Influence of prepartum feed levels on colostrum production and farrowing performance in highly prolific sows in a tropical environment

Currently, there is a lack of data on the effects of altering feed levels on sow performance and piglet characteristics during the transition period in tropical environments. The present study determined the effect of sow feed levels during the transition period on colostrum yield, colostrum immunoglobulin (Ig) G, colostrum intake of piglets, farrowing duration, proportion of stillborn piglets per litter (SB) and the incidence of farrowing assistance in highly prolific sows. A total of 114 Landrace × Yorkshire crossbred sows and their offspring (n = 2 072) were included in the experiment. Sows were assigned to different feed supply levels from entry to farrowing at 110 days of gestation until farrowing based on their parity number. Three feed-level groups were the control group who received 3.0 kg/day of lactation feed (n = 40), treatment 1 group who received 3.6 kg/day of gestation feed (n = 39) and treatment 2 group who received 4.0 kg/day of lactation feed (n = 35). Colostrum samples (5 ml) were obtained from the sows within 3 h after the onset of farrowing for IgG assay. Piglets were weighed immediately after birth and then again 17-24 h later to estimate their colostrum intake. Colostrum yield was determined by aggregating the colostrum intake of piglets within the litter. The total number of piglets born, SB and farrowing duration were 18.2 ± 3.8, 7.5% and 259.1 ± 138.1 min, respectively. Among these sows, 28.9% experienced a farrowing duration exceeding 300 min and 50.9% required assistance during farrowing. Interestingly, piglets in the treatment 2 group demonstrated a greater colostrum intake (403.1 ± 14.9 g) compared to the control group (360.6 ± 15.1 g, P = 0.046) and the treatment 1 group (361.0 ± 12.9 g, P = 0.033). On average, colostrum yield of sows in the treatment 2 group tended to be higher than in the control group (+0.5 kg, P = 0.081), but did not differ from the treatment 1 group (+0.3 kg, P = 0.191). No significant differences in farrowing duration, SB, farrowing assistance, or colostrum IgG concentration were found across various feed-level groups (P > 0.05). In conclusion, the study showed that raising lactation feed by 1.0 kg/day prefarrowing increased piglet colostrum intake and tended to boost sow colostrum production, without significantly affecting farrowing duration, stillbirth rates, or need for assistance.

Butaphosphan and Cyanocobalamin Supplementation in Semen Extender on Chilled Boar Sperm Quality and Life Span

The objective of the present study was to determine the effect of butaphosphan and cyanocobalamin supplementation in semen extender on chilled boar sperm quality and life span. A total of 35 ejaculates of boar semen were included. The semen was diluted with Beltsville thawing solution extender supplemented with different concentrations of butaphosphan and cyanocobalamin [0 (control), 0.1, 0.2, 0.3, 0.4, and 0.5%] in the diluted semen. The semen samples were evaluated using a computer-assisted sperm analysis system to determine sperm motility and sperm kinetic parameters (i.e., the curvilinear velocity, VCL; straight line velocity, VSL; average path velocity, VAP; linearity, LIN; straightness, STR; amplitude of lateral head, ALH; wobble, WOB; and beat cross frequency, BCF). Additionally, sperm viability, acrosome integrity, mitochondrial activity, and plasma membrane integrity were evaluated after 4 (day 0), 72 (day 3), 120 (day 5), and 168 (day 7) h of storage using SYBR-14-ethidium homodimer-1 (EthD-1), EthD-1, JC-1, and the short hypo-osmotic swelling test, respectively. The analyses were carried out by using the general linear mixed model (MIXED) procedure of SAS. The statistical models for each data set included group, day after storage, and interaction between group and day after storage. The boar was included as a random effect. On day 0 after storage, progressive motility, VCL, VSL, VAP, and plasma membrane integrity of boar sperm in 0.3% of butaphosphan and cyanocobalamin supplementation were greater than those in the 0.4 and 0.5% groups (P < 0.05). On day 3 after storage, total motility and progressive motility, VCL, VSL, VAP, LIN, WOB, BCF, and plasma membrane integrity in 0.3% of butaphosphan and cyanocobalamin supplementation were significantly greater than those in the control group (P < 0.05). The total motility and progressive motility, VAP, and WOB in 0.3% of butaphosphan and cyanocobalamin supplementation were greater than those in the control group on day 5 after storage (P < 0.05). No effects of butaphosphan and cyanocobalamin supplementation on acrosome integrity and mitochondria activity were found on days 3, 5, and 7 after storage. However, the motility and progressive motility and the values for all sperm kinetic parameters except ALH in 0.3% of butaphosphan and cyanocobalamin supplementation were greater than those in the control group on day 7 after storage (P < 0.05). In conclusion, 0.3% of butaphosphan and cyanocobalamin supplementation in semen extender improved sperm motility, sperm activity, morphology, and life span in chilled boar sperm.

Impact of sow parity on yield and composition of colostrum and milk in Danish Landrace × Yorkshire crossbred sows

The present study aims to characterize the colostrum, milk yield and composition and to determine whether sow parity would influence yield and composition of colostrum and milk in Danish Landrace × Yorkshire crossbred sows. The data were collected from sow parity numbers 1 (n = 27), 2-4 (n = 48) and 5-6 (n = 30) from Danish Landrace × Yorkshire crossbred sows reared in a commercial swine herd in Thailand. The piglets were weighed on day 0 (<1 h), 1 (24 h), 3, 10 and 17 after birth to determine the colostrum and milk yields of the sows using a prediction equation. Milk samples were collected manually within 1 h of the onset of parturition and on days 3, 10 and 17 after farrowing to evaluate milk composition. A general linear model procedure was used to analyze the effects of sow parity numbers on colostrum yield and composition and a general linear mixed model procedure was used to analyze the effects of sow parity numbers on yield and composition of milk. The model included the fixed effects of sow parity number and time (day after parturition). The sow parity numbers 2-4 (7.0 kg) had a higher colostrum yield than 1st parity sows (5.4 kg, P =  0.002) and parity 5-6 sows (5.9 kg, P = 0.025). No evidence of parity differences was observed on milk yield (P = 0.306). No effect of sow parity numbers on fat, protein and lactose in milk was observed. The dry matter in sow parity numbers 2-4 (19.8 g/100 g) had a tendency to be higher than sow parity number 1 (18.6 g/100 g, P =  0.107) and 5-6 (18.4 g/ 100 g, P =  0.053). In conclusion, sow parity number had an impact on colostrum yield in Danish Landrace × Yorkshire crossbred sows in a tropical climate but did not influence colostrum, milk composition and milk yield. Colostrum yield in Danish Landrace × Yorkshire crossbred sows was the highest in sow parity numbers 2-4.

52 Difference of Seminal Plasma Proteins in Good- and Poor-Freezability Boar Ejaculates

Seminal plasma is the semen components that maintain sperm metabolism, pH and osmolality. Fibronectin (FN1) and glutathione peroxidase (GPX5) are the seminal plasma proteins that play an important role on the boar sperm functions. The purpose of the present study was to determine the differences in GPX5 and FN1 contents in the boar semen having good, moderate, and poor freezability. A total of 38 ejaculates from 25 boars with proven fertility were included in the experiment. All the ejaculates included in the study had >70% subjective motility, >75% normal morphology, >75% sperm viability, and volume >100 mL per ejaculate. The semen was collected through semen collection bag with filter and split into 2 portions. The first portion was prepared for the evaluation of seminal plasma proteins (i.e. GPX5 and FN1) and the second portion was cryopreserved and evaluated for post-thaw semen qualities. The seminal plasma samples were collected in cryotube and plug into liquid nitrogen. The samples was stored at –80°C before protein extraction. After thawing, the ejaculates were classified into 3 groups according to their post-thawed sperm motility: poor (14.6 ± 3.9%), modersate (28.5 ± 4.1%), and good (64.0 ± 8.7%) freezability. The amounts of GPX5 and FN1 proteins were evaluated through Western blot analysis. The normalized quantity of proteins was compared among groups by one-way ANOVA. The normalized level of FN1 in seminal plasma was higher in good- than in poor-freezability groups (8.0 ± 0.8% v. 5.7 ± 0.7%, respectively; P < 0.05), but did not differ significantly compared with that of the moderate-freezability group (7.5 ± 0.8%; P > 0.05). The levels of GPX5 in good-, moderate-, and poor-freezability groups were 14.7 ± 3.0%, 16.8 ± 3.2%, and 10.9 ± 3.0%, respectively (P > 0.05). The level of FN1 in seminal plasma was significantly correlated with the post-thaw sperm progressive motility (r = 0.38, P = 0.01), total motility (r = 0.37, P = 0.02), and the proportion of bent tail sperm (r = –0.33, P = 0.04). The level of GPX5 was not correlated with any of the post-thaw sperm qualities (P > 0.05). However, the levels of GPX5 was positively correlated with FN1 (r = 0.40, P = 0.01, n = 38). It can be concluded that FN1 in seminal plasma can be used as a marker of sperm freezability in boar.

Effect of oral supplementation with different energy boosters in newborn piglets on pre-weaning mortality, growth and serological levels of IGF-I and IgG

Oral supplements are commonly used in commercial herds to improve energy status and passive immune acquisition of newborn piglets. However, there is little scientific evidence on the efficacy of oral supplements for piglets. The objective of this experiment was to study the effects of 2 oral supplementation products on piglet pre-weaning mortality and growth. A total of 62 litters (749 piglets) were distributed according to the sow's parity among 3 treatments: 1) CONTROL group, no oral supplementation to piglets; 2) EN group, light piglets (LP: birth BW ≤ 1.35 kg) received 2 doses of 1 mL Lianol Colostro; 3) COLO group, LP received 2 doses of 5 mL ColoBoost. Treatments were administered within 4 h after birth and repeated 8 h after the first dose. Piglets were weighed at d 0, 1, 10, and 21 after birth. Piglet rectal temperature was recorded shortly after birth and at 24 h. Cross-fostering was performed 24 h after birth. Blood samples were obtained from 39 LP at d 5 and 21 to determine IGF-I and IgG levels. Total mortality and LP mortality rate (percentage of LP in the litter that died) were recorded. At d 1, the EN group had a lower total mortality rate (2.1 vs. 7.1 ± 1.4%, = 0.036) and LP mortality rate (4.5 vs. 11.1 ± 2.8%, = 0.047) than the CONTROL group. At d 1, the COLO group tended to have a lower LP mortality rate than the CONTROL group (8.4 vs. 11.1 ± 3.0%, = 0.058). After cross-fostering, the COLO group had a lower LP mortality rate at d 21 than the CONTROL group (6.3 vs. 18.3 ± 2.8%, = 0.043). The total mortality rate and piglet body weight did not differ among groups at d 21. Piglets in the COLO group had a higher IgG level at d 5 than those in the EN group (24.9 vs. 16.3 ± 2.15 mg/mL, = 0.034) and tended to be higher than those in the CONTROL group (24.9 vs. 17.7 ± 2.35 mg/mL, = 0.072). Piglets in the EN group had a higher serum IGF-I concentration than those in the CONTROL group at d 21 (137.6 vs. 100.3 ± 11.15 ng/mL, = 0.030). The results suggested that 2 doses of oral supplementation within 12 h after birth might be effective in increasing small piglet survival and improving their IGF-I or IgG levels during lactation without compromising litter growth.

Apoptotic Cell Localization in Preantral and Antral Follicles in Relation to Non-cyclic and Cyclic Gilts

The objective of this study was to determine apoptotic cell localization in preantral and antral follicles of porcine ovaries. Additionally, the proportion of cells undergoing apoptosis was also compared between delayed puberty gilts and normal cyclic gilts. Ovarian tissues were obtained from 34 culled gilts with age and weight of 270.1 ± 3.9 days and 143.8 ± 2.4 kg, respectively. The gilts were classified according to their ovarian appearance as 'non-cyclic' (n = 7) and 'cyclic' (n = 27) gilts. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay was used to determine apoptotic cell expression in different compartments of the ovarian tissue sections. All apparent preantral (n = 110) and antral (n = 262) follicles were evaluated using image analysis software. It was found that apoptotic cells were expressed in both granulosa (22.2%) and theca cell layers (21.3%) of the follicles in the porcine ovaries. The proportion of apoptotic cells in the granulosa layer in the follicles was positively correlated with that in the theca layer (r = 0.90, p < 0.001). Apoptosis did not differ significantly between preantral and antral follicles in either granulosa (27.8% and 26.4%, p > 0.05) or theca cell layers (28.6% and 26.5%, p > 0.05). The proportion of apoptotic cells in non-cyclic gilts was higher than cyclic gilts in both granulosa (31.7% and 22.6%, p < 0.001) and theca cell layers (34.8% and 20.2%, p < 0.001). This study indicated that apoptosis of the granulosa and theca cell layers in the follicles was more pronounced in the ovarian tissue of delayed puberty gilts than cyclic gilts. This implied that apoptosis could be used as a biologic marker for follicular development/function and also that apoptosis was significantly associated with anoestrus or delayed puberty in gilts, commonly observed in tropical climates.

Prostaglandin F2α and control of reproduction in female swine: a review

In female swine, PGF2α is an important regulator of corpora luteal (CL) function, uterine contractility, ovulation, and embryo attachment. High affinity PGF2α receptors are present in the CL at all stages of the estrous cycle and they are functional. Therefore, a lack of luteolytic capacity of PGF2α is related to other factors that have not been well identified. In female pigs, a single exogenous PGF2α injection produces a short lasting decrease in plasma progesterone levels but does not induce luteolysis before day 12 of the estrous cycle. However, multiple injections of PGF2α can induce luteolysis before day 12 of the estrous cycle and may be utilized in the development of protocols for ovulation synchronization and timed AI. Most commonly, PGF2α is used for the induction of farrowing and so facilitation of cross fostering. Further, since PGF2α is a smooth muscle stimulant, treatment to stimulate myometrial contractions and uterine evacuation of residual products from parturition or infectious debris, may have beneficial effects on post-weaning fertility. Administration of PGF2α at the moment of insemination has been shown to improve reproductive performances when fertility is otherwise low, such as in sow under summer heat stress.

15 INTRAUTERINE INSEMINATION USING FROZEN - THAWED BOAR SEMEN IN SPONTANEOUS AND INDUCED OVULATING SOWS UNDER FIELD CONDITIONS

Intrauterine insemination (IUI) using frozen-thawed (FT) boar semen has yet to be reported. The objective of the present study was therefore to evaluate the 24-day nonreturn rate (NR), farrowing rate (FR), number of total piglets born/litter (TB), and number of live born piglets/litter (BA) after IUI with FT boar semen in spontaneous and induced ovulating sows. Ejaculates collected from each of 6 boars [3 Landrace (L) and 3 Yorkshire (Y)] were cryopreserved separately and used to produce LY crossbred offspring. Each batch of qualifying FT semen (≥30% motility) was divided and used in both groups, to minimize an individual boar variation effect. Thawed semen containing 1 × 109 motile spermatozoa extended in 20 mL of Beltsville Thawing Solution extender was flushed into the uterine body (20 mm beyond the cervix) via IUI device (Deep goldenpig™ catheter, IMV Technologies, L’Aigle, France). Forty multiparous sows (20 L and 20 Y) with weaning to estrus interval of 3 to 7 days were randomly assigned to 1 of 2 groups: spontaneously ovulating sows (10 L and 10 Y) and hCG-induced ovulating sows (10 L and 10 Y). The sows with spontaneous ovulation did not receive any treatment. The induced ovulating sows were given 750 IUhCG i.m. at detection of estrus. Ovulation was investigated every 12 h using transrectal ultrasonography. Time of ovulation was determined as 6 h before the first time when preovulatory follicles were not found. Insemination was conducted at 24 h after the detection of estrus and repeated every 12 h until ovulation took place in the spontaneous ovulation group and at 36, 42, and/or 48 h after hCG administration in the induced ovulation group. The statistical analyses were carried out using SAS software (version 9.0, SAS Institute, Cary, NC, USA.). The interval from detection of estrus to ovulation (EOI), TB, and BA were compared between the groups using Student’s t-test; and NR and FR between groups were compared using chi-square test. P < 0.05 was considered statistically significant. The results revealed that sow breed and sow breed interacted with group had no influence on any parameter assessed (P > 0.05). The average EOI differed significantly between spontaneous ovulation (40.2 h) and induced ovulation groups (35.6 h; P = 0.01). Moreover, variation of EOI among sows within each group seemed to be lower in the induce ovulation (4.5 h SD) than in spontaneous ovulation (5.5 h SD; P = 0.5). The number of inseminations per sow was 2.9 ± 0.6 (2 to 4 times) in spontaneously ovulating sows and was 2.4 ± 0.5 (2 to 3 times) in induced ovulating sows. No significant differences (P > 0.05) were found in the NR (80 v. 85%), FR (60 v. 65%), TB (8.0 ± 2.8 v. 9.4 ± 3.7 piglets/litter), and BA (7.8 ± 2.8 v. 8.7 ± 3.7 piglets/litter) between spontaneous and induced ovulating sows. In conclusion, IUI with a low number of FT boar spermatozoa provided fairly good NR and reasonable FR and TB in both spontaneous and induced ovulating sows. The number of inseminations required to attain acceptable fertility tended to be lower in the weaned sows with induced ovulation.

403 CONTROL OF OVULATION IN SOWS IN THE TROPICAL ENVIRONMENT USING HUMAN CHORIONIC GONADOTROPHIN IN COMPARISON WITH GONADOTROPIN-RELEASING HORMONE ANALOG

The reproductive performance of sows is influenced by numerous factors, including environment. The time of ovulation in response to hormonal treatment might vary depending on climate. Because control of ovulation in pigs using hormonal treatments has not been studied in the tropical climate, the effect of hCG or GnRH analog (buserelin) on the time of ovulation in weaned sows was investigated. Thirty-three multiparous Landrace (L; n = 14) and Yorkshire (Y; n = 19) sows housed in the mating and gestation unit on a commercial swine farm in Thailand were used. The average of maximum and minimum daily temperature and daily humidity during experiment was 35°C and 25°C and 31%, respectively. Estrus detection by back pressure test and presence of a mature boar was performed every 6 h. Only sows with weaning to estrus interval (WOI) of ≤7 days were studied. Estrous sows were randomly allocated to 3 groups: a control group (4 Y and 6 L), which was given no treatment; a group (5 Y and 5 L) given 750 IU of hCG i.m. at the beginning of estrus (hCG group); and a group (5 Y and 8 L) given 10 μg of GnRH analog i.m. at the beginning of estrus (GnRH group). The mean time of ovulation was monitored by transrectal ultrasonography every 6 h from the onset of estrus. Interval from onset of estrus to mean time of ovulation (EOI) was analyzed using general linear model procedures of SAS (version 9.0; SAS Institute, Cary, NC, USA). Least squares means and standard deviations of EOI were compared using ANOVA. The proportion of sows ovulating within 45 h after onset of estrus was compared using Fisher’s exact test. Differences with P < 0.05 were considered significant. All of the sows in the control and hCG groups ovulated within 5 days after onset of estrus, but 3 out of 13 (23%) sows in the GnRH group developed cystic follicles; these 3 sows were excluded from the analyses. Overall, WOI was 3.8 ± 0.9 days and did not differ among the groups (P ± 0.05). The breed of sow had no effect on the EOI (P ± 0.05). Although the EOI did not differ among the control (43.0 ± 19.2 h), hCG (40.2 ± 5.5 h), and GnRH (37.5 ± 10.3 h) groups (P ± 0.05), variation was less (P = 0.001) after administration of hCG or GnRH. In addition, the proportions of sows that ovulated within 45 h after onset of estrus in the hCG (9/10 sows) and GnRH (8/10 sows) groups tended to be higher than in the control group (5/10 sows; P = 0.10). In conclusion, results indicate that both hCG and GnRH are efficacious in inducing ovulation at a predictable time in weaned, spontaneously estrous sows. The occurrence of follicular cysts in GnRH-treated sows requires further investigation.

Expression of progesterone receptor in the utero-tubal junction after intra-uterine and deep intra-uterine insemination in sows

The aim of this study was to investigate the expression of progesterone receptor (PR) in the utero-tubal junction (UTJ) of sows at 24 h after intra-uterine insemination (IUI) and deep intra-uterine insemination (DIUI) compared with conventional artificial insemination (AI) in pigs. Fifteen multiparous sows were used: AI (n = 5), IUI (n = 5) and DIUI (n = 5). The sows were inseminated with a single dose of diluted semen during the second oestrus after weaning at 6-8 h prior to ovulation (AI: 3000 × 10(6) spermatozoa, IUI: 1000 × 10(6) spermatozoa and DIUI: 150 × 10(6) spermatozoa). The UTJ was collected and subject to immunohistochemical staining using avidin-biotin immunoperoxidase technique with mouse monoclonal antibody to PR. In the oviductal part of the UTJ, the intensity of PR in the tunica muscularis and the proportion of PR-positive cells in the surface epithelium after DIUI were lower than AI (p < 0.05). The intensity and the proportion of PR-positive cells between AI and IUI in all compartments of the UTJ did not differ significantly (p > 0.05). When comparing between tissue compartments, prominent staining was observed in the muscular layer of the UTJ. It could be concluded that the expression of PR in the UTJ prior to fertilization after DIUI with a reduced number of spermatozoa was lower than that after AI. This might influence sperm transportation and the fertilization process.

Number of spermatozoa in the crypts of the sperm reservoir at about 24 h after a low-dose intrauterine and deep intrauterine insemination in sows

The aim of this study was to investigate the number of spermatozoa in the crypts of the utero-tubal junction (UTJ) and the oviduct of sows approximately 24 h after intrauterine insemination (IUI) and deep intrauterine insemination (DIUI) and compared with that of conventional artificial insemination (AI). Fifteen crossbred Landrace x Yorkshire (LY) multiparous sows were used in the experiment. Transrectal ultrasonography was performed every 4 h to examine the time of ovulation in relation to oestrous behaviour. The sows were inseminated with a single dose of diluted fresh semen by the AI (n = 5), IUI (n = 5) and DIUI (n = 5) at approximately 6-8 h prior to the expected time of ovulation, during the second oestrus after weaning. The sperm dose contained 3000 x 10(6) spermatozoa in 100 ml for AI, 1,000 x 10(6) spermatozoa in 50 ml for IUI and 150 x 10(6) spermatozoa in 5 ml for DIUI. The sows were anaesthetized and ovario-hysterectomized approximately 24 h after insemination. The oviducts and the proximal part of the uterine horns (1 cm) on each side of the reproductive tracts were collected. The section was divided into four parts, i.e. UTJ, caudal isthmus, cranial isthmus and ampulla. The spermatozoa in the lumen in each part were flushed several times with phosphate buffer solution. After flushing, the UTJ and all parts of the oviducts were immersed in a 10% neutral buffered formalin solution. The UTJ and each part of the oviducts were cut into four equal parts and embedded in a paraffin block. The tissue sections were transversely sectioned to a thickness of 5 mum. Every fifth serial section was mounted and stained with haematoxylin and eosin. The total number of spermatozoa from 32 sections in each parts of the tissue (16 sections from the left side and 16 sections from the right side) was determined under light microscope. The results reveal that most of the spermatozoa in the histological section were located in groups in the epithelial crypts. The means of the total number of spermatozoa in the sperm reservoir (UTJ and caudal isthmus) were 2296, 729 and 22 cells in AI, IUI and DIUI groups, respectively (p < 0.01). The spermatozoa were found on both sides of the sperm reservoir in all sows in the AI and the IUI groups. For the DIUI group, spermatozoa were not found on any side of the sperm reservoir in three out of five sows, found in unilateral side of the sperm reservoir in one sow and found in both sides of the sperm reservoir in one sow. No spermatozoa were found in the cranial isthmus, while only one spermatozoon was found in the ampulla part of a sow in the IUI group. In conclusion, DIUI resulted in a significantly lower number of spermatozoa in the sperm reservoir approximately 24 h after insemination compared with AI and IUI. Spermatozoa could be obtained from both sides of the sperm reservoir after AI and IUI but in one out of five sows inseminated by DIUI.

Relationships among specific reasons for culling, reproductive data, and gross morphology of the genital tracts in gilts culled due to reproductive failure in Thailand

The present study aims to investigate genital organs of replacement gilts culled due to reproductive failure, and the relationship between gross morphological findings and historical reproductive data. The study was conducted from July 2005 to September 2006 and included a random sample of 200 genital organs from six swine herds in Thailand. Historical data and the reasons for culling were analyzed. Gross morphological examinations focused on the normality and abnormalities of the ovaries, as well as the remainder of the reproductive tract. Descriptive statistics and frequency analysis were conducted for all reproductive parameters. On average, the gilts were culled at 321.2+/-51.1d of age, at a body weight of 145.3+/-24.2kg. Gilts expressed first estrus at 253.2+/-32.7d and were artificially inseminated for the first time at 268.2+/-30.8d of age. The interval from entry to culling averaged 96.9+/-53.7d. Reasons for culling included anestrus (44.0%), vaginal discharge (20.5%), repeat breeding (15.5%), not being pregnant (10.0%), and miscellaneous causes (10.0%). Overall, 50.5% of gilts had normal genital organs, whereas 49.5% had at least one abnormality. Abnormalities of the ovary, oviduct, uterus, cervix and vagina-vestibule were found in 15.5%, 14.0%, 22.0%, 16.2%, and 17.6% of the gilts, respectively. The most common post-mortem abnormalities included endometritis (14.0%), cystic ovaries (10.5%) and congenital abnormalities of the reproductive tract (8.0%). Of the gilts culled due to anestrus, 52.2% were pre-pubertal. Most of the gilts culled due to vaginal discharge or repeat breeding had been cycling (90.2% and 96.8%, respectively).

Distribution of spermatozoa and embryos in the female reproductive tract after unilateral deep intra uterine insemination in the pig

The present study was performed to investigate the number of either the spermatozoa or the embryos in the reproductive tracts of sows after unilateral, deep, intra uterine insemination (DIUI). Two experiments were conducted, 10 sows were used in experiment I and eight sows were used in experiment II. Transrectal ultrasonography was used to examine the time when ovulation took place in relation to oestrus behaviour. The sows were inseminated with a single dose of diluted fresh semen 6-8 h prior to expected ovulation, during the second oestrus after weaning. In experimental I, five sows were inseminated by a conventional artificial insemination (AI) technique using 100 ml of diluted fresh semen, containing 3000 x 10(6) motile spermatozoa and five sows were inseminated by the DIUI technique with 5 ml of diluted fresh semen, containing 150 x 10(6) motile spermatozoa. The sows were anesthetized and ovario-hysterectomized approximately 24 h after insemination. The oviducts and the uterine horns on each side of the reproductive tracts were divided into seven segments, namely ampulla, cranial isthmus, caudal isthmus, utero-tubal junction (UTJ), cranial uterine horn, middle uterine horn and caudal uterine horn. Each segment of the reproductive tracts was flushed with Beltsville thawing solution (BTS) through the lumen. The total number of spermatozoa in the flushing from each segment were determined. In experimental II, eight sows were inseminated by the DIUI technique using 5.0 ml diluted fresh semen containing 150 x 10(6) motile spermatozoa. The sows were anesthetized 61.1 +/- 12 h after insemination (48-72 h) and the embryos were flushed from the oviduct through the proximal part of the uterine horn. It was revealed that, in experimental I, the spermatozoa were recovered from both sides of the reproductive tract in the AI-group, and from unilateral side of the reproductive tract in the DIUI-group (three sows from the left and two sows from the right sides). The number of spermatozoa recovered from the reproductive tracts was higher in the AI- than the DIUI-group (p < 0.001). In experiment II, fertilization occurred in five of eight sows (62.5%) after DIUI. The number of ova that ovulated were 16.4 +/- 2.6 per sow and the embryos numbering 11.4 +/- 2.3 per sow were recovered from both sides of the reproductive tract. In conclusion, the spermatozoa given by DIUI could be recovered from only one side of the reproductive tract of sows at approximately 24 h after DIUI via the flushing technique. However, embryos were found in both sides of the oviducts and the proximal part of the uterine horns 48-72 h after insemination, indicating that the fertilization occurred in both sides of the oviducts.

Seasonal and breed effects on reproductive parameters in bitches in the tropics: a retrospective study

OBJECTIVES

To investigate the influence of season and breed on reproductive parameters in bitches raised under tropical climatic conditions.

METHODS

Over a seven year period, from 1998 to 2004, 310 oestrous periods of 53 bitches were observed. The dogs were of various breeds; dobermann (number of bitches/number of oestrous cycles) (n=2/19), German shepherd dog (n=35/211), Labrador retriever (n=14/68) and Rottweiler (n=2/12). In 250 of the 310 oestrous periods, natural matings took place on days 9 and 11 after the onset of pro-oestrus. The whelping rate was analysed for bitches of each breed. Variables, including breed and the whelping rate, by month of the year, were used for analysis of the inter-oestrus interval, gestation length, total number of pups born, number of live pups born and the weight of the pups at birth.

RESULTS

A low frequency of oestrous activity was found during the summer. Breeding dogs in the summer resulted in a low whelping rate. No difference (P>0.05) was seen in the whelping rate of each breed: dobermann (70.5 per cent), German shepherd dog (61.5 per cent), Labrador retriever (67.9 per cent) and Rottweiler (100 per cent). The Labrador retriever had a longer inter-oestrus interval (252 [114] and 190 [61] days) (P<0.01) and a larger litter size (8.2 [1.8] and 6.6 [2.8]) (P<0.05) than the German shepherd dog.

CLINICAL SIGNIFICANCE

The environmental factors in summer tend to reduce oestrus incidence and fertility in the bitches. According to litter size, the Labrador retriever seems to have a more efficient reproductive performance than the German shepherd dog. The Labrador retriever had a longer inter-oestrus interval than the German shepherd dog.

Sperm distribution in the reproductive tract of sows after intrauterine insemination

The purpose of the present study was to compare the number of spermatozoa obtained from different parts of the oviducts and the uterine horns of sows after intrauterine insemination (IUI) and conventional artificial insemination (AI), 24 h after insemination. Twelve crossbred (Landrace x Yorkshire) multiparous sows were used in the experiment. The sows were examined for standing oestrus using a back pressure test and were examined every 4 h after standing oestrus by real-time B-mode ultrasonography to estimate the time of ovulation. The sows were allocated to two groups, group I sows (n = 6) were inseminated by a conventional AI technique with 3 x 10(9) motile spermatozoa in 100 ml of extended semen, and group II sows (n = 6) were inseminated by an IUI technique using 1 x 10(9) motile spermatozoa in 50 ml of extended semen. A single dose of AI or IUI was given using the same boar, 8-10 h before the expected time of ovulation during the second oestrus after weaning. Twenty four hours after insemination, the sows were ovario-hysterectomized. The oviducts and the uterine horns were removed and divided into seven parts, the cranial, middle and caudal uterine horns, the utero-tubal junction (UTJ), the cranial and caudal isthmus, and the ampulla. All parts of the reproductive tract were flushed and the spermatozoa were counted using a haemocytometer. The results revealed that the spermatozoa were found in both the oviducts and the uterine horns in all animals. The number of flushed spermatozoa in the UTJ of groups I and II, was 142,500 and 131,167 (p > 0.05), and in the caudal isthmus was 1411 and 1280 (p > 0.05), respectively. The proportion of spermatozoa in different parts of the reproductive tract in relation to the total number of spermatozoa within the tract was not significantly different between groups I and II (p > 0.05). It could be concluded that IUI, with a three-time reduction in the number of spermatozoa used resulted in the same number of spermatozoa to be deposited in the sperm reservoir around ovulation time.

Age, body weight and backfat thickness at first observed oestrus in crossbred Landrace x Yorkshire gilts, seasonal variations and their influence on subsequence reproductive performance

The objective of the present study was to investigate puberty attainment in crossbred Landrace x Yorkshire (LY) gilts reared under tropical conditions and their subsequent reproductive performance. This study was carried out in a 2400-sow herd over a 1-year period. A total of 696 crossbred LY replacement gilts were included. Faecal samples from 214 gilts were collected to determine the faecal progesterone profiles around the time of first oestrus. Solid-phase 125I-radioimmunoassay was used to determine the progesterone concentrations in the faecal extract. The gilts entered the herd at an average age of 177.5 +/- 12.6 days, 95.7 +/- 10.2 kg body weight (BW) and a backfat thickness (BF) of 12.0 +/- 2.9 mm. On average, the gilts expressed first standing oestrus at 195 days of age, 106 kg of BW and a BF of 13.0 mm. The interval from entry to the gilt pool to the first observed oestrus (EOI) was 24.4 +/- 18.0 days (range 0-88 days). The hormonal profile indicated that the gilts that actually ovulated during the first observed oestrus was 34% (group A), the gilts that had ovulated before the first observed oestrus was 21% (group B) and the gilts that did not ovulate during the first observed oestrus was 45% (group C). During summer the proportion of group A gilts was significantly lower than during the winter and the rainy seasons (P < 0.05). The BW of gilts at entry significantly correlated with the BF at entry (r = 0.31, P < 0.001), the age at entry (r = 0.47, P < 0.001), the BW at first oestrus (r = 0.65, P < 0.001) and the BF at first oestrus (r = 0.33, P < 0.001). An increase of BW at entry of 1 kg resulted in a decrease of EOI of 0.28 days. The age, BW and BF of gilts at the first observed oestrus significantly influenced the total number of piglets born per litter (TB) and the number of piglets born alive per litter (BA) in the first three parities. Gilts expressing their first oestrus between 181 and 200 days had a significantly larger TB than gilts that expressed first oestrus between 150 and 180 days (P = 0.03) and between 201 and 220 days (P = 0.003). Gilts that showed first oestrus between 110.1 and 120.0 kg had a larger TB and BA than gilts that showed first oestrus between 80.0 and 100.0 kg (P < 0.05). Gilts that showed first oestrus with a BF between 13.1 and 15.0 mm had a larger TB and BA than gilts that showed first oestrus with a BF between 11.1 and 13.0 mm (P < 0.05). Group A gilts had a significantly larger TB than group B (10.5 piglets/L versus 9.4 piglets/L, P = 0.02), while farrowing rate (FR) did not differ significantly among groups A, B and C (78.1, 76.9 and 77.6%, respectively). Gilts that farrowed in the summer had a larger TB and BA than gilts that farrowed in the winter (TB, P = 0.03; BA, P = 0.09) and the rainy season (TB, P = 0.006; BA, P = 0.003). In conclusion, LY gilts reared under tropical conditions expressed first standing oestrus at 195 days of age, 106 kg BW and a BF of 13.0 mm. Under field conditions, 21% of the gilts with an observed oestrus had ovulated. The proportion of gilts that showed first oestrus and ovulated normally was lowest during the summer. The age, BW and BF at first observed oestrus influenced subsequent reproductive performance over the first three parities. The mean litter size (TB and BA) in the first three parities were highest in gilts that had a first observed oestrus between 181 and 200 days with 110.1-120.0 kg BW and 13.1-15.0 mm BF.

Hormonal profiles and embryo survival of sows subjected to induced stress during days 13 and 14 of pregnancy

Group housing of sows during the mating and gestation period has become the overall common management practice in Sweden. Loose housing is probably less stressful for the animals because it allows them more opportunities to behave naturally, but mixing unfamiliar sows does create a stressful situation due to aggressive interactions, which can lead to food deprivation. The objective of the present study was to investigate and compare the effects of stress in form of food deprivation and ACTH administration at days 13 and 14 of pregnancy (day 1, first day of standing oestrus) in sows. The hormonal secretion of the sows and foetal survival by day 30 of pregnancy was, therefore, studied in 17 crossbred multiparous sows. The sows were randomly allocated into three different groups: one control (C-) group; one food deprived (FD-) group, which was deprived of food from the morning of day 13 of pregnancy until the evening meal on day 14; and a third group (A-), which was given intravenous injections of synthetic ACTH (Synachten Depot), at a dose of 0.01 mg/kg body weight every sixth hour from 6 a.m. on day 13 until 6 a.m. on day 15 of pregnancy. All sows were slaughtered at 30 +/- 2 day of pregnancy and the genital tracts recovered. Total number of corpora lutea (CL), total number of viable or nonviable embryos and foetal survival rates were determined. Samples from the peripheral blood circulation were collected four times a day from day 12 until slaughter, except during days 13-15 when blood was collected every second hour. The blood samples were analysed for cortisol, progesterone, oestrone, prostaglandin F(2alpha)-metabolite, oestrone-sulphate, insulin, free fatty acids and triglycerides. FD-sows had increased levels of cortisol, free fatty acids and progesterone, as well as a lowered level of insulin in the peripheral blood plasma, while A-group sows had increased levels of both cortisol and insulin compared with the C-group. Treatment with ACTH seemed to cause a 2-day delay in the increase of oestrone, from day 19, as seen in the FD- and C-group, to day 21 of pregnancy. At the time of slaughter, there were no significant differences among groups in terms of total number of foetuses and foetal survival rate. The results of the present study suggest a capacity of the sow to compensate for the influence of induced moderate stress at the time of pregnancy when maternal recognition occurs.

Repeat breeding and subsequent reproductive performance in Swedish Landrace and Swedish Yorkshire sows

The objective of the present study was to analyse the association between repeat breeding (RB) in gilts/sows and their subsequent reproductive performance as well as the impact of interactions between repeat breeding and factors like parity number, boar breed, season and mating type (MT) on subsequent reproductive performance in Swedish Landrace (L) and Swedish Yorkshire (Y) sows. Data analysed included 7040 sows (3654 L and 3386 Y), farrowing during January 1994 until December 1999 in 11 L and 8 Y nucleus herds. The study was assigned as a cohort design and the aim was to study gilts/sows from their first mating as gilts until mating after third parity. Analysis of variance was applied to continuous data and logistic regression was applied to categorical data. Percentages of litters as a result of repeat breeding in sow parities 1-3 were 6.1, 12.0 and 6.3% for L sows and 6.7, 13.1 and 7.4% for Y sows. For parity 3, the incidence of litters resulting from repeat breeding was significantly higher (P<0.001) in Y than in L sows. The proportion of irregular return to oestrus (>24 days after first mating) was higher (P<0.01) in primiparous sows than in multiparous sows (69% versus 61%). On average, litters resulting from repeat breeding were larger (P<0.001) than litters resulting from non-repeat breeding (NR) (about 0.5 piglets per litter) in both L and Y sows. For Y sows, if the previous litter was a result of repeat breeding, the subsequent reproductive cycle had 2.7% higher RR (P<0.05) and 2.4% lower FR (N.S.) compared with sows that were not repeat bred. The same trend was found in L sows (1.4% higher RR and 1.3% lower FR) but the differences were not significant. Among the sows removed from the herds, about 24% of L and 28% of Y were culled due to reproductive problems (gilts not included). In addition, a number of sows from these nucleus herds were also culled due to low breeding value and poor conformation.

Effect of birth litter size, birth parity number, growth rate, backfat thickness and age at first mating of gilts on their reproductive performance as sows

The present study was performed to evaluate retrospectively the influence of birth litter size, birth parity number, performance test parameters (growth rate from birth to 100kg body weight and backfat thickness at 100kg body weight) and age at first mating (AFM) of gilts on their reproductive performance as sows. Traits analysed included remating rate in gilts (RRG), litter size, weaning-to-first-service interval (WSI), remating rate in sows and farrowing rate (FR). Data were collected from 11 Swedish Landrace (L) and 8 Swedish Yorkshire (Y) nucleus herds and included 20712 farrowing records from sow parities 1-5. Sows that farrowed for the first time during 1993-1997, having complete records of performance test and AFM, were followed up to investigate their subsequent reproductive performance until their last farrowing in 1999. Analysis of variance and multiple regression were applied to continuous data. Logistic regression was applied to categorical data. The analyses were based on the same animals and the records were split into six groups of females, i.e. gilts, primiparous sows, and sows in parities 2-5, respectively. Each additional piglet in the litter in which the gilt was born was associated with an increase of her own litter size of between 0.07 and 0.1 piglets per litter (P<0.001). Gilts born from sow parity 1 had a longer WSI as primiparous sows compared with gilts born from sow parity 4 (0.3 days; P<0.05) or parity 5 (0.4 days; P<0.01). Gilts with a higher growth rate of up to 100kg body weight had a larger litter size (all parities 1-5; P<0.05), shorter WSI (all parities 1-5; P<0.05) and higher FR (parities 2 and 5; P<0.05) than gilts with a lower growth rate. Gilts with a high backfat thickness at 100kg body weight had a shorter WSI as primiparous sows (P<0.001) compared with low backfat gilts, and 0.1 piglets per litter more as second parity sows (P<0.01). A 10 day increase in AFM resulted in an increase in litter size of about 0.1 piglet for primiparous sows (P<0.001) and a decrease (P<0.05) for sow parities 4 and 5.

Factors influencing age at first mating in purebred Swedish Landrace and Swedish Yorkshire gilts

The aim of the present study was to retrospectively analyze causes of the variation in age at first mating in Swedish Landrace (L) and Swedish Yorkshire (Y) gilts. Production traits including growth rate from birth to 100kg body weight and backfat thickness at 100kg body weight were also studied. Data analyzed were obtained from 11 L and 11 Y nucleus herds and included gilts born during a 5-year-period from October 1993 until September 1998. The complete data set included information on 14,761 gilts (6997 L and 7764 Y). Traits analyzed included age of gilt at first mating, growth rate and backfat thickness. Seven statistical models were used for analyzing the data. Factors included were gilt breed, birth month, parity number and size of the litter in which the gilt was born as well as their interactions. Compared with Y gilts, L gilts grew faster (571 versus 556 g/day; P<0.001), had a thinner backfat (11.9 versus 12. 3mm; P<0.001) at 100kg body weight and were 12 days younger at first mating (237 versus 249 days; P<0.001). Birth month significantly (P<0.001) influenced age at first mating, growth rate and backfat thickness. Gilts born from smaller litters were mated at younger age than gilts born from larger litters even when age at first mating was adjusted for the effect of growth rate and backfat thickness. Growth rate of the gilts decreased when 'birth litter size' increased. Gilts born from primiparous sows grew slower, had a thinner backfat at 100kg body weight and were older at first mating compared with gilts born from multiparous sows. Gilts with a higher growth rate were younger at first mating than those with a lower growth rate. Gilts with a thicker backfat at 100kg body weight were mated earlier than the thin ones. However, the effect of growth rate on age at first mating was more pronounced in the gilts with a thinner backfat rather than the ones with a thicker backfat.