Piglet Birth Weight Research Articles

Efecto del número de parto de la cerda, la caseta de parición, el tamaño de la camada y el peso al nacer en las principales causas de mortalidad en lechones

Effects of litter size, farrowing room, individual birth weight and parity number on piglet mortality at farrowing were assessed. A total of 1,374 farrowing sows were evaluated for nine months. Sow parity number (SPN), birth date (BD), litter size (LS), live-born piglets (LBP), stillbirths (S), average individual piglet birth weight (PBW), farrowing facilities (FF), weaned piglets (WP), weaning weight (WW), preweaning mortality (PM) and cause and age of death were recorded. SPN was grouped from first to seventh parity. LS was ranked as follows, <=,,,8, 9, 10, 11, 12 and ≥,,,13 piglets. PBW was ranked as follows, <=,,,1.26, 1.27 to 1.40, 1.41 to 1.56, and ≥,,,1.57 kg. Effect of SPN on LS, LBP, S and WP was found (P<0.01), as well as of FF on LBP, S and WP (P<0.01). Mortality was due mainly to crushing (37.0 %), sacrifice (13.6 %) and low weight (12.8%). Difference (P<0.05) for SPN and low weight at birth was found, and difference (P<0.05) for FF effect on mortality due to crushing, low weight, sacrificed and other causes was found too. Differences (P<0.01) due to LS for low weight at birth and starvation were found. It can be concluded that piglet mortality is due mainly to litter size and farrowing facilities.

Effect of Milk Formula Protein Content on Intestinal Barrier Function in a Porcine Model of LBW Neonates

Our study aimed at investigating the impact of the level of protein in milk formula on intestinal structure, barrier function, and its nervous regulation in normal and LBW neonates using a porcine model. Normal birth weight (NBW) or LBW piglets were fed from d7 to d28 of age either with a high protein (HP) or with an adequate protein (AP) formula or stayed with their mother [mother fed (MF)]. The proximal jejunum and distal ileum were sampled at d28 for morphometry analysis and ex vivo permeability measurement in Ussing chambers. Formula feeding induced a trophic effect on the jejunum and ileum of both NBW and LBW piglets, which exhibited longer villi than MF animals, irrespective of the type of formula. In NBW piglets, intestinal permeability was not altered by formula feeding. On the contrary, LBW piglets fed with HP formula, but not AP, exhibited a greater ileal permeability than MF piglets. Feeding the HP formula also disturbed jejunal and ileal regulation of permeability by acetylcholine and vasoactive intestinal peptide (VIP) in LBW compared with MF LBW piglets. In conclusion, the level of protein in formulas did not modify intestinal structure and function in NBW individuals but dramatically modified intestinal barrier function physiology in LBW individuals.

Colostrum production by sows: variability of colostrum yield and immunoglobulin G concentrations

Colostrum provides newborn piglets with energy, immunoglobulins and growth, thereby playing an essential role in piglet survival. However, colostrum yield and composition are highly variable among sows. Some of the factors involved in this variability have been identified. The aim of the study was to confirm previous findings on a large number of animals and to investigate other potential factors of variation, such as the process of farrowing and the morphological changes of the mammary epithelium that occur during the 24 h post partum. The experiment was conducted on 16 Large White (LW) and 56 Landrace (LR) × Large White (LR × LW) crossbred sows of mixed parities and their litters. Most farrowings were induced at 113 days of gestation and all farrowings were attended. Each piglet was weighed at birth and 24 h after farrowing started (t24). Colostrum ingestion by individual piglets was estimated using piglet weight gains from birth to t24. Colostrum production by sows was estimated by summing up colostrum intakes by each piglet of the litter. Colostrum was collected at the onset of farrowing (t0) and at t24 to determine concentrations of immunoglobulins G (IgG), Na and K. Analyses of correlations and multiple regressions were performed to identify the variables involved in variation of colostrum yield and IgG concentrations. Colostrum yield was not related to litter size and weight (P > 0.1). It was negatively correlated with the number of stillborn piglets (r = −0.33, P = 0.005) and within-litter variation of piglet birth weight (r = −0.24, P = 0.04). It was not related to the Na/K ratio in the colostrum, which is an indicator of the integrity of the mammary epithelium. When sows were categorised according to their level of colostrum yield, sows that produced a low yield of colostrum had more stillborn piglets at birth than the other sows (P < 0.05) and tended to have a longer birth interval during the early process of parturition (P < 0.1). At t24, concentrations of IgG in the colostrum were positively correlated with the Na/K ratio in the colostrum (r = 0.53, P < 0.001), which indicates the concomitance of the cessation of IgG transfer to the colostrum and the changes in the morphology of the mammary epithelium. This study points out the need for future research on the role of the hormones involved in both the process of parturition and lactogenesis in the relationship between stillbirth, process of parturition and colostrum production.

Effects of seasonality and ambient temperature on genetic parameters for production and reproductive traits in pigs

This study examined the effects of season on genetic parameters for production and reproductive traits and quantified within contemporary group effects of temperature on these traits using linear and plateau-linear regression models. From 2003 onwards, data were available on ~60 000 gilts for the routinely recorded production traits (BF: back fat; LADG: lifetime average daily gain) and ~45 000 litters for the sow reproductive traits (TB: total born; NBA: number born alive; BWT: average piglet birthweight). A subset of gilts were also recorded for test period daily gain (TADG), daily feed intake (ADI) and feed conversion ratio (FCR) and, later, as sows (n ~2000) for average daily lactation feed intake (LADI). Least-squares means for some production and reproductive traits significantly differed between seasons: summer and winter means were 2.28 ± 0.017 vs 2.54 ± 0.011 kg/day for ADI, 2.80 ± 0.022 vs 3.21 ± 0.011 kg/kg for FCR, and 1.61 ± 0.02 vs 1.54 ± 0.02 kg for BWT. However, some statistically significant differences (due to large n) were biologically insignificant. Trait variation also differed between seasons, but heritability estimates did not significantly differ from each other. Heritabilities were (summer vs winter): BF: 0.43 ± 0.03 vs 0.41 ± 0.02; LADG: 0.18 ± 0.02 vs 0.16 ± 0.02; TADG: 0.12 ± 0.10 vs 0.08 ± 0.06; ADI: 0.37 ± 0.15 vs 0.22 ± 0.07; FCR: 0.14 ± 0.11 vs 0.17 ± 0.06; TB: 0.09 ± 0.01 vs 0.10 ± 0.01; NBA: 0.06 ± 0.01 vs 0.07 ± 0.01 and BWT: 0.37 ± 0.03 vs 0.32 ± 0.04. Genetic correlations between the same trait recorded in different seasons were generally very high (&gt;0.70), with the exception of TB, where the genetic correlation between spring and autumn was 0.65 ± 0.09, suggesting a genetic component to the effect of seasonal infertility on litter size. Regression models demonstrated that two selection lines had different responses to increasing temperature, despite concurrent selection in the same environment. Plateau-linear models were generally better than linear models for describing changes to production traits with temperature. Based on maximum temperature at the end of performance testing, the estimated temperature thresholds above which lifetime growth performance was compromised were 25.5 and 32.5°C in the two lines. There were only small linear relationships between reproductive traits and temperature. Overall, the ongoing acclimatisation to the thermal environment and the partial confounding of contemporary group with temperature variables (season explained 62% of variation in average daily temperature) are potentially contributing factors to the lack of major differences in heritability estimates between seasons, and the relatively small regression coefficients for the effects of temperature on performance. Nevertheless, temperature can be demonstrated to affect phenotypic outcomes within contemporary groups using commercial data.

148 PIGLET GROWTH AND BLOOD COMPONENTS DURING LACTATION FOLLOWING RECIPROCAL EMBRYO TRANSFER BETWEEN MEISHAN AND WHITE CROSSBRED GILTS

Sow productivity has a significant economic impact on the swine industry and is influenced by several factors, including preweaning piglet mortality. In Western breeds, low birth weight piglets exhibit the greatest susceptibility to preweaning mortality. In contrast, Meishan (MS) piglets have decreased birth weights but lower preweaning mortality rates, suggesting that birth weight is not the sole component of preweaning survival. The objective of the current study was to determine the contributions of the maternal and piglet breed and their interactions on piglet growth and blood components pertaining to survivability during lactation following reciprocal embryo transfer between MS and White crossbred (WC) gilts. Twenty-five successful pregnancies were produced by embryo transfer in 2 farrowing seasons that represented all maternal and piglet breed combinations; MS × MS (n = 4 litters), MS × WC (n = 7 litters), WC × MS (n = 7 litters), and WC × WC (n = 7 litters). At Day 1, 10, and weaning (average weaning age = 18 days), piglets (n = 147, 97, and 94, respectively at Day 1, 10, and weaning) were weighed and blood samples were taken. Hematocrit, hemoglobin, glucose, nitrogen, nonesterified fatty acids, albumin, and cortisol were measured in all blood samples. All data were analysed for ANOVA using mixed model procedures. Piglet weights were greater (P &lt; 0.001) throughout lactation in piglets from WC dams regardless of piglet breed. As a result, average daily gains from Days 1 to 10 and weaning were greater (P &lt; 0.05) in piglets from WC dams. There were significant (P &lt; 0.001) maternal × piglet × day interactions for hematocrit and hemoglobin levels in which levels were greatest at Day 1 in MS piglets from WC dams and at Day 10 in MS piglets from MS dams but decreased in WC piglets from WC dams at Day 1. Glucose was greater (P &lt; 0.05) at Day 1 in piglets from WC dams regardless of piglet breed but was greater (P &lt; 0.05) at weaning in WC piglets regardless of maternal breed. Nitrogen was similar at Day 1 for all maternal and piglet breed combinations, but at Day 10 and weaning, nitrogen levels were greater (P &lt; 0.001) in MS piglets regardless of maternal breed. Nonesterified fatty acid was greater throughout lactation in piglets from MS dams irrespective of piglet breed. Albumin was greater (P &lt; 0.05) in MS piglets throughout lactation regardless of maternal breed. Cortisol was not different between the maternal and piglet breed combinations throughout lactation, but cortisol was greater (P &lt; 0.001) at Day 1 compared with Day 10 and weaning. This study demonstrated that piglet growth during lactation was influenced more by maternal breed in favor of WC dams, which supports previous crossbreeding studies. However, blood components pertaining to survivability displayed complex interactions between the piglet and maternal breed, which may signify possible mechanisms for improved preweaning survivability of MS pigs.

Effects of extra feeding in mid-pregnancy for three successive parities on lean sows’ productive performance and longevity

The aim of this study was to investigate the long-term effects of increasing feeding allowance during mid-pregnancy in sows. A total of 103 PIC pregnant sows (mixed parity) were allocated to two treatments: control (C, n = 49) were fed 2.5-3.0 kg d-1 (12.1 MJ ME kg-1) and extra-fed (E, n = 54) received +2.0 kg d-1 of the same feed from day 45 to 85 of gestation over three consecutive cycles. Body weight, backfat thickness (BF) and loin depth were measured on days 45 and 85 of gestation, farrowing and weaning. Litter and sows performance were recorded during lactation and post-weaning. Overall culling rates were 61 and 67% for C and E groups, respectively. After three cycles, E sows showed a positive BF balance in contrast to C sows (E = +1.46 mm and C= -1.81 mm, P &lt; 0.05). In cycle 3, E sows presented greater piglet birth weights than C sows, being mainly evident in sows that were nulliparous at the onset of the experiment (P &lt; 0.05). Extra-fed sows showed a greater incidence of mastitis-metritis-agalactia syndrome than C sows (P = 0.003). Thus, increasing feeding allowance during mid-pregnancy positively affected BF balance and birth weight in nulliparous, but impaired the sows’ ability to produce milk in the long-term.

Statistical tools to detect genetic variation for a sex dimorphism in piglet birth weight1

Sex differences in birth weight contribute to within-litter variability, which itself is connected to piglet survival. Therefore, we studied whether the sex difference in piglet birth weight is a genetically variable sex dimorphism. For that purpose a linear mixed model including sex-specific additive genetic effects was set up. A hypothesis testing problem was defined to detect whether these genetic effects significantly differ between sexes. In a second step, the effect of sex-linked genes was studied explicitly by partitioning the additive genetic effects into autosomal and gonosomal effects. Furthermore, a definition of heritability for the sex difference of a randomly chosen pair of littermates with opposite sex was given. The proposed models were applied separately to a Landrace and Large White data set. Significant genetic variability for the sex dimorphism was found in Landrace (P = 0.03) but not in Large White (P = 0.10). Heritability estimates were at 3 to 5% depending on the model. The X-chromosomal genetic variation was not significant (P > 0.18) at all, whereas the Y-chromosome significantly (P < 0.01) contributed to the genetic variation in Landrace with a corresponding SD of 34 g. It can be concluded that the sex dimorphism of piglet birth weight is genetically variable and a potential target of genetic improvement.

Expression profiling of IGFs and IGF receptors in piglets with intrauterine growth restriction

In order to test the hypothesis that expression levels of insulin-like growth factor system is altered in piglets with intrauterine growth restriction (IUGR), the present study was conducted to compare the expression levels of IGF-I, IGF-II, IGFR1, IGFR2 and IGFBP5 in m. longissimus, liver and kidney in 21-day-old IUGR piglets with normal birth weight (NBW) piglets. Our results showed that the expression level of insulin-like growth factor 1 was significantly lower ( p < 0.05) in m. longissimus, liver and kidney of the IUGR piglets compared with the NBW piglets. However, there were no differences in the expression levels of IGF2, IGF1R, IGF2R and IGFBP5 in all tissues tested between NBW and IUGR piglets.

Analysis of birth weight variability in pigs with respect to liveborn and total born offspring

Reduction in the variability of piglet birth weight within litter and increased piglet survival are key objective in schemes aiming to improve sow prolificacy. In previous studies, variation in birth weight was described by the sample standard deviation of birth weights within one litter, and the genetic impact has been proved. In this study, we additionally considered the sex effect on piglet's birth weight and on its variability. The sample variance of birth weights per litter separated by sex was assigned as a trait of the sow. Different transformations of the trait were fitted by linear and generalized linear mixed models. Based on 1111 litters from Landrace sows, the estimates of heritability for the different measures ranged from 11 to 12%. We analysed the influence of including birth weight of stillborn piglets on the variability of birth weight within litter. With omitted stillborns, the heritability was estimated approximately 2% higher than that in investigations of all born piglets, and the impact of sex on birth weight variability was increased. Because the proportion of intrapartum deaths is rather high, it is recommended to consider the total number of piglets born per litter when analysing birth weight variation.

Genetic parameters for piglet survival, litter size and birth weight or its variation within litter in sire and dam lines using Bayesian analysis

Genetic parameters for survival at birth, litter size, birth weight and its variation within litter have been estimated in dam (D1, D2 and D3) and sire lines (S1 and S2) and genetic associations among these traits were examined. Genetic parameters, calculated as posterior means, were estimated at piglet (D1 and D2; 23,565 piglets) and litter level (all lines; 3497 litters) using a Bayesian approach. Posterior means of heritabilities for survival at piglet level (SVBP) were consistently low at 0.01, 0.06 to 0.07 and 0.04 to 0.06 for direct ( h 2 d), maternal ( h 2 m) and total ( h 2 t) genetic effects, respectively, with positive posterior means of correlations between the direct and maternal effect ( r g-dm). For survival at litter level (SVBL) heritabilities were between 0.05 and 0.20, with highest estimates in lines with lowest birth weight. For individual piglet birth weight (IBW) heritabilities were substantially higher than for SVBP, ranging from 0.13 to 0.19 ( h 2 d), 0.16 to 0.28 ( h 2 m) and 0.08 to 0.28 ( h 2 t). Heritabilities for average litter birth weight (ALBW) ranged from 0.23 to 0.34, while heritabilities for variation of birth weight within litter (STD) ranged from 0.10 to 0.27. Heritabilities for number born in total (NBT) ranged from 0.11 to 0.16. Genetic associations between SVBL and NBT varied from favourable at 0.39 (D1) to unfavourable at − 0.22 (D2). Genetic correlations of SVBL with ALBW and STD were mostly favourable (0.22 to 0.55 and − 0.18 to − 0.52, respectively) except for SVBL-ALBW in D1 (− 0.50) and SVBL–STD in S2 (0.48). In D1 favourable genetic correlations were estimated between direct or maternal effects of SVBP and IBW whereas those for D2 were unfavourable. Consistently negative correlations were estimated between direct effects of SVBP and maternal effects of IBW. Adjustment for NBT resulted in slightly higher h 2 d and h 2 m for SVBP, with unfavourable r g-dm. Selection for survival is expected to be successful because all lines showed considerable variation for this trait and relatively high heritabilities, in particular in lines with low ALBW. Maternal heritabilities of IBW were mostly at moderate magnitude and thus of interest for selection. For most lines, the correlations between traits indicate that selection on either IBW or ALBW is indirectly increasing survival at birth. The variation in heritabilities among lines indicates that the strategy of selection for an optimal birth weight with lowest variation within litter should be considered per line individually to maximise overall genetic improvement in piglet survival and growth.

Impact of porcine epidemic diarrhea virus infection at different periods of pregnancy on subsequent reproductive performance in gilts and sows

Reproductive performance of gilts and sows in a swine commercial herd following an outbreak of porcine epidemic diarrhea virus (PEDV) were investigated. A PEDV outbreak was observed in March 2008 in a swine herd in Thailand. The disease was diagnosed by clinical symptoms, gross and histopathology and viral detection using reverse transcriptase-polymerase chain reaction assay. The intestines of the infected piglets were collected, minced and fed to all of the gilts and sows within 2 weeks after the onset of the PEDV outbreak. Reproductive data were collected during a period from January 2007 to July 2008 and were retrospectively evaluated. The farrowing rate (FR), return rate (RR), abortion rate (AR), number of total piglets born per litter (TB), number of piglets born alive per litter (BA), percentage of stillbirth piglets per litter (SB), percentage of mummified fetus per litter (MM) and piglet's birth weight (BW), before and after the PEDV outbreak were compared. It was found that the impact of PEDV infection on the reproductive performance of gilts and sows depended on the period of pregnancy when the females were exposed to the pathogen, and parity number. The pregnant females infected with PEDV during the first 30 days of pregnancy had a 12.6 percentage point decrease of FR (91.1% vs. 78.5%, P = 0.003), a 5.7 percentage point increase of RR (3.5% vs. 9.2%, P = 0.01), a 1.3 percentage point increase of AR (2.1% vs. 3.4%, P = 0.01) and a 2.0 percentage point increase of MM (3.5% vs. 5.6%, P < 0.001). SB increased in the pregnant females that were infected with PEDV during 91–120 days of pregnancy (1.8 percentage points, 4.5% vs. 6.2%, P = 0.01). The impacts of PEDV infection on subsequent reproductive performance were more severe in the pregnant gilts than the pregnant sows. PEDV infection during the first 30 days of pregnancy resulted in a decrease of TB by 1.4 (11.7 vs. 10.3 piglets/litter, P < 0.001) and a decrease of BA by 2.2 (10.7 vs. 8.5 piglets/litter, P < 0.001) in the gilts’ litters, while the influence of PEDV infection on TB and BA was not significant in sows ( P > 0.05). It was concluded that natural infection of PEDV in the pregnant gilts and sows caused a reduction of subsequent reproductive performance.

Absorption of orally supplied immunoglobulins in neonatal piglets

Low birth weight piglets have a reduced viability because of a low colostrum immunoglobulin (Ig) and energy intake. Additional supply of energy and Ig may improve their survival and immuno-competence. This study was conducted to determine the absorption of IgG from oral supplements containing IgG from porcine plasma and an additional energy substrate, as compared to IgG absorption from sow colostrum. Sixty newborn piglets (mean body weight (BW) 1183 g) from eight sows were removed from the dam prior to suckling and allocated to five treatments. Piglets received either 28 g of standardised sows colostrum per kg of BW (control) or one out of four products containing porcine IgG and fats, glycerine, dextrose or a combination of these as additional energy source. After 12 h of fasting in which only drinking water was supplied, plasma IgG content was determined and efficiency of IgG absorption calculated as total plasma IgG divided by ingested IgG. Treatment means of plasma IgG varied from 1.8 to 7.3 mg/mL (P < 0.001), being 6.8 mg/mL for control piglets. Relative efficiency of absorption varied from 0.05 to 0.28 (P < 0.001), being 0.20 for control piglets. These results indicate that the energy component of the supplements had a major influence on the IgG absorption. IgG absorption from products based on dextrose, medium chain and vegetable long chain triglycerides was similar or higher than IgG absorption from sow colostrum, thus allowing perspective for the development of supplements to improve viability of neonatal piglets.

Effect of piglet birth weight on survival and quality of commercial market swine

The objective of this study was to determine the effect of individual piglet birth weight on mortality and pig quality in a U.S. commercial production system. Pigs used in this study were farrowed from Large White × Landrace sows ( n = 463) bred to Duroc boars during a 4 week period at a commercial sow farm. Within 24 h of birth, all pigs (born alive = 5727 and stillborns = 513) were weighed and individually indentified. A portion of pigs (16.7%) were cross-fostered to reduce litter size variation during lactation. Individual mortality was recorded daily during the suckling phase. Pigs were weighed 2 days prior to weaning (18.7 ± 2.1 days of age), finisher placement (74.8 ± 1.9 days of age), and 16 weeks into finishing (172.8 ± 1.8 days of age). During BW collections, an inventory of all live pigs was conducted, and pigs were given a quality score based on visual evaluation of BW and health (3 = healthy pig; 2 = slightly small and/or slightly unthrifty; 1 small and/or unthrifty). Survival was analyzed for 4 distinct time periods (prenatal, pre-weaning, nursery phase, and finishing phase). Data were analyzed using a logit (survival) or cumulative logit (quality score) function. Birth weight linear effects on prenatal, pre-weaning, and nursery survival as observed mortality probability increased as birth weight decreased. However birth weight did not impact the likelihood of survival during finishing. As birth weight decreased, the likelihood of pigs being poorer quality, quality score (1 or 2), at weaning, finisher placement, and 16 weeks into finishing, increased. As birth weight increased the likelihood of a pig being full value at the end of the finishing phase increased. Reduced individual piglet birth weight, was associated with reduced pig quality and likelihood of prenatal, pre-weaning, and nursery survival. Because of the negative impact of birth weight on pre-weaning and nursery survival and pig quality in finishing, as birth weight decreased pigs were less likely to be full value at harvest.

Reproductive performance of gilts according to growth rate and backfat thickness at mating

The study evaluated the influence of growth rate (GR) and backfat thickness (BF), at first mating of gilts, on the reproductive performance until the first farrowing and on the variation in birth weight of piglets. Gilts were categorized into three groups according to GR from birth until the first mating: GRI (600–700 g/d; n = 345), GRII (701–770 g/d; n = 710) and GRIII (771–870 g/d; n = 366). Analyses were also performed considering three groups formed according to BF (mm) at mating: BFI (10–15 mm; n = 405); BFII (16–17 mm; n = 649) and BFIII (18–23 mm; n = 367). There were no differences in farrowing rate and return to estrus rate among BF or GR groups ( P > 0.05). GRII and GRIII females had larger litter size compared to GRI gilts ( P < 0.05), respectively, 0.5 and 0.9 more piglets, but a greater percentage of intra-partum stillborns ( P < 0.05) was observed in GRIII than in GRI and GRII females. Moreover GRIII females had more piglets ( P < 0.05) weighing less than 1,200 g, litters with a greater coefficient of variation for birth weight and a greater percentage of litters with a coefficient of variation above 20% ( P < 0.05) than GRI females. More total born and born alive piglets were observed in BFII compared with BFI females ( P < 0.05). There were no differences among BF groups in number of stillborn neither in variables concerning the birth weight of piglets ( P > 0.05). These results show that there is no advantage, in terms of farrowing rate and number of born alive, in performing the first mating of gilts with GR > 770 g/d and BF > 17 mm.

Impact of piglet birth weight, birth order, and litter size on subsequent growth performance, carcass quality, muscle composition, and eating quality of pork1

The objective of this study was to investigate the relationships among birth weight, birth order, or litter size on growth performance, carcass quality, and eating quality of the ultimate pork product. Data were collected from 98 pig litters and, with the addition of recording birth weight and birth order, farrowing and piglet management were according to normal barn practices. In the nursery and during growout, the pigs received the normal feeding program for the barn and, with the addition of individual tattooing, were marketed as per standard procedure. From 24 litters, selected because they had at least 12 pigs born alive and represented a range of birth weights, 4 piglets were chosen (for a total of 96 piglets) and sent to Agriculture and Agri-Food Canada-Lacombe Research Centre (Lacombe, Alberta, Canada) when they reached 120 kg for extensive meat quality and sensory analysis. Individual BW was measured at birth, on the day of weaning, 5 wk after weaning, at nursery exit, at first pull, and at the time of marketing. Litter sizes were divided into 3 categories: small (3 to 10 piglets), medium (11 to 13 piglets), and large (14 to 19 piglets). There were 4 birth-weight quartiles: 0.80 to 1.20, 1.25 to 1.45, 1.50 to 1.70, and 1.75 to 2.50 kg. Increased litter size resulted in reduced mean birth weight (P < 0.05), but had no effect on within litter variability or carcass quality (P > 0.05) when slaughtered at the same endpoint. Lighter birth-weight pigs had reduced BW at weaning, 5 and 7 wk postweaning, and at first pull and had increased days to market (P < 0.05). Birth weight had limited effects on carcass quality, weight of primal cuts, objective quality, and overall palatability of the meat at the same slaughter weight (P > 0.05). In conclusion, increased litter size resulted in decreased mean birth weight but no change in days to market. Lighter birth-weight pigs took longer to reach market. Despite some differences in histological properties, birth weight had limited effects on carcass composition or final eating quality of the pork when slaughtered at the same BW and large litter size resulted in more pigs weaned and marketed compared with the smaller litters. We concluded that based on the conditions of this study, other than increased days to market, there is no reason based on pig performance or pork quality to slow down the goal of the pork industry to increase sow productivity as a means to increase efficiency.

Effect of feeding starter mixed feed to suckling pigs on their reproductive qualities

Feeding starter mixed feed to piglets from age 7 to 60 days reduced the age of the first mating and number of unfertilized replacement gilts, increased the number of piglets born alive and piglet birth weight, increased the volume of ejaculate and sperm number of boars, and reduced the number of pathological and immature sperm.

316. MATERNAL DIETARY ARGININE SUPPLEMENTATION DURING LATE GESTATION IMPROVES REPRODUCTIVE EFFICIENCY IN PIGS

Arginine (a non-essential amino acid) and its conversion to nitric oxide (NO) can promote formation of new blood vessels and cause vasodilation. This may reduce resistance and increase blood flow to the uterus and placenta, and the delivery of nutrients for fetal growth and survival. In pregnant rats, dietary arginine deficiency causes IUGR and increases fetal death and perinatal mortality, whereas dietary arginine supplementation reverses this. Human IUGR is associated with impaired NO synthesis, and eNOS activity in umbilical vein endothelial cells, but maternal arginine supplements have produced inconclusive results. We hypothesised that maternal arginine supplementation (MAS) in the pig (a species with naturally occurring IUGR), during late gestation, when placental angiogenesis and vascularity increase, would increase birth and placental weights. Large White (LW) and Landrace (LR) gilts (n = 285) and sows (n = 326), were fed either a control or arginine supplemented (+25 g/d arginine, Nutreco Progenos premix) diet (2.5 kg/d) in late gestation (d75-term at ~114 days). Number born, born alive, still born and mummified, birth weight and d10 weight of progeny were measured. Data were analysed using Univariate ANOVA. MAS in late gestation in gilts and sows reduced the number of still born (Con: 1.17 ± 0.13 piglets/litter; Arg: 0.84 ± 0.09 piglets/litter; P = 0.046). In LW gilts, MAS increased birth weight (Con: 1.21 ± 0.05kg; Arg: 1.34 ± 0.05kg; P &lt; 0.05), and litter birth weight (Con: 13.38 ± 0.72 kg; Arg: 15.27 ± 0.73 kg; P &lt; 0.05). MAS also increased birth weight in LW (Con: 1.17 ± 0.06 kg; Arg: 1.30 ± 0.06 kg; P &lt; 0.05) and LR (Con: 1.47 ± 0.05 kg; Arg: 1.60 ± 0.05 kg; P &lt; 0.05) sows, and reduced still borns in LW sows (Con: 1.12 ± 0.14 piglets/litter; Arg: 0.77 ± 0.09 piglets/litter; P &lt; 0.05). MAS in late gestation improves pregnancy outcomes in terms of piglet survival and birth weight, in LW and LR gilts and sows. MAS during critical periods of placental development may enhance placental-fetal blood flow and nutrient transfer, thereby improving fetal growth and survival.

Effect of piglet birth weight on serum triglyceride levels at weaning and at slaughter

Effect of piglet birth weight on serum triglyceride levels at weaning and at slaughter

Maternal responses to daily maternal porcine somatotropin injections during early-mid pregnancy or early-late pregnancy in sows and gilts1

Piglet neonatal survival and postnatal growth and efficiency are positively related to birth weight. In gilts, daily maternal porcine ST (pST) injections from d 25 to 100 (term approximately 115 d), but not d 25 to 50, of pregnancy increase progeny birth weight. Daily maternal pST injections from d 25 to 50 increase fetal weight at d 50 in gilts and sows. We therefore hypothesized that daily pST injections from d 25 to 100, but not d 25 to 50, of pregnancy would increase birth weight similarly in both parities. Landrace x Large White gilts and sows were uninjected (controls) or were injected daily with pST (gilts: 2.5 mg/d; sows: 4.0 mg/d, each approximately 15 microg of pST/kg per day) from d 25 to 50 or 100 of pregnancy. Litter size and BW were recorded at birth, midlactation, and weaning. Dams were followed through the subsequent mating and pregnancy. Maternal pST injections from d 25 to 100, but not d 25 to 50, increased mean piglet birth weight by 11.6% in sows (P <or= 0.001) and by 5.6% in gilts (P = 0.008). Both pST treatments decreased litter size by approximately 0.6 live-born piglets (each P <or= 0.025). In sows, maternal pST treatment from d 25 to 100 increased culls at weaning (P = 0.037). In remated dams, prior treatments did not affect (P > 0.1) the weaning-remating interval, conception rate, or subsequent litter size. Greater pST-induced birth weight increases in sows than in gilts may mean that underlying metabolic or placental mechanisms for pST action are constrained by maternal competition for nutrients in rapidly growing gilts.

Genetic parameters of piglet survival and birth weight from a two-generation crossbreeding experiment under outdoor conditions designed to disentangle direct and maternal effects1

Multivariate Bayesian linear-threshold models were used to estimate genetic parameters of peri- and postnatal piglet survival and individual birth weight of piglets reared under outdoor conditions. Data of 21,835 individual piglet observations were available from a 2-generation crossbreeding experiment selected for direct and maternal genetic effects of postnatal piglet survival on piglet and dam levels, respectively. In the first generation, approximately one-half of the Landrace sires used were selected for large or average breeding values of maternal genetic effects on postnatal piglet survival, whereas in the second generation the Large White sires used were selected for direct genetic effects of the same trait. Estimates of direct and maternal heritability were 0.21 and 0.15, 0.24 and 0.14, and 0.36 and 0.28 for piglet survival at birth and during the nursing period, and individual birth weight, respectively. In particular, direct heritabilities are substantially larger than those from the literature estimated for indoor-reared piglets, suggesting that genetic effects of these traits are substantially greater under outdoor conditions. Direct or maternal genetic correlations between survival traits or with birth weight were small (ranging from 0.06 to 0.17), indicating that peri- and postnatal survival are genetically under rather different control, and survival was only slightly positively influenced by birth weight. There were significant (P < 0.05) negative genetic correlations between direct and maternal genetic effects within each of the analyzed traits ranging from -0.36 to -0.45, which have to be considered when selecting for piglet survival. Adjustment of traits for litter size or inclusion of genetic groups showed insignificant effects on the magnitude of the estimated genetic parameters. The magnitude of genetic parameters suggested that there is substantial potential for genetic improvement of survival traits and birth weight in direct and maternal genetic effects, especially when piglets are kept under outdoor conditions.