Unmated Gilts Research Articles

Causes of death of sows in three Brazilian pig farms

ABSTRACT: Sow mortality is directly related to financial losses and productive efficiency in pig farms. Despite this, diseases associated with the death of sows are poorly understood. This study aimed to determine the main causes of death of sows in Brazilian pig farms. To perform this research, three Brazilian pig farms were visited, and necropsies were performed on all sows that had died spontaneously or were subjected to euthanasia. Tissue fragments were collected for histopathological and bacteriological examination. In addition, the clinical signs, productive stage, parity, and type of death (spontaneous or euthanasia) were recorded. A total of 138 necropsies were performed, and 132 had a conclusive diagnosis. The most frequent productive stages were gestation and lactation (33.3 and 31.9%, respectively), followed by parturient sows (17.4%), cull sows (9.4%), weaning-to-estrus interval (WEI) (4.3%), and unmated gilts (3.6%). The most affected organ systems were reproductive (28%), digestive (25%), locomotor (22%), cardiovascular (9.1%), and hematopoietic (6.1%). The most frequently diagnosed conditions were uterine prolapse (16/132; 12.1%), gastric ulcer (13/132; 9.8%), suppurative arthritis (11/132; 8.3%), liver lobe torsion (11/132; 8.3%), heart failure (9/132; 6.8%), vaginal or vaginal and rectal prolapse (9/132; 6.8%), and pododermatitis (8/132; 6.1%). Although 58.2% of the deaths were due to one of these seven diseases, there was a great variability in diagnoses.

A herd management survey on culling guidelines and actual culling practices in three herd groups based on reproductive productivity in Japanese commercial swine herds1

The objective of the present study was to investigate culling guidelines for gilts and sows in Japanese commercial herds and to compare differences between culling guidelines and actual culling practices in different herd productivity groups. A questionnaire survey was undertaken to obtain information on culling guidelines in 115 commercial swine herds that participated in the PigCHAMP data-share program. The questionnaire included questions on guideline values for culling intervals and the number of conception failure occurrences that would trigger a culling decision to be made. Ninety-two of the 115 herds (80.0%) returned appropriate data for the study and were included in the present study. In addition to questionnaire data, culling data regarding the actual culling intervals and number of reservices for gilts and sows culled during 2007 to 2008 were also obtained for the same herds from a PigCHAMP database. Culled gilts and sows were divided into 4 female groups on the basis of the stages of their reproductive life when they were culled: unmated gilts, mated gilts, unmated sows, and mated sows. Culling intervals in unmated gilts and sows were defined as the number of days from birth or weaning to culling, respectively, whereas in mated gilts and sows culling intervals were the number of days from last service to culling. Three herd productivity groups were formed on the basis of the upper and lower 25th percentiles of pigs weaned mated female(-1)·yr(-1):high-,intermediate- or low-performing herds. For unmated gilts and sows actual culling intervals were 15 d shorter than the guideline culling intervals in the surveyed data submitted by producers (P < 0.05). This shorter actual culling period for unmated gilts and sows did not vary significantly between herd productivity groups in any parity. However, for mated gilts and sows the actual culling intervals were at least 30 d longer than the guideline culling intervals (P < 0.05). Guideline and actual culling intervals for mated gilts and sows were at least 10 d shorter in high-performing herds than in low-performing herds (P < 0.05). High-performing herds had lower proportions of sows culled after the second reservice than intermediate- or low-performing herds in parity groups 0 to 5 (P < 0.05). In conclusion, culling guidelines for mated sows differed between herd productivity groups, and culling guidelines for mated gilts and sows were not strictly followed in any herd group in the commercial herds.

Culling intervals and culling risks in four stages of the reproductive life of first service and reserviced female pigs in commercial herds

The objectives of this study were to measure culling intervals and culling risks in the four stages of the reproductive life of female pigs and to compare culling intervals between the number of services and between herd groups, based on herd productivity. We also compared survival patterns of females pigs between these herd groups. Our data set included lifetime records of 52,792 females born between 2001 and 2004 in 101 commercial herds. Two herd groups were selected on the basis of the upper 25th percentile of pigs weaned per mated female per 5 yr between 2002 and 2006, namely the high-performing herds, and ordinary herds. Culled females were also allocated into four groups based on the stages of their reproductive life when culled: unmated gilts, mated gilts, unmated sows, and mated sows. Culling intervals in unmated gilts and mated gilts were defined as the number of days from birth to culling and from first mating to culling, respectively. Culling intervals in unmated sows and mated sows were the number of days from weaning to culling. The number of services was categorized into two groups: first service and reservice groups. Multilevel linear mixed-effects models and survival analysis were performed. Culling intervals (±SEM) in unmated gilts, mated gilts, unmated sows, and mated sows were 302.9 ± 1.16, 98.4 ± 0.92, 14.3 ± 0.12, and 89.6 ± 0.42 d, respectively. Culling risks in the four groups were 5.6%, 7.1%, 58.0%, and 29.3%, respectively. In unmated gilts, mated gilts, and mated sows, the culling intervals in the high-performing herds were 43.0, 18.9, and 16.0 d shorter than those in ordinary herds, respectively (P < 0.05), but no difference was found between the herd groups for the culling interval of unmated sows. For mated sows in the reservice group, culling intervals of high-performing herds were ≥13.7 d shorter than those of the ordinary herds (P < 0.05), but for mated sows in the first service group, there was no difference in the culling interval between the herd groups. The culling hazard from 8 wk postweaning for mated sows in high-performing herds increased more rapidly than that in ordinary herds. In conclusion, to reduce culling intervals and improve herd productivity, we recommend implementing a strict culling policy for mated gilts and mated sows, especially reserviced females.

Factors Affecting Fertility in Loosely Housed Sows and Gilts: Vulvar Discharge Syndrome, Environment and Acute‐phase Proteins

The effect of vulvar discharge syndrome (VDS) on sow and gilt fertility was studied on 26 farms. Of 824 animals inspected in 21 randomly selected and five VDS problem farms, 19 (2.3%) were afflicted with VDS. Altogether 542/799 of the examined animals (67.8%) farrowed thereafter. Nine of the 19 VDS animals (47.4%) and 533/780 non-VDS animals (68.3%) farrowed at the first chance after the examination (p = 0.05). None of the unmated gilts in this study had VDS. Environmental and individual factors likely to be associated with fertility and VDS were tested. In multivariate analysis, factors associated with farrowing were VDS, reproductive status, availability of roughage and confinement to individual stalls. None of the variables tested was associated with VDS. However, all of the VDS problem farms were overcrowded and had concrete, partly slatted floors with little or no bedding. The median value of haptoglobin (Hp) was 2.5 (range 1.3-3.1) g/l in VDS animals and 2.3 (0.5-4.3) g/l in controls (p = 0.6). The median C-reactive protein (CRP) in VDS animals was 30.3 (3.3-171.3) mg/l and in controls 25.9 (3.3-361.1) mg/l (p = 0.7). In conclusion, VDS decreased fertility of gilts and sows in the absence of a systemic acute-phase response, as indicated by stable concentrations of Hp and CRP.

Localization of basic fibroblast growth factor mRNA (FGF-2 mRNA) in the uterus of mated and unmated gilts.

In mated sows, the level of placental vascularization has a direct effect on fetal growth and litter birth weight. Vascularization of the endometrium and uterus under the control of various polypeptide growth factors is an important early stage in this process. Basic fibroblast growth factor (FGF-2), a polypeptide distributed throughout the mesodermal and neuroectodermal tissues of many species, is a vascular endothelial cell mitogen in vitro and has been implicated in neovascularization and wound healing in vivo. As part of our studies of the distribution of FGF-2 in uterine tissue and its role in placental development and embryo implantation, the localization and changes in the abundance of porcine FGF-2 mRNA in the uterus of mated and unmated gilts were investigated by in situ hybridization procedures. These procedures were based on the use of [alpha35S]-dATP-labeled oligonucleotide probes and a novel set of digoxigenin-labeled oligonucleotide probes generated by reverse transcriptase-polymerase chain reaction (RT-PCR) methods and anti-sense labeling strategies from the corresponding mRNA templates. With these in situ hybridization procedures, porcine FGF-2 mRNA was localized during the first 30 days of pregnancy to specific tissue areas in the porcine uterus comprising glandular and luminal epithelial cells and stromal cells of both the stratum functionalis and stratum basalis regions of the endometrium, and within the smooth muscle of myometrium and the associated blood vessels. However, no significant increase in the level of FGF-2 mRNA within these tissues was detected during these early stages of pregnancy or during the estrous cycle of unmated gilts. These distribution and abundance patterns are only partially compatible with other recent observations suggesting a possible role for changing levels of the mature polypeptide form of FGF-2 in the reproductive tract of sows during the early stages of pregnancy.

Maternal recognition of pregnancy in swine. II. Plasma concentrations of progesterone and 13,14-dihydro-15-keto-prostaglandin F2 alpha during the estrous cycle and during short and long pseudopregnancy in gilts.

Two experiments were conducted to determine plasma progesterone (P4) and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) concentrations in unmated gilts induced to have either short pseudopregnancy (SPP) or long pseudopregnancy (LPP). In experiment 1, estradiol-17 beta (E2) was injected on different combinations of days between Days 11 and 16 of the estrous cycle. For gilts induced to exhibit SPP, the interestrous interval averaged 27.0 +/- 0.4 days compared to the control interval of 20.0 +/- 0.4 days. In experiment 2, E2 injections were given on Days 12 and 13 or on Days 12 through 25. Interestrous intervals in SPP and nonpseudopregnant gilts were 25.6 +/- 0.2 and 19.9 +/- 0.6 days, respectively. Four of six gilts treated with E2 on Days 12-25 were induced to have LPP lasting more than 100 days. In both experiments, plasma P4 declined to baseline approximately 3 days before posttreatment estrus, regardless of type of pseudopregnancy induced. Plasma PGFM peaked 4-6 days before posttreatment estrus in gilts displaying each type of response. In gilts exhibiting LPP, plasma PGFM concentrations tended to increase steadily during pseudopregnancy. These data suggest that the mechanisms of luteolysis during the estrous cycle of unmated gilts and during estrogen-induced SPP and LPP may be similar. The present results suggest that luteal persistence during SPP and LPP may be due to delayed peak release of prostaglandin F2 alpha by the uterus.

Effects of transferred ova per recipient and dual use of donors as recipients on production of transgenic swine

The purpose of the study was to determine whether the number of transferred ova per recipient influenced the efficiency of producing transgenic pigs and whether donor gilts were as effective as unmated gilts as recipients of microinjected ova. Eight genes were microinjected into 4,232 ova that were transferred into 169 recipients over a 5-yr period. Although the farrowing rate and litter size was highest for recipients receiving 31 to 41 ova per recipient, the percentage of transferred ova developing into piglets was highest for recipients receiving 13 to 20 ova (P = 0.021 for all recipients and P = 0.011 for pregnant recipients). Based on these data we conclude transferring more than 20 ova per recipient may incur some loss due to uterine crowding. Gilts used as recipients of microinjected ova immediately after their own ova were flushed from their oviducts had the same farrowing rate, litter size, and ovum development efficiency as unmated gilts that were only used as recipients. However, donor-recipients that ovulated 21 or more ova had smaller litters (P = 0.009) and were less efficient in producing pigs (P = 0.024) and transgenic pigs (P = 0.054) from transferred ova than donor-recipients that ovulated 20 or fewer ova. Dual use of donors as recipients was an effective method of reducing the number of recipients in a transgenic pig project by nearly one-half.

Bacterial endometritis and vaginal discharge in the sow: prevalence of different bacterial species and experimental reproduction of the syndrome

Abstract A total of 73 porcine genital tracts were macroscopically and histologically examined and bacteriologically tested for the presence of aerobic facultatively pathogenic bacteria. Nine uteri originated from sows with abnormal vaginal discharge (P-group) and 64 uteri originated from slaughtered sows (S-group). Fifty-six per cent of the uteri from the P-group were bacteriologically positive compared with only 20% of the uteri from the S-group. Uteri of sows with histological evidence of an acute or subacute endometritis were significantly more often infected than the uteri of sows with a chronic endometritis or with histologically normal uteri. The bacteria isolated were mainly Escherichia coli, Staphylococcus spp. and Streptococcus spp. These results indicate that the syndrome of endometritis and vaginal discharge is possibly caused by ascending infections with facultatively pathogenic bacteria. To evaluate the pathogenicity of the isolated bacteria, experimental infections were carried out. Ten pubertal, unmated gilts were inoculated in the uterus by laparotomy with 2 ml of a suspension containing Staphylococcus hyicus , an E. coli sp., an Actinomyces sp. or a carboxyphilic Streptococcus suis sp. An eleventh gilt was inoculated as a control with 2 ml of a phosphate-buffered saline (PBS) solution. The gilts were daily observed for clinical symptoms. Ten to 19 days after inoculation a second laparotomy was carried out to take samples for histological and bacteriological examination. Vaginal discharge was observed in all gilts inoculated with E. coli 10 9 cfu ml −1 or S. hyicus . Clinical signs were not observed in the gilts that were inoculated with the Actinomyces sp., the carboxyphilic Streptococcus suis sp. or 10 7 cfu E. coli . It was possible to reproduce the syndrome of vaginal discharge as it occurs on problem herds, by means of an experimental infection with an E. coli or Staphylococcus hyicus strain. According to Koch's postulates, both inoculated bacteria can be considered as an aetiologic agent of the disease.

Inflammatory response in the pig uterus induced by seminal plasma

The immunological and physiological influence of seminal plasma on the local uterine environment was investigated by immunohistochemical and flow cytometrical studies on uterine tissues and lymph nodes taken from gilts after mating with a vasectomised boar and from control, unmated gilts. These studies revealed that mating with a vasectomised boar induces an acute transient inflammatory response in the endometrium resulting in marked changes in the presence and distribution of leukocytes and extensive proliferation of the endometrial glands. At the same time there was an increase in CD8 L and sIg + cells and an up-regulation of MHC class II and IL-2 receptor expression in the uterine lymph nodes of mated pigs. This would suggest that seminal plasma deposited in the uterus can activate cells in the local draining lymph nodes. Together, these results demonstrate in utero that pronounced immunological and physiological changes are induced in vivo by seminal plasma.

Influence of the oestrous cycle on experimental intrauterine E. coli infection in the sow.

The influence of the oestrous cycle on the onset of endometritis in the sow was studied. Ten pubertal, unmated gilts of the Belgian Negative Landrace were used. Nine gilts were inoculated into the uterus by laparotomy with a suspension of an E. coli strain isolated from the uterus of a discharging sow from a herd having many problems with vaginal discharge and a lowered fertility. One gilt was as a control inoculated with 2 ml of a PBS-solution. All sows inoculated during dioestrus developed clinical symptoms, but only 1 of the 5 gilts inoculated at standing oestrus developed a vaginal discharge. These data confirm the hypothesis that the stage of the oestrous cycle has an important influence on the onset of endometritis. The resistance to E. coli infections was higher when the gilts were inoculated during oestrus.

Effects of electrical stimulation before or after in vitro fertilization on sperm penetration and pronuclear formation of pig oocytes.

The effects of exposure of pig oocytes to an electrical pulse-on sperm penetration and pronuclear formation were determined before or after in vitro fertilization (IVF). After in vitro maturation (IVM) or after collection from oviducts of unmated gilts, pig oocytes either were not exposed or were exposed to an electrical pulse (a 10 sec pulse at 4.0 Vmm-1 AC followed by a 30 microseconds pulse at 120 V mm-1 DC), followed 30 min later by IVF. The incidence of male pronuclear formation of both IVM and in vivo-matured oocytes at 12 hr after insemination was decreased from 59% and 100%, respectively, to 2% and 36%, respectively, by the electrical pulse, but the penetration rates (88-100%) and polyspermic rates (79-100%) were not affected by exposure to an electrical pulse. Similarly, when pig IVM oocytes were exposed to an electrical pulse at 6 hr after insemination, electrical activation did not decrease penetration rates (93% vs. 90%), polyspermic rates (83% vs. 91%), or number of spermatozoa in penetrated oocytes (4.0 +/- 0.5 vs. 4.6 +/- 0.5) but did decrease the rate of male pronuclear formation from 58% to 18%. When oocytes were examined at 6 hr after insemination, 75% of them had been penetrated and resumed meiotic progression, but all sperm heads in penetrated oocytes were fully condensed or only partially decondensed. The percentage of penetrated eggs with multiple female pronuclei was increased when oocytes were exposed to an electrical pulse in all experimental series.(ABSTRACT TRUNCATED AT 250 WORDS)

Endometritis and vaginal discharge in the sow

A clinical study concerning the epidemiology of the syndrome endometritis associated with vaginal discharge and reproductive failure is described. In all affected herds the return rates after service were increased above 30% and the number of weaners per sow per year was decreased by at least two. In an experimental infection model the pathogenicity of Escherichia coli on the sow's endometrium was investigated and the influence of the oestrus cycle on the uterine defence mechanism was studied. Ten pubertal, unmated gilts of the Belgian Negative Landrace were infected in the uterus with suspensions of an E. coli strain isolated from the uterus of a discharging sow. The results indicated that it is possible to induce an acute purulent endometritis by inoculation of E. coli. The stage of the oestrus cycle appeared to be an important factor in the development of endometritis. None of the five gilts inoculated at the day of oestrus with 50 ml of a suspension containing 10 7 cfu ml −1 developed clinical symptoms. Three of the five gilts inoculated just after the end of standing heat also developed clinical signs. The difference between both groups was significant.

The influence of conditions at the time of mating on reproduction of commercial pigs

The objective of this study was to compare a new mating system, called the Detection-Mating Area (DM Area), and a conventional mating system on the long-term reproductive performance of commercial pigs. The DM Area treatment basically involved detecting oestrous females in an arena closely surrounded on two sides by boars and mating these females in this arena. This mating system was designed to improve the physical and sexual environments of the pigs at mating. In contrast, the conventional treatment involved conducting oestrus detection and mating in the boar's accommodation pen. The study was conducted over an 18-month period at a commercial farm that housed 2400 breeding female pigs. In order to control for the effects of the stockperson, an analysis was conducted on the reproductive performance of female pigs in which one stockperson assisted the matings in both treatments over a 12-month period. Gilts mated in the DM Area treatment had a higher ( P<0.05) total litter size and a higher ( P<0.01) litter size born alive than gilts mated in the conventional treatment (10.31 vs. 8.96 and 9.50 vs. 8.29, respectively). Although gilts in the DM Area treatment had a higher farrowing rate (93.2 vs. 87.9%), this difference was not significant ( P>0.05). There were no significant ( P>0.05) differences found between the reproductive performance of sows in the two treatments; however this comparison was confounded by sows in the DM Area treatment having a lower number of matings per oestrus than those in the other treatment. Observations on the sexual behaviour of pigs at 145 matings indicated that the boars in the DM Area treatment displayed a higher ( P<0.05) number of bouts of courting behaviour directed towards the female than boars in the conventional treatment (8.3 and 6.4, respectively). These very limited observations on sexual behaviour suggest that changes in the courting behaviour of bears may be associated with changes in litter size. While there was some indication from the results of progesterone analysis of blood samples taken from unmated gilts that there may have been some differences between treatments in the sexual age of gilts at matings, these differences are unlikely to explain the differences in litter size between treatments. Further research is required to identify the component (s) of the DM Area treatment that are responsible for the improvement in litter size in gilts and to further examine the effects of the two treatments on the reproductive performance of sows.

Use of deuterium-labelled tracers to establish endogenous rates of production and clearance of progesterone during the peri-implantation period in gilts

Using a method based on the constant infusion of a deuterium-labelled tracer, production rates (PR) and metabolic clearance rates (MCR) of progesterone have been determined in gilts between Days 11 and 17 of gestation. This involved the development of a procedure to quantitate the tracer [(7,7,16- 2H 3)-progesterone] in plasma samples, and in the infusate, with the aid of gas chromatography-mass spectrometry. In a group of nine mated gilts, the average (± s.e.m.) progesterone PR was 274 (± 26) μmol/24 h, the average progesterone MCR being 3348 (± 312) 1 24 h . Declining peripheral plasma progesterone levels (PP) between Days 11 and 17 of gestation were associated with increasing progesterone MCR ( P < 0.05), and were not correlated with increasing PR. For comparison, progesterone PRs and MCRs were determined in five unmated gilts between Days 11 and 15 of oestrus, prior to the normal onset of luteolysis. The mean progesterone MCR in these animals (2735±275 1 24 h ) was similar to the respective pregnancy mean ( P > 0.1), but the PR (158±12 μmol/24 h) was lower ( P < 0.01). PP values, PR values and numbers of corpora lutea were not significantly correlated ( P > 0.1) in either mated or unmated groups of gilts. The results of this study support previous indications of luteotrophic effects of conceptus tissues after Day 10 of pregnancy in the sow, and provide quantitative bases for progesterone replacement in ovariectomized pigs between Days 11 and 17 after oestrus/coitus.

The incidence of, and factors associated with, failure to mate by 245 days of age in the gilt

The incidence of, and factors associated with, gilts failing to mate between 29 and 35 weeks of age were studied over 12 months at a large intensive piggery in southern Australia. After excluding gilts culled as physically unsound, 10.5% of the remaining 2484 gilts failed to mate and were slaughtered. Seventy percent of unmated gilts had ovulated, and of these, 54% had shown negative or low responses to the back-pressure test (BPT) and 16% had shown moderate or high responses. Few prepubertal gilts (1%) had abnormal reproductive tracts. When group size was greater than 50 gilts (< 0.9 m 2/gilt) immediately prior to mating (27–28 weeks of age), there was a higher incidence of unmated gilts and an increase in the proportion of unmated gilts which had shown negative or low BPT response than when groups were less than 50 gilts (12.9 vs. 8.6%, P < 0.001; and 8.0 vs. 3.6%, P < 0.001, respectively). The incidence of prepubertal gilts at 35 weeks was lower during spring than other seasons (1.48 and 3.36%, P < 0.05) and higher during summer than other seasons (4.61 and 2.37%, P < 0.01). Fewer Large White gilts remained unmated at 35 weeks of age than Landrace or Large White-Landrace synthetic breed gilts (7.7 and 14.1% of those selected, P < 0.001). More purebred gilts were prepubertal at 35 weeks of age than crossbred gilts (5.4 and 2.4%, P < 0.01).

Reproductive performance, growth and carcass characteristics of gilts mated at puberty, restricted in food intake during gestation and slaughtered post-partum

ABSTRACTSeventy-four Yorkshire gilts, mated at puberty, were used in three experiments to study the effect of severe food restriction, 0·45 kg/day for either the last 15 or 30 days of gestation, on reproductive performance, body-weight change, and carcass quality and meat acceptability. The objective of the experiments was to assess the feasibility of limiting weight gain during gestation to produce an acceptable carcass post-partum, within the market weight range of 55 to 90 kg. Age and weight at puberty averaged 170·3 days and 99·1 kg respectively. Litter size averaged 9·3 liveborn piglets at an average weight of 1·13 kg. The necessary reduction in weight gain during gestation to bring final carcass weight within the acceptable range was associated with a significant reduction in mean individual birth weight to below 1·0 kg. Sensory evaluation of loin and ham joints from mated and unmated gilts of market weight revealed no differences in juiciness or flavour but both loin and ham joints from maiden gilts were significantly more tender than those from gilts that had farrowed and from unmated controls of the same age as those that had farrowed

Transfer of preimplantation pig embryos following in vitro culture for 24 or 48 hours.

Two experiments were conducted to determine the viability of 258 pig ova cultured in vitro for 24 or 48 hr by transfer to 19 recipient gilts. One- to four-cell ova were recovered from donor gilts and cultured in droplets of Brinster's medium under oil. A humidified gas mixture of 5% CO2 and 95% air flowed through the incubator which was maintained at 37 C. In Experiment I, a total of 69 ova was transferred to six unmated gilts after a 24 hr in vitro culture period. At recovery, 63 ova were at the two-cell stage, and at transfer 59 were at the four-cell stage. Five of six (83%) recipient gilts had an average of 7.6 (63%) normal embryos at slaughter on days 26 to 33 post-estrus. In Experiment II, a total of 189 ova were transferred to 13 unmated gilts following a 48 hr in vitro culture period. Fifty-three percent of the ova were recovered at the two-cell stage and the remainder were recovered either as one-(21%) or four-cell (26%) ova. After 48 hr in culture 77% of the ova were transferred at the four- or six-cell stage of development. Two gilts (15%) were pregnant and slaughtered 28 and 34 days post-estrus. Fifteen of 29 (52%) ova transferred to the two pregnant recipients were present as normal embryos. The reduced pregnancy rate in Experiment II may have been due to factors other than the increased length of the culture period. During the course of Experiment I, 12 of 28 ova maintained in culture from the same donors as those which were transferred developed to the blastocyst stage after 96 to 120 hr in culture. None of the 97 ova cultured for 72 additional hr after Experiment II ova were transferred reached the blastocyst stage.

Meat production from pigs which have farrowed. 2. Carcass characteristics

SUMMARYThe carcass characteristics of young adult female pigs (gilts) slaughtered after weaning their first litters have been investigated using three groups of 19 Landrace × (Landrace×Large White) gilts. In two treatment groups gilts were mated at their pubertal oestrus and suckled their piglets for 5 to 11 and 35 to 42 days respectively. These gilts were slaughtered on average 10 days after weaning. A third control group consisted of unmated gilts slaughtered at 118 kg live weight.There was no significant difference in the killing-out percentage for the three groups. The carcasses of the gilts which farrowed contained significantly less fat (P&lt;0·001) than those of the unmated controls. The carcasses of the farrowed gilts had significantly lighter middle sections (P&lt;0·001) and significantly heavier shoulders (P&lt;0·001) than the controls.Despite the variations in tissue yield and distribution, the yield of prime joints for the gilts which had farrowed was only 0·62 percentage units less than that of the controls.No commercially significant variations between groups in meat quality were observed.

Meat production from pigs which have farrowed 1. Reproductive performance and food conversion efficiency

SUMMARYThe reproductive performance and food conversion efficiency ofyoung female pigs (gilts) destined for slaughter after weaning their first litter were investigated using four treatment groups of 19 Landrace × (Landrace × Large White) gilts. In two treatment groups gilts were mated at pubertal heat and suckled for 5 to 11 and 35 to 42 days respectively. These gilts were slaughtered following weaning. A third group of gilts were conventionally mated at third oestrus and suckled for 35 to 42 days. These animals acted as controls for reproductive performace. The fourth treatment group consisted of unmated gilts, slaughtered at 118 kg live weight, which served as controls for food conversion efficiency, growth rate and carcass measurements.There were no significant differences in either the number or weight of piglets born in any of the treatment groups. The food conversion efficiency and growth rate of the mated gilts was significantly (P&lt; 0·001) worse than that of the unmated gilts marketed at heavy weights. Of the mated gilts those mated at puberty and weaned at 35 to 42 days had the best overall feed conversion efficiency (4·56: 1) between the start of the experiment and weaning and required less food per piglet reared to 6 weeks of age than the gilts mated at third heat.