7 years that were oestrus synchronised were selected. Animals were allocated to either barley treatment ( n = 17) with daily feeding of 1.5 kg of oaten hay, 0.33 kg of barley and 0.11 kg of soybean meal per ewe or to a cactus treatment ( n = 17), with feeding of 1.5 kg of oaten hay, 3 kg of cactus cladodes and 0.14 kg of soybean meal per ewe. The trial lasted approximately 60 days and started 4 weeks before lambing and continued until 30 days postpartum. Plasma concentrations of phosphorus, total protein, glucose and insulin before and after lambing slightly differed between ewes in both treatment groups and were more affected by time relative to lambing. Ewes fed cactus had higher ( P < 0.05) plasma levels of calcium than their counterparts fed barley. Colostrum production did not differ between feeding regimes. The colostrum immunoglobulin G concentrations averaged 160 and 149 g/l (S.E.M. = 12.9) in the barley and cactus groups, respectively. Milk yield at day 10 and 30 from birth was not affected by treatment ( P > 0.05). Milk yield at 30 days was 1030 and 1041 g/day (S.E.M. = 96.9) for barley and cactus, respectively. Lamb live weight at 10 days of age was, respectively, 6.2 and 6.8 kg (S.E.M. = 0.23) for barley and cactus and identical (9.5 kg) at 30 days of age. The feeding regime did not affect ovarian activity at 30 days from lambing. It is concluded that cactus can totally replace barley grain in the diet of late pregnant-early suckling Barbarine ewes without affecting mammary secretions, resumption of ovarian activity or lamb growth.

Effect of Restricted Suckling on Body Weight, Body Condition Score and Onset of Postpartum Ovarian Activity in F1 Cows under Tropical Conditions

Effect of Restricted Suckling on Body Weight, Body Condition Score and Onset of Postpartum Ovarian Activity in F1 Cows under Tropical Conditions

Postpartum ovarian activity and uterine involution in non-seasonal Shiba goats, with or without nursing

Postpartum ovarian activity, uterine involution, and the relationship with hormonal profiles were studied in non-seasonal Shiba goats, with or without nursing of their kids. After parturition, does were allocated to one of two groups, with either weaning on the day of parturition ( n = 3; non-nursing group) or weaning at 7–10 weeks after parturition ( n = 4; nursing group). Blood sampling (starting 7 days prior to expected day of parturition) and transrectal ultrasound evaluations (starting 2 days after parturition) were conducted every other day or daily to monitor the follicular dynamics, uterus size, and the levels of plasma progesterone, blood glucose, and insulin concentration until at 3 weeks following the first postpartum ovulation. In the nursing group, blood samples were also collected every 10 min for an 8 h period on the day before weaning, 2 and 6 days after weaning, for the analysis of the pulsatile patterns of LH release. In all animals, the blood glucose concentrations increased transiently on the day before parturition and were significantly ( p < 0.05) higher than those on the day of parturition (mean of 144 ± 48.8 mg/dl vs 63 ± 11.2 mg/dl). In the non-nursing group, the first postpartum ovulation was observed 9.3 ± 3.2 days after parturition, while in the nursing group, no ovulation occurred before weaning in any of the goats. Here ovulation was observed 18.8 ± 5.0 days after weaning, which was significantly ( p < 0.05) later than in the non-nursing group. After first ovulation, all animals in both groups showed early luteal regression. No significant difference in the time required for the completion of uterine involution was recorded between the non-nursing and nursing groups (18.3 ± 4.2 days vs 19.3 ± 3.6 days, respectively), nor in the plasma LH pulse frequency obtained before (1.3 ± 0.5 pulses/8 h), 2 (1.3 ± 1.0 pulses/8 h) and 6 days (2.0 ± 0.8 pulses/8 h) after parturition, in the nursing group. It can be concluded that no ovulation occurs during nursing postpartum, suggesting that nursing is a determinant of the resumption of ovulation in these non-seasonal goats. Ultrasonic observations of the ovary suggest that uterine involution was not influenced by nursing or suckling.

Defining delayed resumption of ovarian activity postpartum and its impact on subsequent reproductive performance in Holstein cows

The objectives of this study were to derive a useful case definition of delayed resumption of ovarian activity, based on factors associated with reduced fertility, and to assess its impact on subsequent reproductive performance in Holstein cows ( Bos taurus). Milk samples were collected twice weekly from 219 cows from four commercial herds, and whole-milk progesterone concentrations were determined with an enzyme-linked immunosorbent assay. Ovulation was considered to have occurred 5 d before the first rise of milk progesterone concentration above the basal level. Survival analysis was used to derive a case definition of delayed resumption of ovarian activity postpartum based on factors that were predictive of reduced pregnancy rate. First postpartum ovulation occurring beyond 35 d postpartum was associated with a reduced pregnancy rate (hazard ratio [HR] = 0.50; P < 0.001) and was defined as delayed resumption of ovarian activity; overall, 75 (34.9%) cows were in this category. These cows were more likely not to conceive on first artificial insemination (odds ratio [OR] = 2.85; P = 0.01) and more likely not to become pregnant within 100 d (OR = 3.30; P = 0.001) and 210 d (OR = 3.20; P < 0.001) postpartum compared with cows with normal resumption of ovarian activity. Furthermore, 13 (6%) cows that ovulated within 35 d postpartum had a prolonged (≥14 d) interval between either first and second or second and third luteal phases postpartum. A prolonged interluteal interval was also associated with a reduced pregnancy rate (HR = 0.35; P = 0.02). Days open (mean ± SEM) were greater (P = 0.0002) in cows with delayed resumption of ovarian activity (213 ± 13 d) and in cows with prolonged interluteal interval (220 ± 37 d) than in cows with normal resumption of ovarian activity (152 ± 9 d). In conclusion, first ovulation occurring beyond 35 d postpartum was defined as delayed resumption of ovarian activity, and the first ovulation occurring within 35 d postpartum but the absence of luteal activity ≥14 d between two consecutive luteal phases was defined as a prolonged interluteal interval; both abnormalities adversely affected the subsequent reproductive performance of Holstein cows.

Postpartum ovarian activity in multiparous Holstein cows treated with bovine somatotropin and fed n-3 fatty acids in early lactation

Multiparous cows (n=59) were blocked by expected calving date and previous 305-d mature-equivalent milk yield and assigned randomly to a 2×2 factorial design to determine the effects of bovine somatotropin (bST; Posilac, Monsanto Animal Agricultural Group, St. Louis, MO) and dietary fat on ovarian activity during the first 90 d in milk (DIM). Diets that included whole, high-oil sunflower seeds [SS; 10% of dietary dry matter; rich in linoleic acid (18:2)] or a mixture of Alifet-High Energy and Alifet-Repro [AF; Alifet USA, Cincinnati, OH; 3.5 and 1.5% of dietary dry matter, respectively; protected source of linolenic (18:3), eicosapentaenoic, and docosahexaenoic fatty acids] were provided from calving. Diets were isocaloric at equal intakes, but AF provided more net energy for lactation at actual intakes (1.54 vs. 1.66 Mcal/kg of dry matter). Cows received 0 or 500mg of bST (N, Y) every 10 d from 12 to 70 DIM and at 14-d intervals from 70 to 280 DIM. Breeding was initiated after 90 DIM. Follicular dynamics, luteal growth and development (15 to 90 DIM), and plasma progesterone concentrations (1 to 90 DIM) were evaluated (3 times per week). Days to first ovulation (33.6±1.4) and incidence of anovulation at 45 or 70 DIM did not differ among treatments. Interovulatory intervals were similar among treatments (22.1±0.9 d). Incidence of estrous cycles with 2 follicular waves was greater for SSY (71.0%) and AFN (80.0%) than for other groups, but more 3-wave cycles occurred with AFY (83.3%). Growth rate of the ovulatory follicle was greater for AF than SS (1.9 vs. 2.2±0.11 mm/d) and diameter of ovulatory follicles was larger for AFN than the other treatments (17.9 vs. 15.7±0.7mm). Area under the progesterone curve was reduced for SSY (63.2, 48.1, 55.5, and 61.4±5.1 ng·d/mL for SSN, SSY, AFN, and AFY, respectively). The number of class 1 (3 to 5mm) follicles was decreased and the number of class 2 (6 to 9mm) follicles was increased by bST. The number of class 2 follicles was reduced by AF. Initiation of bST administration at 12 DIM and dietary n-3 fatty acids altered ovarian activity during the first 90 DIM and could benefit reproductive performance. Dietary n-3 fatty acids interacted with bST administration in early lactation to increase the incidence of estrous cycles with 3 follicular waves. Although these changes could benefit reproductive performance, evaluation with a larger number of cows is needed to determine if these alterations improve fertility.