Pregnancy rates after fixed-time artificial insemination of Brahman heifers treated to synchronize ovulation with low-dose intravaginal progesterone releasing devices, with or without eCG

The objective was to determine whether eCG in an ovulation synchronization protocol with an intravaginal progesterone (P₄)-releasing device (IPRD) containing a low dose of P₄ improves pregnancy rate (PR) to fixed-time AI (FTAI) in Bos indicus heifers. Day 0, 2 y old Brahman heifers were allocated to either eCG+ (n = 159) or eCG- (n = 157) treatment groups. All heifers were weighed, body condition scored (BCS), and ultrasonographically examined to measure uterine horn diameter and presence of a CL. On Day 0, all heifers received a low-dose IPRD (0.78 g P₄) and 1 mg of estradiol benzoate (EB) im. On Day 8, the IPRD was removed, all heifers received 500 μg cloprostenol im, and those in the eCG+ treatment group received 300 IU of eCG im. On Day 9, all heifers received 1 mg EB im. All heifers were FTAI 52 to 56 h after IPRD removal. Ten days after FTAI, heifers were exposed to bulls. Heifers were diagnosed as pregnant to FTAI, natural mating, or not detectably pregnant (NDP) 65 d after FTAI. Treatment with eCG+ as compared to eCG- did not affect PR to FTAI (28.9 vs 30.6%; P = 0.590), natural mating (51.3 vs 47.7%; P = 0.595), or overall (65.4 vs 63.7%; P = 0.872). Mean live weight gain from Days 0 to 65 d post-FTAI was higher in heifers pregnant to FTAI (72.29 ± 4.26 kg; P = 0.033) and overall (66.83 ± 3.65 kg; P = 0.021), compared to heifers that were NDP (60.03 ± 3.16 kg). Uterine diameter group, 9–11, 12–13, and 14–20 mm (26.2, 31.3, and 33.3%; P = 0.256), presence and absence of CL (29.8 vs 29.4%; P = 0.975), AI technicians 1, 2, and 3 (32.6, 28.8, and 22.4%; P = 0.293) and sires A, B, and C (23.9, 36.0 and 27.0%; P = 0.122) had no effect on PR to FTAI, natural mating, or overall. In conclusion, treatment of primarily cycling Brahman heifers with 300 IU eCG in conjunction with a low P₄-dose (0.78 g) IPRD and EB to synchronize ovulation, did not improve PR after FTAI, natural mating, or overall.     

Effects of kisspeptin-10 on the reproductive performance of sows in a fixed-time artificial insemination programme

Kisspeptin (KP) is a major positive regulator of the hypothalamo–pituitary–gonadal axis and affects female reproductive cyclicity in mammals. It offers an attractive alternative strategy to control reproduction in fixed-time artificial insemination (FTAI) protocols. We aimed to evaluate the effects of different doses of kisspeptin-10 (KP-10) on sow reproductive performance in FTAI protocols. One hundred ninety-eight weaned sows were divided into three groups at random. A FTAI–GnRH group of sows (n = 98) received 100 µg (2 mL) gonadotropin-releasing hormone (GnRH; gonadorelin) by intramuscular injection at 96 h after weaning (t = 0 h); FTAI–KPL (KPL: low-dose KP-10, n = 50), and FTAI–KPH groups of sows (KPH: high-dose KP-10, n = 50) received 0.5 or 1 mg KP-10 (2 mL) respectively at 96 h after weaning. Sows were checked twice daily for oestrus. Ultrasonographic evaluations were performed to determine the follicular diameter and time of ovulation; blood samples were collected immediately before injection (t₀ = 0 min) and at 15, 30, 45, 60, 75, 90 min, 24 and 48 h postinjection. Sows were inseminated at 112 and 132 h after weaning. The oestrus rates (96 vs 92%; 96 vs 88%) and weaning-to-oestrus intervals (98.9 vs 98.6 h; 98.9 vs 97.1 h) were not affected by treatment, but oestrus in the FTAI–KPL group was significantly longer than in the FTAI–GnRH group (38.7 vs 30.0 h; P < 0.05). The peak LH concentrations were 1.29 times greater than at t₀ = 0 in the FTAI–GnRH group, and 1.45 and 1.44 times greater than at t₀ = 0 in the FTAI–KPL and FTAI–KPH groups, respectively. Follicular diameters and pregnancy rates (86 vs 88%, 86 vs 80%, respectively) did not differ between the treatments. Moreover, the total numbers of piglets born and those born alive did not differ among the three groups. These findings suggested that 0.5 mg KP-10 given at 96 h after weaning could be used in FTAI programmes to manage batch farrowing in sows.     

Fixed-time artificial insemination in red deer (Cervus elaphus) in Argentina

Synchronization of estrous and fixed-time artificial insemination (FTAI) was conducted during the reproductive season of 2008 (March–April) in a local red deer breeding farm in Argentina. Multiparous suckling hinds (n = 38) were artificially inseminated following hormonal treatment (intravaginal sponge containing 100 mg of medroxiprogesterone acetate). At the time of sponge removal (day 12) 250 IU of eCG and 500 μg of PGF2α were given to each hind. The FTAI was performed at 48–55 h after device removal with cryopreserved semen imported from New Zealand. Rectal-transcervical AI method (similar to that in cattle) was performed and semen was deposited within the uterine body (n = 28) or the cervix (n = 10). Pregnancy was diagnosed by means of ultrasonography 44 days after FTAI. The overall pregnancy rate was 36.8% (14/38). Percentage of does that became pregnant with intrauterine seminal deposition was 42.9% (12/28) whereas pregnancy rate in the hinds with intracervical AI was 20% (2/10; P = 0.27).     

A comparison of the reproductive performance in primiparous sows following two timed artificial insemination protocols

Timed artificial insemination (TAI) is an efficient reproductive technology in batch farrowing production that aids management in pig farms. However, the effect of TAI on the reproduction performance is still controversial. This study aimed to evaluate the effects of two TAI protocols on the reproductive performance of primiparous sows. A total of 332 weaned sows were randomly allocated into three treatments. Sows assigned to Control (n = 110) were untreated and inseminated on each day in oestrus after weaning. Sows assigned to eG-TAI (n = 112) received equine chorionic gonadotropin (eCG) 24 h after weaning and gonadotropin-releasing hormone (Gonadorelin: GnRH) at oestrus, and were inseminated at 8 and 32 h later if oestrus at 0800, or 16 and 40 h later if oestrus at 1600. Sows assigned to 2e-TAI (n = 110) received eCG and GnRH 24 h and 96 h after weaning, respectively, and were inseminated 16 and 40 h after GnRH administration. Sows showing oestrus at GnRH administration or 64 h after were inseminated immediately, for a total of three inseminations. Ultrasonographic evaluations were performed to determine the follicular diameter and time of ovulation. Most sows in the 2e-TAI and eG-TAI groups ovulated 0–48 h after the GnRH injection. Our results indicated that oestrus rate within seven days after weaning in the experimental groups was higher, and weaning-to-oestrus interval was shorter than in the control group (99.3 h vs 113.5 h, P < 0.05). The breeding and farrowing rates in the experimental groups were significantly higher than in the control group (P < 0.05), while the numbers of total born, live-born and stillborn were not different among the three groups (Control: 12.7, 11.6 and 1.1; 2e-TAI: 12.4, 11.3 and 1.0; eG-TAI: 12.0, 11.4 and 0.4, respectively). These results indicated that TAI could ensure a high farrowing rate in primiparous sows under batch farrowing management.     

The effect of GnRH,eCG and progestin type on estrous synchronization following laparoscopic AI in ewes

The aim of the experiment was to evaluate the effects of GnRH and/or eCG and progestin type (implant versus CIDR) on the induction of estrus and pregnancy rate following laparoscopic AI (LAI) with frozen semen. In the first trial, ewes (n = 129) were treated with norgestomet implants for 14 days. At implant removal ewes received eCG (400 IU) and/or GnRH (25 μg) 36 h after removal, resulting in control, eCG, GnRH, and eCG/GnRH groups (n = 30–34/group). In trial 2, ewes (n = 36) were treated with intravaginal fluorogestone acetate sponges (FGA) or CIDR for 12 days. After withdrawal, half of the ewes from each progestin group received eCG (400 IU), resulting in sponge, sponge/eCG, CIDR and CIDR/eCG groups (n = 8–10/group). In both trials, estrous activity was assessed using a vasectomized ram from the time of progestin removal to laparoscopic AI with frozen semen 58–60 h (trial 1) or 54–56 h (trial 2) following cessation of treatment. In trial 1, GnRH decreased (P < 0.05) the percentage of ewes in estrus (GnRH, 75.8% versus control, 93.8% versus eCG/GnRH, 94.1%), however pregnancy rates were similar in all groups (control, 53.1%; eCG, 70.0%; GnRH, 51.5%; eCG/GnRH, 55.9%, respectively). In trial 2, neither the type of progestin nor eCG treatment effected the percentage of ewes in estrus (sponge, 75.0%; sponge/eCG, 100.0%; CIDR, 100.0%; CIDR/eCG, 90.0%). However, pregnancy rates following LAI were higher (P < 0.05) when ewes were treated with eCG (progestin + eCG, 73.7% versus progestin alone, 41.2%). Results demonstrate that the source of progestin does not influence the expression of estrus or the proportion of ewes pregnant following LAI. When progestin treatment protocols are used in combination with eCG, pregnancy rates can be increased. A dose of GnRH near the end of progestin treatment may decrease the estrous response, by inducing ovulation before normal expression of estrus.     

Heat stress of gilts around farrowing causes oxygen insufficiency in the umbilical cord and reduces piglet survival

Late gestating sows are susceptible to high ambient temperatures, possibly causing farrowing complications and reducing piglet survival. This experiment aimed to quantify in the days leading up to farrowing the impact of sow heat stress (HS) on farrowing physiology and survival of the piglets. Pregnant primiparous sows (gilts) were allocated to either thermoneutral control (CON, n = 8; constant 20 °C) or cyclical HS conditions (n = 8; 0900 h to 1700 h, 30 °C; 1700 h to 0900 h, 28 °C) from d 110 of gestation until farrowing completion. Gilt respiration rate, skin temperature and rectal temperature were recorded daily, and farrowing duration was quantified by video analyses. Blood samples were collected from the piglet umbilical vein at birth. At 48 h of age, piglet growth was quantified by morphometric analyses. The thermal exposure model induced HS and respiratory alkalosis in the gilts, as indicated by increased respiration rate, rectal temperature, skin temperature (all P < 0.001), plasma cortisol (P = 0.01) and blood pH (P < 0.001). Heat-stressed gilts took longer to start expelling placentae (P = 0.003), although the active farrowing duration was not significantly different between treatments. Stillbirth rates were higher in the HS group (P < 0.001), with surviving piglets at birth having lower umbilical vein partial pressure of oxygen (P = 0.04), oxygen saturation rate (P = 0.03) and tending to have increased lactate concentrations (P = 0.07). At birth, piglet skin meconium staining scores were greater in the HS group (P = 0.022). At 48 h of age, piglets from the HS group had reduced small intestinal length (P = 0.02), reduced jejunal crypt depth (P = 0.02) and lighter absolute brain weight (P = 0.001). In contrast, piglet BW, growth rate, relative organ weight and small intestinal mucosal barrier function did not change between treatments. Collectively, these findings demonstrated gilt HS during late gestation caused farrowing complications and reduced the umbilical oxygen supply to the piglets at parturition, leading to increased risks of piglet stillbirth with implications on impaired neonatal survivability and development.     

Effects of fixed-time artificial insemination using triptorelin on the reproductive performance of pigs: a meta-analysis

Triptorelin (TRI), a gonadotropin-releasing hormone agonist allowing ovulation synchronization in pigs, is indispensable for fixed-time artificial insemination (FTAI) protocols. However, the effect of FTAI using TRI (FTAI-TRI) on the reproductive performance is controversial. We performed a meta-analysis to determine whether FTAI-TRI affects reproductive performance of pigs, including pregnancy rate (PR), number of pigs born alive per litter (NBA), farrowing rate (FR) and total number of pigs born per litter (TNB). A total of 37 trials from 15 studies were extracted and analysed in Stata. A weighted mean difference (WMD) with 95% confidence interval (CI) was calculated for NBA and TNB, and risk ratio (RR) with 95% CI was calculated for PR and FR. Pregnancy rate, TNB and NBA data were applied to a fixed-effect protocol, and FR data were applied to a random-effect protocol. We found that for weaned sows, the FTAI-TRI group had comparable reproductive performance to the artificial insemination (AI) following oestrus detection (EDAI) group. Fixed-time AI has many advantages, including the elimination of the need to heat-check twice daily, so that FTAI-TRI is a good substitute for EDAI. Subgroup analysis indicated that the optimal timing of triptorelin treatment was 96 h after weaning, which gave significant positive effects on PR (RR = 1.08, P = 0.000) and non-significant positive effects on TNB (WMD = 0.12, P = 0.452). Triptorelin at a dose of 100 μg showed better effects than 200 μg, with significant positive effects on PR (RR = 1.09, P = 0.005) and FR (RR = 1.06, P = 0.036). So a single dose of 100 μg was recommended. The optimal protocol was insemination at 24 h and again at 48 h after triptorelin administration if they remained in standing oestrus, and this provided a significantly higher NBA (WMD = 0.59, P = 0.013) that increased by 0.59. For gilts, the FTAI-TRI group showed decreased (not significant) PR (RR = 0.96, P = 0.127) and significantly decreased FR (RR = 0.93, P = 0.013), TNB (WMD = −0.85, P = 0.006) and NBA (WMD = −0.98, P = 0.000), which were inferior to those in the EDAI group. In conclusion, the effects of FTAI-TRI on the reproductive performance of pigs were parity-, treatment timing-, insemination timing-, and dosage-dependent. Fixed-time AI using triptorelin could effectively replace the EDAI protocol for sows, but not for gilts.     

The effect of equine chorionic gonadotropin (eCG) on pregnancy rates of white-tailed deer following fixed-timed artificial insemination

Control of the white-tailed doe's reproductive cycle is not well documented. The objective was to determine the effects of giving equine chorionic gonadotropin (eCG) at progesterone device removal on fixed time artificial insemination (FTAI) pregnancy rates in white-tailed does. All does (n = 74) were synchronized with a vaginal progesterone implant (CIDR; 0.3 g progesterone), inserted on Day 0 (without regard to stage of estrous cycle), removed 14 days later, and subjected to FTAI, on average, 60 h post-CIDR removal. Of these, 34 were given 200 IU (im) of eCG at CIDR removal. Overall, FTAI pregnancy rate was 50% across 2 yrs (effect of year, P = 0.35). Administration of eCG at CIDR removal did not affect (P = 0.16) pregnancy rate (eCG = 59%; no eCG = 43%). Pregnancy rates were not affected by vulva score or doe disposition. Does that were ≤ 4 yrs old were more likely (P = 0.01) to become pregnant than does > 4 yrs of age. Does inseminated ≥ 60.5 h after CIDR removal were 22 times more likely (P = 0.002) to become pregnant to FTAI than does inseminated < 60.5 h. When frozen-thawed semen was deposited in the cervix or uterus, does were 17 times more likely (P = 0.005) to become pregnant compared with those receiving intravaginal insemination. Fecundity was not different (P = 0.73) across treatment groups (1.6 ± 0.11; no eCG vs. 1.7 ± 0.10; eCG). Furthermore, fecundity of does pregnant to FTAI was not different (P = 0.72) compared with does pregnant to clean-up bucks (1.7 ± 0.08; AI does vs. 1.7 ± 0.09; clean-up bucks). In summary, white-tailed does were successfully inseminated using a 14 days FTAI protocol, eCG may not be essential for acceptable pregnancy rates, and increased pregnancy rates may result when FTAI is done ≥ 60.5 h after progesterone device removal.     

Effects of oestrous synchronization with altrenogest in gilts on endometrial and embryonic characteristics

The use of altrenogest (ALT) supplementation for oestrous synchronization improves subsequent reproductive performance of gilts and sows. However, the causes of this improvement in reproductive performance after ALT treatment are not fully/clearly understood. The objective of this study was to evaluate the effects of ALT supplementation for oestrous synchronization in gilts on the endometrial glands and embryonic development characteristics at 28 days of pregnancy. Pregnant gilts were divided into two experimental treatments: Control (did not receive ALT; n = 9 gilts) and ALT (ALT feeding at 20 mg/day for 18 days; n = 9 gilts). At 28 days of pregnancy, six gilts from each treatment were slaughtered, and reproductive tracts were immediately evaluated. There was no statistical difference (P > 0.05) between treatments regarding ovulation rate, number of embryos, number of vital embryos and number of non-vital embryos. Embryo weight, length and embryonic vesicle weight were lower in ALT treatment compared with Control (P < 0.01), and it was lower in the cervical uterine region compared with apex uterine region, respectively (P < 0.05). Higher values of gland duct area, gland duct perimeter, percentage of the glandular area and total endometrial area were observed in ALT treatment compared with Control (P < 0.05). The use of ALT during 18 days for oestrous synchronization in gilts increased the gland duct area, perimeter and total endometrial area but did not increase the embryo number and embryo size at day 28 of pregnancy.     

Effects of increasing standardized ileal digestible lysine during gestation on reproductive performance of gilts and sows

Limited information is available on lysine requirement estimates of modern, high-producing gestating sows Therefore, the objective of this study was to evaluate the effects of increasing standardized ileal digestible (SID) lysine during gestation on piglet birthweight and reproductive performance of gilts and sows. A total of 936 females (498 gilts, 438 sows; Camborough®, PIC, Hendersonville, TN) were group-housed (approximately 275 females per pen) and individually fed with electronic sow feeders. Females were moved from the breeding stall to pens on d 4 of gestation and allotted to one of four dietary treatments on d 5. Dietary treatments included increasing SID lysine intake (11.0, 13.5, 16.0, and 18.5 g/d). Gilts (parity 1) and sows (parity 2+) received 2.1 and 2.3 kg (22.2 and 24.3 MJ net energy per day) of feed throughout the entire gestation period, respectively. Dietary treatments were achieved by different blends of low (0.48% SID lysine) and high (0.88% SID lysine) lysine diets, prepared by changing the amount of corn and soybean meal in these two diets. Female weight and backfat were recorded on d 4 and 111 of gestation. Individual piglet weight was obtained within 12 h of birth on litters from 895 females. Final weight, and calculated maternal BW, body lipid, and body lean at d 111 of gestation increased (linear, P < 0.01) for gilts and sows as SID lysine increased. There was no evidence for differences in final backfat depth. Average total born for gilts and sows was 15.3 and 16.0 pigs with no evidence for differences among treatments. The percentage of pigs born alive increased (P = 0.01) with increasing SID lysine intake for sows, but not in gilts as a result of a treatment by parity group interaction (P = 0.04) for percentage of stillborn pigs. Increasing SID lysine intake during gestation did not affect the percentage of mummified fetuses, total born, or birthweight of piglets born alive in this study. In addition, increasing SID lysine intake during gestation did not affect subsequent reproductive performance. In conclusion, increasing dietary SID lysine intake in gestation increased female BW, without changing backfat depth. The minimal effects on female reproductive performance and piglet birthweight suggest that 11 g/day of SID lysine intake appears to be adequate for gestating gilts and sows; however, providing sows with 18.5 g/d SID lysine reduced (P = 0.01) stillbirth rate by 2.3 percentage points.     

Influence of different reproductive rhythms on serum estradiol and testosterone levels,features of follicular population and atresia rate,and oocyte maturation in controlled suckling rabbits

The aim of the current work was to analyze the features of ovarian follicular population and their quality in New Zealand white rabbit does synchronized by 24-h controlled doe-litter separation before artificial insemination (AI) during all their reproductive cycles. Synchronized animals were allocated systematically in two groups. A total of 73 rabbit does (group A) were submitted to a 35-day intensive rhythm (AI on day 4 post-partum [pp] and weaning at 25 days of lactation), and 108 rabbit does (group B) were submitted to a 42-day semi-intensive rhythm (AI on day 11 pp and weaning at 35 days of lactation) during 9 months. At the mid-end of their reproductive life, a total of 26 does (5.4 parturitions), under intensive (n = 15) or semi-intensive rhythm (n = 11) were either treated in each group with 25 IU eCG 48 h before laparotomy to recover their ovaries (n = 7 for group A and n = 6 for group B) (according to the Bioethics Committee of the University) or not synchronized with the hormonal treatment (n = 8 for group A and n = 5 for group B). Blood samples were collected at the moment of ovary recovery; morphometrical parameters, number of total follicles and number of follicles ≥1 mm in size in the ovarian surface were recorded. Oocytes from follicles of one ovary were recovered and matured in TCM 199 supplemented with 10 ng/ml EGF, 100 ng/ml IGF-I and 10% FCS. The counterpart ovaries were fixed in paraformaldehyde solution for histological studies. Detection of cell apoptosis was determined using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labelling (TUNEL) technique. Reproductive performance was affected by the rhythm used, with lower reproductive parameters in the intensive group. The average ovary height and width, the mean number of ≥1 mm follicles and the number of total follicles were similar between groups. Serum concentrations of estradiol (E₂) and testosterone (T) were significantly lower in group A vs. B (E₂: 232.4 ± 56.1 vs. 399.7 ± 53.0 pg/ml; P < 0.05 and T: 1.07 ± 0.10 vs. 1.68 ± 0.23 ng/ml; P < 0.05). No significant differences were found in follicular population or in the mean follicular apoptosis index between groups. Metaphase II rate was significantly lower in group A vs. B (48.5 ± 3.3 vs. 67.6 ± 3.7%; P < 0.01), as well as the migration rate of cortical granules (12.7 ± 2.7 vs. 38.2 ± 6.6%; P < 0.001). On the other hand, neither follicular population, nuclear maturation rate nor apoptosis rate were affected by the eCG treatment, but cytoplasmic maturation was higher in animals treated with eCG in group A (29.2% vs. 5.5%; P < 0.01). In conclusion, rabbit does under transient litter separation during their reproductive life have both their serum estradiol and testosterone concentrations and oocyte quality influenced by the intensive rhythm, leading to a decrease in reproductive parameters. Also, both intensive and semi-intensive rhythms seem to be less receptive to eCG treatment than expected.     

Effects of sodium butyrate supplementation on reproductive performance and colostrum composition in gilts

Nutrients are essential for the health and survival of human beings and animals. Also, they play a major role in enhancing reproductive efficiency. The aim of the current study was to investigate the effects of sodium butyrate (SB) on reproductive performance and colostrum composition in gilts. A total of 40 Large White×Landrace replacement gilts (at the age of 160 to 175 days) were fed either a standard diet (control group, n=20) or standard diet top dressed with encapsulated SB at the level of 500 mg/kg (SB group, n=20) from 1 month before mating to 7 days after farrowing. The rate of gilts regular return to estrus after insemination was lower in SB group than the control group. The total number of piglets born (P=0.179) and the litter weight at birth (P=0.063) did not differ between the two treatment groups. However, the mean BW at day 7 tended to be greater in SB group (P=0.051) and average daily gain of piglets was greater (P=0.011) compared with control group. Colostrum samples were collected at parturition and the concentrations of total protein (P=0.197), cholesterol (P=0.161) and lactose (P=0.923) were not influenced by SB supplementation. However, compared with control gilts, colostrum from SB-treated gilts contained lower triglyceride (P=0.050). Moreover, colostrum concentrations of prolactin (P=0.005) and leptin (P=0.006) were significantly lower in SB group. No significant differences were noted for the colostral concentrations of cortisol (P=0.899), thyroxine (P=0.891) or triiodothyronine (P=0.194). The concentration of lipopolysaccharide in colostrum was not influenced by SB supplementation (P=0.972). However, colostrum from SB-treated gilts had significantly lower tumor necrosis factor α (TNFα) (P=0.030) and higher immunoglobulin A (IgA) (P=0.042). Collectively, SB supplementation could reduce the rate of gilts return to estrus, alter the composition of colostrum and enhance the growth rate of piglets. Moreover, SB could alter the immune function of newborn piglets through decreased production of TNFα and increased IgA concentration in colostrum.     

The effect of addition of equine chorionic gonadotropin to a progesterone-based estrous synchronization protocol in buffaloes (Bubalus bubalis) under tropical conditions

Poor estrus expression and anestrus decrease the reproductive efficiency of buffaloes. The objective of this study was to determine whether the addition of equine chorionic gonadotropin (eCG) to an estrous synchronization protocol and timed insemination could improve ovulation and pregnancy rates of anestrous buffalo cows under tropical conditions. The study population comprised 65 lactating Murrah buffalo cows which were assigned to CIDR (n = 33) or CIDR + eCG (n = 32) treatment groups. Cows in the CIDR group were fitted for 8 d with a controlled intravaginal drug release (CIDR) device containing 1.38 g progesterone, received GnRH (10 μg i.m.) on D 0, PGF_2α (750 μg i.m.) on D 7, and GnRH (10 μg i.m.) on D 9; whereas cows in the CIDR + eCG group received the same treatment plus eCG (500 IU, i.m.) at the time of PGF_2α treatment. All cows were inseminated 16-20 h after the second GnRH treatment. Blood samples were obtained 10 d before the start of synchronization treatment (Day -10) and at the onset of treatment (Day 0). Cows with plasma progesterone concentrations <1 ng/mL recorded in both samples (Low-Low levels of P4) were classified as non-cyclic cows. Similarly, when either one or both of the sample pair contained concentrations of serum progesterone ≥1 ng/mL (High-High, Low-High, or High-Low levels of P4), the buffaloes were classified as cyclic cows. Ovulation rate, defined as the number of buffaloes with at least one corpus luteum 10 days after insemination, was significantly higher (P = 0.018) in the CIDR + eCG (84.4%) cows than in the CIDR cows (57.6%). Pregnancy rate was numerically lower in CIDR (27.3%) than CIDR + eCG (40.6%) cows, though differences were not significant (P = 0.25). Pregnancy rates for CIDR + eCG cows were similar to that of cows inseminated after natural estrus (40.9%; 29/71). In the non-cyclic animals, higher ovulation rates (P = 0.026) were recorded for the CIDR + eCG (81%) than for the CIDR cows (47.4%). Our results indicate that the addition of eCG to a progesterone-based estrous synchronization regimen substantially improves the ovulation rate in non-cyclic buffaloes. When this treatment is followed by timed AI, pregnancy rates achieved in anestrous buffaloes, whether cyclic and non-cyclic, may approach the rates observed in cows inseminated at natural estrus.     

Estrous expression during a fixed-time artificial insemination protocol enhances development and interferon-tau messenger RNA expression in conceptuses from Bos indicus beef cows

Expression of estrus (EST) near the time of fixed-time artificial insemination (FTAI) increases pregnancy success in beef females. This outcome has been associated with improved pregnancy establishment and maintenance, although research is still warranted to validate this theory. Hence, this experiment compared ovarian, uterine and conceptus factors associated with pregnancy establishment in Bos indicus beef cows according to estrous expression during a FTAI protocol. One hundred lactating multiparous Nelore cows received a 2 mg injection of estradiol benzoate and an intravaginal progesterone (P4) releasing device on day −11, a 12.5 mg injection of prostaglandin F_2α on day −4, P4 device removal in addition to 0.6 mg injection of estradiol cypionate and 300 IU injection of equine chorionic gonadotropin on day −2, and FTAI on day 0. An estrous detection patch was attached to the tailhead of each cow on day −2, and estrous expression was defined as removal of >50% of the rub-off coating from the patch at FTAI. Overall, 39 cows expressed EST, 55 did not express EST (NOEST), and six cows lost their patch and were discarded from the experiment. Ovarian ultrasonography was performed at FTAI, and on days 7 and 15 of the experiment. Blood samples were also collected on days 7 and 15. Only cows without a corpus luteum (CL) on day 0, and with a CL on days 7 and 15 remained in the experiment (EST, n=36; NOEST, n=48). On day 15, cows were randomly selected within each group (EST, n=29; NOEST, n=30) for conceptus collection via transcervical flushing, followed by endometrial biopsy in the uterine horn ipsilateral to the CL. Within cows not assigned to conceptus collection, blood samples were collected for whole blood RNA extraction (day 20) and pregnancy status was verified by transrectal ultrasonography (day 30). Diameter of dominant follicle on day 0 and plasma P4 concentrations on day 7 were greater (P⩽0.02) in EST v. NOEST cows. Conceptus length and messenger RNA (mRNA) expression of prostaglandin E synthase and interferon-tau were greater (P⩽0.04) in EST v. NOEST cows. Moreover, EST cows diagnosed as pregnant on day 30 had greater (P<0.01) blood mRNA expression of myxovirus resistance 2 on day 20 compared with NOEST. In summary, estrous expression near the time of FTAI enhanced pregnancy establishment factors in B. indicus cows, including conceptus development and mRNA expression of interferon-tau.     

Mixing aggression intensity is associated with age at first service and floor type during gestation,with implications for sow reproductive performance

Aggression resulting from mixing to establish a dominance hierarchy is a major welfare concern for group-housed sows. The associated stress can negatively impact aspects of reproductive performance. Objectives of this study were to investigate associations between 1) age at first service (AFS) and mixing aggression intensity in first parity sows, 2) mixing aggression intensity and reproductive performance within and between parity one and parity two, and 3) mixing aggression intensity, floor type during gestation and reproductive performance. Gilts (n = 160, hereafter referred to as sows) were mixed into stable groups of eight unfamiliar individuals approximately 4 days after artificial insemination, housed on fully slatted concrete (CON; n = 80) floor uncovered or covered with rubber slat mats (RUB; n = 80), and followed through two parities. Skin lesions (SLMIX; a proxy for the intensity of mixing aggression), were scored post mixing in each parity according to severity (0 = no lesions to 5 = severe lesions) on five body regions (ear, neck, hindquarter, rump, and belly) on the left and right sides, and at the tail/anogenital region. Total SLMIX score was calculated for each sow. Data on reproductive performance traits were acquired retrospectively from farm records for both parities. Two analyses were performed: 1) data from each parity were analysed separately and 2) SLMIX score in parity one was used to predict reproductive performance in parity two. Lower AFS was associated with a lower SLMIX score in parity one (P = 0.031). There was no association between SLMIX score and reproductive performance in parity one, while sows with higher SLMIX score in parity two had a higher proportion of piglets dead during lactation (P = 0.027) and a longer cycle length (P = 0.003) in parity two. Sows with higher SLMIX scores in parity one had more non-productive days (P < 0.001) in parity two. Concrete sows had a higher SLMIX score than RUB sows in parity one (P = 0.015), but not in parity two. In addition, CON sows had a higher proportion of piglets born dead (P = 0.013) compared with RUB sows in parity two. Mixing aggression has a negative influence on reproductive performance within parities, and it may also have a long-term negative carry-over effect on reproductive performance in subsequent parities. Serving gilts at younger ages could help to minimize the intensity of aggression at mixing, while housing on rubber flooring has beneficial implications for their reproductive performance.     

Part-time grouping of rabbit does in enriched housing: effects on performances,injury occurrence and enrichment use

Collective housing is perceived as a possible way to improve rabbit welfare, especially among adult females, which are normally individually housed. Part-time group housing seems to allow a better balance between welfare and health than continuous group housing, but practical implementation and consequences for reproductive performance have not been extensively studied. The aim of this work was to compare weight, feed intake, litter size, injury occurrence, body integrity, and spatial location of female rabbits housed part-time in group housing (PGH group, n = 32) or housed individually (IH group, n = 8). Females were grouped by opening connecting hatches between four individual enriched cages (platform, wood stick and gnawing block). Collective housing started 12 days after artificial insemination and was interrupted at the 10th day (instead of the 15th day later as originally planned) due to high injury rates and severe injuries caused by fighting. The proportion of injured females increased from 25% on the first day of grouping to 63% on the 10th day. Female weight gain during the experiment was similar in the two groups. Litter size at weaning was 9% lower in the PGH group than in the IH group (9.2 vs 10.0, P < 0.01). Platform use was recorded in 32% of the observations and was the highest during the 2 weeks before weaning (46% and 47% of total observations, P < 0.05). During the grouping period, there were at least two females in the same housing unit in 59.4% of the cases, at least two females were located on the same level in 31.3% of the cases. In conclusion, connecting individual cages is an ergonomic solution for part-time group housing, but does not prevent fights for the establishment of a social hierarchy. This is detrimental to the health and body integrity of female rabbits.     

Pharmacokinetics of eCG and induction of fertile estrus in bitches using eCG followed by hCG

The aim was to design a protocol combining eCG followed by hCG for estrus induction in the bitch. In Experiment 1, three ovariohysterectomized bitches received 10 000 IU of eCG iv, and 15 days later 10 000 IU of eCG im. Blood samples were taken up to 144 h after each injection to measure eCG concentrations. In Experiment 2, 25 healthy, intact late anestrous bitches were assigned to one of five doses of eCG (5, 10, 15, 20, 44, or 50 IU/kg eCG im; [TRT5-TRT50]). Sexual behavior (SB), clinical signs of estrus (CSE) and vaginal cytology (VC) samples were obtained and scored before eCG administration and every other day until onset of estrus, or for 14 days. In Experiment 3, intact late anestrous bitches were assigned to a treatment group (TRT; n = 16) and received eCG (50 IU/kg im) followed by hCG (500 IU im) 7 days later; or to a placebo group (PLA; n = 8) where they received 1 mL saline solution im. All bitches that were induced in estrus were mated or AI with fresh semen. In Experiment 1, maximum observed concentration (C_max) eCG were similar between im and iv routes (6.1 ± 0.9 vs. 8.6 ± 0.5 IU/mL, P > 0.08), whereas time for maximum observed concentration (T_max.) was longer for im compared to iv routes (17.5 ± 0.5 vs. 11.6 ± 0.3 h, P < 0.01). The area under the curve (AUC) was similar for im and iv routes (P > 0.48), and eCG was detectable in serum for at least 144 h for both routes. In Experiment 2, 3 days or 3 to 5 days after treatment, all bitches in TRT50 had higher scores compared to TRT5-44 animals (P < 0.01). In TRT50, the mean interval from treatment to estrus was 4.0 ± 0.4 days. In Experiment 3, the mean interval from treatment to estrus was shorter in the TRT group compared to the PLA group (4.1 ± 3.3 vs. 68.5 ± 4.4 days, P < 0.01). The previous interestrus interval was similar for TRT and PLA groups (199.6 ± 7.2 vs. 197.5 ± 10.2 days), but the new interestrus interval was shorter for the TRT compared to the PLA group (164.0 ± 7.2 vs. 212.2 ± 10.2 days; treatment by interval interaction, P < 0.007). Serum P₄ concentrations increased on the first day of cytologic diestrus after treatment in bitches in TRT (0.7 ± 0.3 vs. 22.8 ± 4.2 ng/mL; P < 0.01); but did not change in PLA (P > 0.84). Ninety-four percent of animals were bred (15/16; AI, n = 7; natural mating, n = 8), and 80% (12/15) became pregnant. None of the bitches had any side effects from the eCG and hCG therapy. We concluded that 50 IU/kg of eCG combined 7 days later with 500 IU of hCG was effective to induce normal and fertile estrus in bitches at 164 days post estrus, with an 80% pregnancy rate, with no side effects, and with a reduction of 48 days of the interestrus interval.     

Frequent range visits further from the shed relate positively to free-range broiler chicken welfare

Little is known about the implications of accessing an outdoor range for broiler chicken welfare, particularly in relation to the distance ranged from the shed. Therefore, we monitored individual ranging behaviour of commercial free-range broiler chickens and identified relationships with welfare indicators. The individual ranging behaviour of 305 mixed-sex Ross 308 broiler chickens was tracked on a commercial farm from the second day of range access to slaughter age (from 16 to 42 days of age) by radio frequency identification (RFID) technology. The radio frequency identification antennas were placed at pop-holes and on the range at 2.7 and 11.2 m from the home shed to determine the total number of range visits and the distance ranged from the shed. Chickens were categorised into close-ranging (CR) or distant-ranging (DR) categories based on the frequency of visits less than or greater than 2.7 m from the home shed, respectively. Half of the tracked chickens (n=153) were weighed at 7 days of age, and from 14 days of age their body weight, foot pad dermatitis (FPD), hock burn (HB) and gait scores were assessed weekly. The remaining tracked chickens (n=152) were assessed for fear and stress responses before (12 days of age) and after range access was provided (45 days of age) by quantifying their plasma corticosterone response to capture and 12 min confinement in a transport crate followed by behavioural fear responses to a tonic immobility (TI) test. Distant-ranging chickens could be predicted based on lighter BW at 7 and 14 days of age (P=0.05), that is before range access was first provided. After range access was provided, DR chickens weighed less every week (P=0.001), had better gait scores (P=0.01) and reduced corticosterone response to handling and confinement (P<0.05) compared to CR chickens. Longer and more frequent range visits were correlated with the number of visits further from the shed (P<0.01); hence distant ranging was correlated with the amount of range access, and consequently the relationships between ranging frequency, duration and distance were strong. These relationships indicate that longer, more frequent and greater ranging from the home shed was associated with improved welfare. Further research is required to identify whether these relationships between ranging behaviour and welfare are causal.