Survival analysis from birth to slaughter of Ripollesa lambs under semi-intensive management

The survivability from birth to slaughter of 1,487 Ripollesa lambs with a preslaughter overall mortality of 9.6% was studied under the proportional hazards framework, assuming a Weibull distribution for the baseline hazards function. A sire frailty model was fitted, with the common environment received by the lamb as an additional random source of variation. Common environment was considered time-dependent and was characterized by the dam and the contemporary lamb group during the preweaning and fattening periods, respectively. Only 3 fixed effects were statistically significant: the linear and quadratic effects of birth weight (P < 0.001), the relative position of the delivery within the lambing season (P < 0.001), and the presence of stillbirths or mummified fetuses within the litter (P < 0.05). Birth type and parity of the ewe were significant only when birth weight was removed from the model (P < 0.001 and P < 0.05, respectively). Nevertheless, the model including birth weight became preferable according to the Akaike's information criterion. Survivability dramatically decreased with extreme birth weights, although it reached a survival probability greater than 93.5% within the 3.3 to 5.4 kg range, indicating an optimum birth weight range of Ripollesa lambs for survival purposes. The hazard ratio (HR) increased for births occurring within the last third of the lambing period (HR = 1.70; P < 0.05), as well as for primiparous ewes that lambed in December and January (HR = 5.36; P < 0.001). Survival probability decreased for lambs born from litters with 1 or more stillbirths or mummified fetuses (HR = 1.61; P < 0.05). The variance component estimated for sire variance (0.07) was clearly lower than that of the common environment (1.87), with a heritability estimate of 0.027.     

Effects of oral doses of corn oil and other factors on preweaning survival and growth of piglets

Piglets were provided supplemental energy as oral doses of corn oil to find whether such treatment might improve survival or weight gains. A total of 1,840 piglets from 182 litters was used. Piglets were allotted to dosed and control treatments within litter on the basis of body weight. Dosed piglets received a total of 8 ml of corn oil in four doses during the first 48 h postpartum. The survival rate to weaning was high and not affected (P greater than .10) by the corn oil doses. Deaths of piglets low in birth weight were delayed by the fat doses, suggesting some utilization. The fat doses did not affect piglet weight gain. Factors affecting preweaning survival and growth of piglets were also evaluated using data from the same piglets. Specific factors investigated were sex, parity of dam, birth weight, litter size and the mean and standard deviation of piglet birth weights within litters. Male piglets were heavier at birth than females, but there was no sex effect on weight at 7 d or at weaning. Small males were less likely to survive to 3 d than were small females. Litters from primiparous sows were smaller at birth and weaning, but had lower percentages of stillbirths and of preweaning deaths than did those from multiparous sows. Piglets from primiparous sows were more uniform in birth weight. Piglets that were heavier at birth grew faster and were more likely to survive. Litter size affected growth but not survival of piglets. A heavier average birth weight in the litter reduced slightly the growth rate of individual piglets. An increase in variability of piglet birth weight within a litter was associated with an increase of the percentages of stillbirths and of preweaning mortality. A few litters accounted for a major portion of the mortality. Much of the variation in piglet mortality and growth was not explained by factors considered.     

Survival analysis of preweaning piglet survival in a dry-cured ham-producing crossbred line

The aim of this study was to investigate piglet preweaning survival and its relationship with a total merit index (TMI) used for selection of Large White terminal boars for dry-cured ham production. Data on 13,924 crossbred piglets (1,347 litters), originated by 189 Large White boars and 328 Large White-derived crossbred sows, were analyzed under a frailty proportional hazards model, assuming different baseline hazard functions and including sire and nursed litter as random effects. Estimated hazard ratios (HR) indicated that sex, cross-fostering, year-month of birth, parity of the nurse sow, size of the nursed litter, and class of TMI were significant effects for piglet preweaning survival. Female piglets had less risk of dying than males (HR = 0.81), as well as cross-fostered piglets (HR = 0.60). Survival increased when piglets were nursed by sows of third (HR = 0.85), fourth (HR = 0.76), and fifth (HR = 0.79) parity in comparison with first and second parity sows. Piglets of small (HR = 3.90) or very large litters (HR >1.60) had less chance of surviving in comparison with litters of intermediate size. Class of TMI exhibited an unfavorable relationship with survival (HR = 1.20 for the TMI top class). The modal estimates of sire variance under different baseline hazard functions were 0.06, whereas the variance for the nursed litter was close to 0.7. The estimate of the nursed litter effect variance was greater than that of the sire, which shows the importance of the common environment generated by the nurse sow. Relationships between sire rankings obtained from different survival models were high. The heritability estimate in equivalent scale was low and reached a value of 0.03. Nevertheless, the exploitable genetic variation for this trait justifies the inclusion of piglet preweaning survival in the current breeding program for selection of Large White terminal boars for dry-cured ham production.     

Production traits of litters in 2 crossbred Duroc pig lines

Genetics of different pig lines affects litter size, birth weight, and neonatal losses. Low birth weight has long been associated with neonatal losses, but piglet body mass index is reported to show stronger correlation with stillbirth. The aim of this study was to investigate differences in litter size, number of stillborn piglets, piglet BW gain, and body mass index between 2 different Duroc crossbred lines. Landrace × Yorkshire sows in 2 farms (n = 89) were divided into 2 groups on each farm. One group of sows on each farm was inseminated with semen from Landrace × Duroc boars (boar group LD, n = 48), and the other was inseminated with semen from purebred Duroc boars (boar group DD, n = 41). Piglets were monitored from birth to weaning at the age of 5 wk. Litter size in boar group LD was larger than in boar group DD (P = 0.03). Number of stillborn piglets in boar group LD tended to be greater than in boar group DD (P = 0.07). Piglets in boar group DD had a greater BW at birth (P = 0.02) and at 3 wk (P = 0.01) than those in boar group LD. Body mass index from birth to weaning was greater in piglets in boar group DD vs. LD (P < 0.01), and both BW and body mass index of liveborn piglets at birth for both groups combined showed a positive correlation with survival at weaning (P < 0.01). In conclusion, breeding for larger litter size in boar group DD may be one approach to increase the number of vigorous piglets in production, but the inverse relationship between litter size and birth weight was more pronounced for this group than for boar group LD (P = 0.03). Further studies of the impact of litter size on BW gain are necessary before a final conclusion can be reached.     

Causes of preweaning mortality on a large intensive piggery

Causes of preweaning mortality were examined on a large intensive piggery. Diagnosis was made using comprehensive clinical histories combined with post-mortem data. Two thousand four hundred and twenty-six piglets were born in 238 litters. Pre-parturient and parturient losses were 2.9% and 5.4% of the total numbers of piglets born. Birth to weaning mortality was 11.3%. Among piglets born alive, overlaying was the most frequent cause of death (2.1%), followed by deaths due to diarrhoea (1.7%), anaemia (1.2%), savaging (1.1%) and losses of small weak piglets (0.9%). Most deaths, including stillbirths, were associated with below average birth weight, and two-thirds of all deaths of liveborn pigs occurred within 4 days of birth. Increased litter size resulted in decreased birth weights, an increased percentage of stillborn piglets and mummified foetuses, but duration of parturition was not affected. Stillborn piglets were born late in the litter and after a longer interval between pigs born (interpig interval). Over 70% of deaths due to overlay were in previously healthy piglets, but some were associated with illness of the sow (18%) or both sow and piglet (3%). Savaging was confined mainly to first parity sows and was responsible for 20% of all deaths in these litters. Sixty-two per cent of all piglets with a birth weight of less than 800g were stillborn or died before weaning compared with 18.7% mortality for all piglets. Anaemia in piglets was considered to be due to umbilical haemorrhage. Anaemic piglets had a 36% mortality to weaning compared with 10% for non-anaemic piglets.(ABSTRACT TRUNCATED AT 250 WORDS)     

Between-breed variability of stillbirth and its relationship with sow and piglet characteristics

Litter characteristics at birth were recorded in 4 genetic types of sows with differing maternal abilities. Eighty-two litters from F(1) Duroc x Large White sows, 651 litters from Large White sows, 63 litters from Meishan sows, and 173 litters from Laconie sows were considered. Statistical models included random effects of sow, litter, or both; fixed effects of sow genetic type, parity, birth assistance, and piglet sex, as well as gestation length, farrowing duration, piglet birth weight, and litter size as linear covariates. The quadratic components of the last 2 factors were also considered. For statistical analyses, GLM were first considered, assuming a binomial distribution of stillbirth. Hierarchical models were also fitted to the data to take into account correlations among piglets from the same litter. Model selection was performed based on deviance and deviance information criterion. Finally, standard and robust generalized estimating equations (GEE) procedures were applied to quantify the importance of each effect on a piglet's probability of stillbirth. The 5 most important factors involved were, in decreasing order (contribution of each effect to variance reduction): difference between piglet birth weight and the litter mean (2.36%), individual birth weight (2.25%), piglet sex (1.01%), farrowing duration (0.99%), and sow genetic type (0.94%). Probability of stillbirth was greater for lighter piglets, for male piglets, and for piglets from small or very large litters. Probability of stillbirth increased with sow parity number and with farrowing duration. Piglets born from Meishan sows had a lower risk of stillbirth (P < 0.0001) and were little affected by the sources of variation mentioned above compared with the 3 other sow genetic types. Standard and robust GEE approaches gave similar results despite some disequilibrium in the data set structure highlighted with the robust GEE approach.     

Variables related to the progress of parturition and probability of stillbirth in swine

Sow and piglet variables related to probability of stillbirth and to viability score were analyzed in litters from 98 multiparous Yorkshire sows. Immediately after the birth of each piglet, viability was scored using Randall's method. Sow variables related to the probability of stillbirth were average birth weight of the litter (p = 0.0001), sow age (p = 0.001), sow condition score (p = 0.003), length of gestation (p = 0.005), and number of piglets in the litter (p = 0.01). Sow variables related to average viability score were average birth weight of the litter (p = 0.001), standard deviation in birth weight in the litter (p = 0.02), sow age (p = 0.03), sow condition score (p = 0.03), and length of gestation (p = 0.03). Piglet variables related to probability of stillbirth were piglet hemoglobin (p = 0.0001), position in the birth order (p = 0.0001), broken umbilical cord (p = 0.0004), and preceding birth interval (p = 0.0004). Piglet variables related to viability score were piglet hemoglobin (p = 0.0001), position in the birth order (p = 0.0001), broken umbilical cord (p = 0.0001), preceding birth interval (p = 0.0001), and birth weight (p = 0.004). Preceding birth interval was related to whether the piglet was live or stillborn (p = 0.0001), to position in the birth order (p = 0.003), and to the sex of the piglet (p = 0.03).

The results demonstrated that sow and piglet variables were highly correlated to probability of stillbirth and to viability score. In addition it was also found that the probability of stillbirth was not associated with the duration of farrowing but with the number of piglets in the litter and piglet hemoglobin level. This study also found that lower weight piglets tend to have poor viability, but are not more prone to stillbirth as commonly suggested. These low viability piglets may survive if the necessary care is given during the farrowing process.

     

Contributions of the maternal uterine environment and piglet genotype on weaning survivability potential: I. Development of neonatal piglets after reciprocal embryo transfers between Meishan and White crossbred gilts

In commercial pigs, the greatest susceptibility for pre-weaning mortality occurs in low birth-weight piglets. Despite their overall decreased birth weight, Meishan (MS) piglets have decreased pre-weaning mortality rates compared with contemporary Western breeds. The objective of the current study was to determine the contributions of the maternal uterine environment, piglet genotype, and their interaction on the development of neonatal piglets pertaining to pre-weaning survivability using reciprocal embryo transfer between MS and White crossbred (WC) pigs. Twenty-five successful pregnancies were produced from 2 farrowing seasons, generating litters of maternal uterine environment (MUE) by piglet genotype (PigG) combinations; MS × MS (n = 4 litters), MS × WC (n = 7 litters), WC × MS (n = 7 litters), and WC × WC (n = 7 litters). At approximately 24 h of age (Day 1), piglets (n = 173) were weighed and a blood sample was taken. Hematocrit, hemoglobin, glucose, plasma urea nitrogen, albumin, NEFA, lactate, and cortisol were measured in all blood samples. Representative piglets (n = 46) from each litter were harvested and body measurements (i.e., organ weights, tissue glycogen content, and body composition) were determined. Piglet data were analyzed by ANOVA using MIXED model procedures. Both MUE (P < 0.001) and PigG (P < 0.01) affected piglet BW, illustrating that piglets gestated in WC gilts were heavier than piglets gestated in MS gilts, and WC piglets were heavier than MS piglets. Serum albumin concentrations were increased (P < 0.05) in MS piglets compared with WC piglets, indicating greater liver maturity. Significant MUE × PigG interactions were observed for hematocrit and hemoglobin, in which the greatest concentrations were observed in MS piglets gestated in MS and WC gilts, and the lowest concentrations were observed in WC piglets gestated in WC gilts, demonstrating increased oxygen-carrying capability. The percentage of fat and nitrogen, as well as the GE of the body, were greater (P < 0.05) in MS piglets, indicating greater energy stores. Liver, bicep femoris, and LM glycogen concentrations were greater (P < 0.01) in WC piglets compared with MS piglets, demonstrating increased glycogen catabolism in MS piglets. This study demonstrated limited interactions between the maternal uterine environment and piglet genotype on weaning survivability potential, suggesting that the MS piglet is a viable model for pre-weaning survivability.     

猪窝产活仔数与初生窝重、21日龄窝重的相关分析

测定84头新关系杜洛克母猪的窝产活仔数、分娩胎次、初生窝重、21日龄窝重,分别按照窝产活仔数分组进行方差分析和性状间的相关回归分析,探讨分娩胎次对猪繁殖性状的影响。结果表明：窝产活仔数、初生窝重、21日龄窝重组间差异均呈极显著（P〈0．01）,初生窝重在窝产活仔猪数为9头和10头,7、8、9头差异不显著,其余各组之间差异显著或极显著。21日龄窝重在窝产活仔数为7、8、9、10、13头之间差异均不显著。对窝产活仔数与分娩胎次、初生窝重、21日龄窝重进行相关分析,分娩胎次与21日龄窝重指标不相关,其余各组指标均达到极显著（P〈0．01）水平。综合分析表明猪窝产活仔数在10～12头可取得最佳经济效益．     

Genetic parameter estimates among scale activity score and farrowing disposition with reproductive traits in swine

The primary objective of this study was to determine if certain behavior traits were genetically correlated with reproduction. If 1 or both of the behavior traits were found to be correlated, a secondary objective was to determine if the behavior traits could be useful in selecting for more productive females. A scale activity score taken at 5 mo of age and a farrowing disposition score taken at farrowing were selected as the behavioral traits. Scale activity score ranged from 1 to 5 and farrowing disposition ranged from 1 to 3. Reproductive traits included age at puberty, number born alive, number born dead, litter birth weight, average piglet birth weight, number weaned, litter weaning weight, average weaning weight, wean-to-estrus interval, ovulation rate including gilts, and postweaning ovulation rate. Genetic correlations between scale activity score and reproduction ranged from -0.79 to 0.61. Three of the correlations, number born alive (P < 0.01), average piglet birth weight (P < 0.001), and wean-to-estrus interval (P = 0.014), were statistically significant but included both favorable and antagonistic correlations. In contrast, all but 1 of the farrowing disposition correlations was favorable and ranged from -0.66 to 0.67. Although only the correlation with litter birth weight was significant (P = 0.018), the consistent favorable direction of all farrowing disposition correlations, except average weaning weight, shows a potential for inclusion of farrowing disposition into a selection program.     

Effects of sarcoptic mange on lactating swine and growing pigs

The impact of Sarcoptic mange on sows and on performance of their offspring from birth to slaughter was determined. Sows naturally infested with Sarcoptic mange were paired, mated to the same boar, and assigned randomly to treated or control farrowing groups. Treated sows received ivermectin s.c. at 300 micrograms/kg body weight; control sows received the vehicle s.c. Sow performance was evaluated via sow feed consumption, litter size, litter birth weights, litter weaning weights and piglet death loss from birth to weaning. Seven replicates (farrowing groups), each with six sow pairs, were included in the trial. Offspring from treated and control sows, 35 head/group, were fed to slaughter weights. Untreated sows had litters that weighed 4.14 kg less than ivermectin-treated sow litters at 21 d (P less than .07). Treated sows consumed 1.95 kg less feed per weaned piglet and .13 kg less feed per kilogram of weaned piglet (P less than .05). Piglets from treated sows were 5.79 kg/head heavier at slaughter (P less than .05) and had a .05 kg/d superior average daily gain (P less than .05).     

Breed and heterotic effects on postweaning traits in Altex and New Zealand White straightbred and crossbred rabbits

Postweaning data from 1,111 straightbred and reciprocally crossbred rabbits were analyzed to evaluate Altex and New Zealand White (NZW) breeds for individual growth and litter traits. The Altex is a recently developed sire breed, whereas the NZW is a popular commercial dam breed. Individual fryer growth traits were weaning (28 d; WW) and market (70 d; MW) weights and ADG. Litter traits included litter size (LSW) and total weight of litter at weaning (LWW), 28 to 70 d total feed intake (LFI), feed efficiency (LFE = total litter gain/LFI), survival rate, and within-litter MW uniformity. Least squares models consisted of fixed effects of sire breed, dam breed, season of weaning, doe parity, two- and three-way interactions, and random effects of sire within sire breed, litter within sire x dam breed, and(or) residual error (depending on whether an individual or a litter trait was analyzed). Crossbreeding parameters (direct breed additive, maternal breed, and individual heterosis) were estimated. Altex sires increased WW, ADG, and MW by 40 g (P < 0.10), 2.5 g/d, and 152 g (P < 0.001), respectively. Individual growth traits were not significantly influenced by the maternal breed effect. Litter size at weaning and LWW means were numerically similar for Altex and NZW dams. Direct heterosis increased ADG (1.7 g/d; P < 0.01) and MW (66 g; P < 0.10). In straightbred Altex compared to NZW fryers, ADG and MW were increased by 3.6 g/d and 216 g, respectively (P < 0.001). In Altex (sire) x NZW (dam) crossbred compared to NZW straightbred fryers, WW and MW were heavier (55 and 218 g; P < 0.10 and < 0.001) and ADG was more rapid (4.2 g/d; P < 0.001). For litter traits, Altex compared to NZW sires increased LFI by 1.28 kg (P < 0.10). Individual crossbreeding parameters did not affect (P > 0.05) other litter traits. No relationship existed between breed type of fryer and survival status (chi2 = 2.81; P > 0.25). For litter traits, straightbred Altex had significantly greater LFI by 2.45 kg and increased LFE by 0.015 units relative to NZW. Combined direct breed additive and heterosis effects increased LFI by 1.84 kg (P < 0.05) in Altex (sire) x NZW (dam) crossbreds compared to NZW straightbreds. Also, 25% more Altex (sire) x NZW (dam) crossbred fryers were marketable (body weight > or = 1.8 kg) by 63 d of age than NZW straightbred fryers. These data suggest that crossing Altex bucks to NZW enhanced breeding efficiency of fryer growth performance.     

Milk production of crossbred daughters of high- and low-milk EPD Angus and Hereford bulls.

Milk yield from 273 Angus- and Hereford-sired cows and preweaning performance of their calves were used to determine how accurately milk EPD of Angus and Hereford sires predicted milk production of crossbred daughters and subsequent calf performance. Mean milk EPD (kg) for high Angus (HA), low Angus (LA), high Hereford (HH), and low Hereford (LH) bulls (n = 41) selected as sires were +8.7, -6.2, +7.6, and -4.8, respectively. Cows calved in spring or fall from 1992 to 1997 and yielded a total of 660 records. Twenty-four-hour milk production of the cows was estimated by two weigh-suckle-weigh measurements at monthly intervals. The statistical model included breed, milk EPD level, sire of cow within breed and milk EPD level, year, season, cow age, calf sire, sex, and all two- and three-way interactions. Means were obtained for monthly milk production, total milk production, time and yield of peak production, monthly calf weights, monthly cow weights and body condition scores (1 through 9), and calf birth and weaning data. The least squares means for 24-h milk production (kg) of HA, LA, HH, and LH with P-values for high vs low, across breeds, were, respectively, as follows: mo 1: 6.9, 5.9, 7.1, and 5.7 (P < 0.01); mo 2: 7.2, 6.1, 6.9, and 5.7 (P < 0.01); mo 3: 6.1, 5.1, 5.1, and 4.3 (P = 0.01); mo 4: 6.1, 4.9, 4.9, and 4.8 (P = 0.01); mo 5: 4.8, 4.0, 4.2, and 3.8 (P = 0.01); mo 6: 4.7, 3.4, 3.2, and 3.0 (P < 0.01); and mo 7: 3.7, 2.5, 3.0, and 3.0 (P = 0.05). Least squares means for total milk (kg) were 911.4, 729.6, 758.0, and 664.2 (P < 0.01); for yield at peak (kg/d) were 7.0, 5.7, 6.1, and 5.2 (P < 0.01); for birth weight (kg) were 37.1, 37.9, 38.3, and 38.8 (P = 0.31); for 205-d weight (kg) were 237.3, 218.2, 222.2, and 214.1 (P < 0.01); for final cow weight (kg) were 482.4, 505.4, 509.5, and 511.7 (P = 0.11); and for final cow BCS were 4.9, 5.3, 5.1, and 5.2 (P < 0.01). The correlations of total production with the monthly productions were 0.52, 0.56, 0.52, 0.54, 0.35, 0.37, and 0.31 (P < 0.01) and were 0.12 with birth weight, 0.45 with 205-d weight, -0.12 with final cow weight, and -0.26 with final cow body condition score (all P < 0.01). Daughters of high-milk EPD sires produced more milk and weaned heavier calves than those of low-milk EPD sires at the expense of body condition. These results suggest that sire milk EPD are sufficiently associated with milk yield and calf performance to be useful tools in genetic improvement of preweaning performance.     

Space allowance for dry, pregnant sows in pens: body condition, skin lesions, and performance

Different floor space allowances for dry, pregnant sows in pens were evaluated to determine the impacts of space on sow performance, productivity, and body lesions during 2 consecutive farrowings. Treatment groups of 5 sows/pen were assigned to 1.4, 2.3, or 3.3 m(2) of floor space/sow or of 5 sows in individual stalls (1.34 m(2)). The experiment consisted of 6 replications (blocks 1 to 6), and within each block measurements were recorded for 2 consecutive pregnancies and farrowings. A total of 152 sows were measured at 1 farrowing, and 65 of those sows were measured at the successive farrowing (n = 217 records). Performance traits were BCS, BW, backfat (BF), days until rebred, and proportion culled. Litter traits were number of piglets born alive, male:female ratio, and proportions of stillborn, mummified, or dead piglets after birth. Litter performance measures were mean piglet BW and gain and litter BW. Lesion scores were assessed for several body regions. There were treatment and parity effects and interactions for several traits. An interaction of space treatment and parity occurred for sow mean BW, d-110 BW, BF, litter size, and litter and piglet BW and gain, with most effects in parity 2, 3, and 4 sows. Space affected sow mean (P < 0.001) and d-110 BW (P < 0.05) and mean BF and adjusted BF (P < 0.001); sows in pens at 相似文献   

Prenatal and preweaning deaths caused by pseudorabies virus and porcine parvovirus in a swine herd

Sequential outbreaks of pseudorabies virus and porcine parvovirus infections were documented at a swine farm in southern Minnesota. Data for the prevalence of mummified fetuses born and the preweaning mortality were recorded over a 3-year-period. The farm was a farrow-to-finish facility, with breeding females housed in 4 groups according to their stage of pregnancy. The herd consisted of approximately 130 breeding females in December 1981, and expanded to 220 females during the 12 months of 1982. Excluding the outbreaks, the mean preweaning mortality was 20.43% (SE 1.59) and the number of mummified fetuses per litter was 0.19 (SE 0.01). An outbreak of porcine parvovirus infection caused the preweaning mortality and number of mummified fetuses to increase to 50% and 4.10 per litter, respectively. Two outbreaks of pseudorabies 27 months apart, caused the preweaning mortality to increase to 95% and 82%, and the number of mummified fetuses to increase to 0.96 and 1.25 mummified fetuses per litter, respectively. The increase in mummification was observed 1 month after the increase in preweaning mortality caused by pseudorabies virus infections, whereas the increase in mummification and preweaning mortality was simultaneous with porcine parvovirus infections.     

Polwarth and Texel ewe parturition duration and its association with lamb birth asphyxia

The objective of the present study was to test the hypothesis that parturition duration is related to birth asphyxia in lambs and that asphyxia affects newborn lamb viability and vigor. Two sire and dam genotypes (Texel: TX; Polwarth: PW) and their crosses were represented in the study. Eighty lambs (25 PW sire × PW dam, 13 TX × TX, 25 TX × PW, and 17 PW × TX) born to 69 grazing ewes were used. At birth, the log?? length of the second stage of parturition, birth weight, placental weight, and several body measurements were recorded on all lambs, and jugular blood samples were analyzed with the i-Stat Portable Clinical Analyzer (Abbott, Montevideo, Uruguay). A modified Apgar viability score at birth and lamb behavior during their first hour of life were recorded. Brain weight, muscle:bone ratio, and bone density were recorded in 20 male lambs (5 from each breed group) that were euthanized and dissected 24 h after birth. Data were analyzed by linear regression, least squares ANOVA, and ordinal and binary logistic regressions. Mean blood gas and acid-base variables were 7.21 ± 0.09 for pH, 18.4 ± 9.8 mmHg for partial pressure of oxygen, 53 ± 12.5 mmHg for partial pressure of carbon dioxide, and -4 ± 5.1 mmol/L for extracellular fluid base excess. Parturition duration increased with birth weight (P < 0.001) and was shorter in TX ewes (P < 0.001), female lambs (P < 0.05), twins (P < 0.09), and twin females (sex × litter size interaction, P < 0.02). Twenty-six (32.9%) lambs were born asphyxiated (pO? < 10 mmHg or pH <7.1). Parturition duration increased the risk of asphyxia (P < 0.001), decreased the viability score (P < 0.001), and increased the latency to suckle the udder (P < 0.05). Twin-born lambs presented at birth a 16-fold greater risk of asphyxia (P < 0.01) and reduced placental efficiency (P < 0.05). Texel-sired lambs appeared immature at birth, with less bone density (P < 0.05), smaller brain (P < 0.05), shorter forelimbs (P < 0.05), greater anterior (P < 0.001) and posterior (P < 0.05) neck circumference, and greater muscle:bone ratio (P < 0.05). Immaturity may explain greater TX biotype survival. Together these results demonstrate that a relationship exists between parturition duration, neonatal viability and behavior, and acid-base balance values in single- and twin-born lambs, suggesting that birth asphyxia is an important risk factor in perinatal lamb mortality.     

Within-litter variation of birth weight in hyperprolific Czech Large White sows and its relation to litter size traits, stillborn piglets and losses until weaning

Data from about 2900 litters (approximately 40,000 piglets) originating from 1063 Czech Large White hyperprolific sows were analyzed. The phenotypic and genetic relations between litter size traits, piglet mortality during farrowing and from birth to weaning and several statistics referring to the distribution of the birth weight within litter were analyzed. All genetic parameters were estimated from multi-trait animal models including the following factors: mating type (natural service or insemination), parity, linear and quadratic regression on age at first farrowing (1st litter) or farrowing interval (2nd and subsequent litters), herd-year-season effect and additive-genetic effect of the sow. The phenotypic correlations of the mean birth weight with the total number of piglets born and piglets born alive were − 0.30. Traits describing the variability of the birth weight within litter (range, variance, standard deviation, coefficient of variation) were mostly positively correlated with litter size. A statistically significant phenotypic correlation (− 0.09 to − 0.15) between mean birth weight and losses at birth and from birth to weaning was found. The heritability for the number of piglets born, piglets born alive and piglets weaned was around 0.15. The number of stillborn piglets had only a very low heritability less than 0.05, whereas the heritability for losses from birth to weaning was 0.13. The heritabilities of the mean, minimal and maximal birth weight were 0.16, 0.10 and 0.10, respectively. The heritability for all statistics and measures referring to the variability of the birth weight within litter was very low and did never exceed the value of 0.05. An increase in litter size was shown to be genetically connected with a decrease in the mean piglet birth weight and an increase in the within-litter variability of birth weight. Selection on litter size should be accompanied by selection on mortality traits and/or birth-weight traits. Losses from birth to weaning and the minimal birth weight in the litter were proposed as potential traits for a selection against piglet mortality.     

Correlated response in placental efficiency in swine selected for an index of components of lifter size

The objective of this study was to evaluate correlated response in placental efficiency to selection for components of litter size. Fourteen generations of selection had resulted in a difference between lines of three fully formed piglets at birth. Gilts from a line selected for an index of components of litter size (S, n = 33) and a randomly selected control (C, n = 27) were observed at farrowing. At delivery, the umbilical cord of each piglet was double tagged with identically numbered mouse ear tags to allow the piglet's weight to be matched to the corresponding placental weight. Litter size, placental weight, birth weight, and placental vascularity were recorded. Litter size was higher (12.0 +/- 0.7 vs 7.9 +/- 0.7) in S than in C (P < 0.001). Line differences in placental vascularity were not significant with or without adjustment for litter size (P = 0.45 and 0.39, respectively). Correlated response to selection for components of litter size resulted in a reduced birth weight (S 82.6% of C, P < 0.001) and a reduced placental weight (S 90.9% of C, P = 0.11). After adjusting for litter size, line differences in neither placental weight nor birth weight were significant (P = 0.40 and 0.07, respectively), which indicates that the reduction in birth weight was, for the most part, due to the increase in litter size. The result of the difference in the magnitude of the change for both weights was that placental efficiency, measured as the ratio of birth weight:placental weight was 0.43 higher in C (P = 0.05). Adjustment for litter size increased the difference in placental efficiency to 0.52 (P = 0.02). Since a significant difference in litter size favoring the selected line was observed, we hypothesize that this physiological response was achieved through mechanisms other than improved placental efficiency.     

Using haplotype probabilities in categorical survival analysis: a case study with three candidate genes in an Iberian x Meishan F2 population of newborn piglets.

Haplotype probabilities have been implemented in association analyses performed between three candidate genes and the preweaning survival of F2 Iberian x Meishan piglets, under a categorical proportional hazard model. The additive effect of substitution of each haplotype was estimated using information of parental genotypes for non-genotyped piglets. Analysed loci were the bone morphogenetic protein type 1B receptor (BMPR1B) gene at 8q25 (three SNPs; haplotypes BMPR1B A, BMPR1B B, BMPR1B C and BMPR1B D), the dopamine beta-hydroxylase (DBH) gene at 1q2.13 (two SNPs; haplotypes DBH X, DBH Y and DBH Z), and the prolactin receptor (PRLR) gene at 16q1.4-q2.3 (six SNPs; haplotypes PRLR A, PRLR B, PRLR C, PRLR D and PRLR E). The number of analysed records were 899 (BMPR1B), 850 (DBH) and 822 (PRLR) with a censoring percentage ranged between 87 and 89%. Associations with preweaning survival were suggested for BMPR1B (p < 0.10) and associations were clearly significant for DBH haplotypes (p < 0.05), whereas the PRLR locus did not reach statistical significance (p > 0.10). The BMPR1B A haplotype could increase piglet survivability in relation to the BMPR1B B haplotype with a hazard ratio of 0.751 and a confidence interval (CI) between 0.550 and 1.025 (p < 0.10). The two remaining haplotypes did not differ significantly from the BMPR1B B haplotype, with a hazard ratio higher than 0.90 (p > 0.10). For the DBH locus, the DBH X and the DBH Z haplotypes were associated with an improved preweaning survival in relation to the DBH Y haplotype. The advantage for DBH X in terms of hazard ratio was 0.789 (CI = 0.625 to 0.994; p < 0.05) and differences between DBH Y and DBH Z reached a hazard ratio of 0.770 (CI = 0.606 to 0.977; p < 0.05). Although further researches are required, BMPR1B and DBH genes could be a useful tool to improve piglet survival under a marker assisted selection strategy.     

Birth to weaning kid traits from a complete diallel of Boer, Kiko, and Spanish meat goat breeds semi-intensively managed on humid subtropical pasture

Boer, Kiko, and Spanish meat goats were semi-intensively managed in a complete 3-breed diallel mating scheme to evaluate genetic effects on preweaning kid performance. Over a 6-yr period, 1,547 kids were born in March and May with 1,173 kids raised by their dams to weaning at 3 mo of age. March-born kids were lighter (P < 0.01) at birth, but had greater (P < 0.01) preweaning ADG and survival rates and heavier (P < 0.01) weaning weights than May-born kids. For birth weight, the direct Boer effect was positive (P < 0.01) and direct effects were negative (P < 0.01) for Kiko and Spanish. The direct Kiko effect for preweaning ADG was positive (P < 0.05), whereas other direct breed effects for ADG and all direct effects for weaning weight did not differ from 0 (P > 0.10). Maternal Boer effects were negative (P < 0.01) for birth weight and weaning weight, whereas maternal Kiko effects were significantly (P < 0.05) positive for preweaning ADG and weaning weight. Maternal Spanish effect was positive (P < 0.05) for birth weight, but did not differ from 0 (P > 0.5) for preweaning ADG or weaning weight. Heterosis for birth weight was exhibited (P < 0.01) for each pair of breed crosses, but only between Boer and Kiko for ADG and weaning weight. Kiko and Spanish dams had greater (P < 0.01) preweaning kid survival rates than Boer dams, but the former 2 did not differ (P = 0.72). Significant genetic variation was observed between meat goat breeds for kid performance to weaning. Maternal breed effects were more influential than direct breed effects. Boer goats were not superior to Kiko or Spanish for preweaning kid performance when semi-intensively managed on humid, subtropical pasture. Kiko should be a preferred breed and to a lesser extent Spanish for enhancing birth to weaning kid performance. Findings of this study emphasize the importance of proper doe breed selection in achieving desired kid performance to weaning in meat goats.