Shorter Gestation Length Research Articles

Birth and weaning traits in crossbred cattle from Hereford, Angus, Brahman, Boran, Tuli, and Belgian Blue sires12

The objective of this study was to characterize breeds representing diverse biological types for birth and weaning traits in crossbred cattle. Gestation length, calving difficulty, percentage of unassisted calving, percentage of perinatal survival, percentage of survival from birth to weaning, birth weight, BW at 200 d, and ADG were measured in 2,500 calves born and 2,395 calves weaned. Calves were obtained by mating Hereford, Angus, and MARC III (one-fourth Hereford, one-fourth Angus, one-fourth Pinzgauer, and one-fourth Red Poll) mature cows to Hereford or Angus (British breed), Brahman, Tuli, Boran, and Belgian Blue sires. Calves were born during the spring seasons of 1992, 1993, and 1994. Sire breed was significant for all traits (P < 0.002). Offspring from British breeds and the Belgian Blue breed had the shortest gestation length (285 d) when compared with progeny from other sire breeds (average of 291 d). Calving difficulty was greater in offspring from Brahman sires (1.24), whereas the offspring of Tuli sires had the least amount of calving difficulty (1.00). Offspring from all sire breeds had similar perinatal survival and survival from birth to weaning (average of 97.2 and 96.2%, respectively), with the exception of offspring from Brahman sires, which had less (92.8 and 90.4%, respectively). Progeny of Brahman sires were heaviest at birth (45.7 kg), followed by offspring from British breed, Boran, and Belgian Blue sires (average of 42.4 kg). The lightest offspring at birth were from Tuli sires (38.6 kg). Progeny derived from Brahman sires were the heaviest at 200 d (246 kg), and they grew faster (1.00 kg/d) than offspring from any other group. The progeny of British breeds and the Belgian Blue breed had an intermediate BW at 200 d (238 kg) and an intermediate ADG (average of 0.98 kg/d). The progeny of Boran and Tuli sires were the lightest at 200 d (227 kg) and had the least ADG (0.93 kg/d). Male calves had a longer gestation length, had a greater incidence of calving difficulty, had greater mortality to weaning, were heavier, and grew faster than female calves. Sire breed effects can be optimized by selection and use of appropriate crossbreeding systems.

Maternal Psychosocial Adversity During Pregnancy Is Associated With Length of Gestation and Offspring Size at Birth: Evidence From a Population-Based Cohort Study

To study in a large-scale cohort with prospective data the associations of psychosocial adversities during pregnancy with length of gestation and offspring size at birth. We defined a priori two types of psychosocial adversity during pregnancy: life stress (perceived burdens in major areas of life) and emotional symptoms (e.g. anxiety). Measures of offspring size at birth, including body weight, body length, abdominal and head circumference, were obtained from a national medical birth registry. We included in the analyses gestational age and offspring size at birth controlled for length of gestation; the latter was calculated by gestational-age-specific z scores (ZS) reported in 10(-3). We conducted multiple regression analyses adjusted for potential confounders to estimate the association between exposures and birth outcomes (n = 78017 pregnancies). Life stress (per score increase by 1; range, 0-18) was associated with shorter length of gestation (days; B, -0.14; 95% confidence interval (CI), -0.19, -0.10), increased offspring body weight (ZS; B, 9.14; 95% CI, 4.99, 13.28), body length (ZS; B, 6.58; 95% CI, 2.39, 10.77), abdominal circumference (ZS; B, 9.96; 95% CI, 5.77, 14.16), and head circumference (ZS; B, 6.13; 95% CI, 1.95, 10.30). Emotional symptoms were associated with shorter length of gestation (days; B, -0.04; 95% CI, -0.07, -0.004) and decreased body length (ZS; B, -4.44; 95% CI, -7.57, -1.32) only. Life stress and emotional symptoms both predicted a shorter length of gestation, while only life stress predicted an increased offspring size at birth controlled for length of gestation; yet, the associations were rather small. The fetoplacental-maternal unit may regulate fetal growth according to the type of psychosocial adversity and even increase fetal growth in response to maternal stress in major areas of life. This potentially reflects a basic principle of intrauterine human development in response to stress.

Dystocia, stillbirth, gestation length, and birth weight in Holstein, Jersey, and reciprocal crosses from a planned experiment

Holstein and Jersey cows were mated to 4 Holstein (H) bulls and 4 Jersey (J) bulls to create HH, HJ, JH, and JJ genetic groups (sire breed listed first) in a diallele crossbreeding scheme. Calvings (n=756) occurred in research herds in Virginia, Kentucky, and North Carolina with 243, 166, 194, and 153 calvings in the HH, HJ, JH, and JJ groups, respectively. Birth weights (BW), dystocia scores (0 for unassisted and 1 for assisted), and stillbirth (0 for alive or 1 for dead within 48h) were recorded at calving. Gestation lengths (GL) were determined from breeding dates. An animal model was used to analyze BW and GL, and an animal model with logistic regression was used for dystocia and stillbirth. Fixed effects considered for model inclusion were genetic group, herd-year-season, sex, parity (primiparous or multiparous), twin status, and gestation length. Genetic group and effects significant in the model building process were kept in the final model for each trait. Heifer calves had lower BW, shorter GL, and had a lower odds ratio (0.53) for dystocia than bull calves. Twins had lower BW, shorter GL, were 3.86 times more likely to experience dystocia, and 7.80 times more likely to be stillborn than single births. Primiparous cows had calves with lower BW, shorter GL, were 2.50 times more likely to require assistance at birth, and were 2.35 times more likely to produce stillborns than calves from multiparous cows. Genetic group did not affect GL. Least squares means (kg) for BW were 37.7±1.1, 29.1±1.1, 30.3±1.0, and 22.5±1.3 for HH, HJ, JH, and JJ, respectively. Animals in HH weighed more than animals of other genetic groups; the JJ group had the smallest BW, with no differences for BW between HJ and JH. Probability of dystocia in JJ and JH were 5.73% and 18.98% of HH. Calves in HJ and HH were not different for dystocia. Calves in HJ were 3.38 times more likely to be stillborn than calves in JH, but no other genetic group differences were significant for probability of stillbirth. Groups HJ and JH differed for calving traits, with JH crosses experiencing less dystocia than HJ; JJ showed no indication of dystocia. No differences were observed between HH and JJ for stillbirths. Additional investigation of stillbirths in Jerseys is justified.

Evaluation of management variables to advance conception and calving date of red deer ( Cervus elaphus) in New Zealand venison production systems

The ability to shift the supply of New Zealand chilled venison from farmed yearling red deer stags to obtain premium prices in seasonal European markets necessitates early calving of hinds combined with high growth rates of their calves. Two studies over a three-year period evaluated three management variables that offer potential to advance calving date. Under the conditions of the studies there was no consistent evidence that the management practices of early stag introduction, early weaning and enhanced hind nutrition prior to conception (lactation) and pre-calving (third trimester of pregnancy) advanced conception date and calving date in red deer hinds. However, the nutrition effect was diminished by the difficultly in achieving the dietary contrast necessary for the targeted 5 kg differentiation in hind live weight at strategic times of the year. Across all hinds there was a significant pre-mating (mid-March) live weight effect on conception day in the one year in which a 5 kg difference between nutritional regimens was achieved, but the driver was live weight and not nutrition. There were significant effects of nutrition on calf growth, with the growth rates of calves weaned in mid-March significantly higher when their dams grazed a high plane of nutrition pre-conception. There were significant and consistent inverse relationships between conception day and calving date that implied variation around gestation length, with early- and late-conceiving hinds exhibiting longer and shorter gestation lengths, respectively. Across all treatments, calving date was predicted to advance by approximately 5 days for every 10-day advance in conception date. However, there was a significant carry-over effect of nutrition pre-conception on calving date, with hinds on a high plane of nutrition pre-conception exhibiting shorter (2–4 days) gestation lengths. There were also indications that hinds may manipulate gestation length in response to live weight gain pre-calving. These findings suggest that fetal growth trajectory may be the principle driver of gestation length and calving date. Although there were no direct effects of hind nutrition pre-mating on conception dates, nutrition remains an important component of the management of hinds and their calves in venison production systems. The outcomes of the 3-year program suggest that there are limited opportunities to manipulate calving date through manipulation of management variables.

Assisted fertilization and breech delivery: risks and obstetric management

Previous studies have suggested that assisted reproduction technology (ART) is associated with increased risk of breech presentation. We investigated whether factors that tend to differ between ART and spontaneously conceived pregnancies may explain the higher risk of breech deliveries associated with ART. In this population-based cohort study, we included 1 209 151 singleton pregnancies reported to the Medical Birth Registry of Norway between 1984 and 2006 and compared the risk of breech presentation in 8229 ART pregnancies with that in spontaneously conceived pregnancies. Risk ratios (RR), adjusted for maternal age, parity, gestational length and year of birth, were estimated using binominal regression, and we describe differences and time trends in obstetric management for breech and cephalic presentations after ART compared with management of spontaneously conceived pregnancies. Breech presentation occurred nearly 50% more often in ART singleton pregnancies than in spontaneously conceived singletons [crude RR: 1.48, 95% confidence interval (CI): 1.34-1.64], but after adjustment for potentially confounding factors, the difference was fully attenuated (RR: 0.97, 95% CI: 0.88-1.07). The most important contributors to the attenuation were parity and length of gestation. In general, Caesarean sections and induced deliveries were more likely in ART pregnancies, but over the study period, the proportion of Caesarean sections in ART pregnancies gradually approached that of spontaneously conceived pregnancies. Increased risk of breech presentation in pregnancies after ART is mediated by lower parity and shorter gestational length. In general, the obstetric management of women with ART pregnancies is gradually approaching the ordinary surveillance of pregnant women.

Sex‐specific Prenatal Programming

Women are four to eight times more likely to be affected by fibromyalgia syndrome (FMS). A lack of cortisol, potentially due to an adrenocortical deficit is postulated in FMS. The cause of such adrenal insufficiency is unknown. It could be assumed that stress exposure during critical periods contributes to vulnerability for FMS. These critical periods might include prenatal periods in which adversities may lead to an impaired development of the adrenal cortex, especially in females. More than 50% of FMS patients report major life events before the onset of the disease. Possibly due to adrenal insufficiency they may not be able to dampen their stress response by secreting sufficient glucocorticoids. Thus, stress mediators, such as catecholamines and pro-inflammatory cytokines, may be disinhibited and affect brain function. This might result in an enhanced responsiveness to external and internal pain- and fatigue-eliciting stimuli. In a study with female FMS patients (N= 93) those patients with a shorter gestational length (<38 weeks) showed a lower cortisol awakening response (CAR) than FMS subjects with a gestational length >38 weeks (F((3,31))= 2.94, P= 0.038). Additionally, more than 70% reported severe psychological stress alone or in combination with other factors at disease onset.

Short-term maternal psychological stress in the post-conception period in ewes affects fetal growth and gestation length

Fetal development can be influenced by maternal environment in the peri-conceptional period. This study investigated the effect of maternal feed intake and psychological stress within the first 6 days after conception on embryo development and fetal growth. Superovulated ewes (n=40) were artificially inseminated with semen from one ram. Ewes were then divided into four groups (n=10): group 1 (control) was fed at maintenance level, group 2 (high) at 2x maintenance, and group 3 (low) at 0.5x maintenance on days 2-6 after conception. Group 4 (stress) was fed at maintenance level and then an intense physical and psychological stress challenge was applied for 1 h only on days 2 and 3 after conception. Embryos were recovered at day 6. A total of 113 transferable grade embryos were transferred singly into synchronized untreated recipients, while the remaining embryos (n=165) were fixed and stained for cell counts. Post-conception maternal stress or feed intake did not alter the cell count or grade of day 6 embryos. Fetuses from the stress group had longer crown-rump lengths at day 30 and longer femur length at day 58. Fetuses from the stressed and high feed groups had greater abdominal circumferences at day 85. Subsequent birth weights were not significantly different. Ewes carrying lambs from the stress treatment had shorter gestation lengths. These results show that short-term perturbations of the post-conception maternal environment have measurable effects on fetal development and gestation length.

Association of a microsatellite flanking FSHB gene with reproductive traits and reproductive tract components in pigs

Microsatellite FSHBMS polymorphism at the 5’ flanking region of &lt;I&gt;FSHB&lt;/I&gt; gene was genotyped and associations with reproductive traits in several pig populations and with reproductive tract components in the Large White × Meishan F&lt;sub&gt;2&lt;/sub&gt; offspring were studied. The results showed that FSHBMS allele 98 carriers had a non-significantly higher total number born and number born alive in multiple parities; 118/118 animals had a significantly higher number of piglets at weaning than 98/98 and 98/118 animals (&lt;I&gt;P&lt;/I&gt; &lt; 0.05) and significantly higher litter weight at weaning and individual weight at weaning than 98/98 animals (&lt;I&gt;P&lt;/I&gt; &lt; 0.05). The 98/118 animals had the shortest gestation length (&lt;I&gt;P&lt;/I&gt; &lt; 0.05); the length of uterine horns and the length of oviducts of 98/98 individuals were shorter and longer, respectively, than those with 98/118 genotype (&lt;I&gt;P&lt;/I&gt; &lt; 0.05).

Influence of pregnancy on locomotor and feeding performances of the skink, Mabuya multifasciata: Why do females shift thermal preferences when pregnant?

It has been documented in the many-lined sun skink ( Mabuya multifasciata) that pregnant females select lower body temperatures (27.6–30.8 °C) than do nonpregnant females and adult males (29.7–35.7 °C). We therefore used the skink to test the hypothesis that the maximization of reproductive benefits should be achieved in pregnant females by shifting thermal preferences towards the levels optimal for embryonic development but entailing relatively small costs of reproduction. Data on adult males showed that temperatures maximizing swimming stamina (indicative of locomotor endurance) fell within the range of body temperatures selected by nonpregnant females and adult males. Data on swimming stamina and feeding performance of pregnant females, nonpregnant females and adult males measured at 26 and 30 °C showed that: (1) pregnancy impaired locomotor and feeding performances, but such impairments did not persist after parturition; (2) the degree of locomotor impairment during pregnancy was greater at 26 °C than at 30 °C, but the degree of feeding impairment during pregnancy was greater at 30 °C than at 26 °C. Pregnant females of M. multifasciata selecting body temperatures at about 29 °C could not only produce good-quality offspring in a relatively short gestation length but also reduce reproductive costs associated with locomotor and feeding impairments to some extent. Thus, data from M. multifasciata validate the above hypothesis.

The impact of uterine infection on a dairy cow's performance

The aim of this study was to assess the predisposing factors leading to uterine infection in dairy cows and evaluate its impact on the cow's performance. Performance indicators included feed intake, milk fat and protein composition, milk yield, fertility and culling. Data were studied from 2914 completed lactations from the Holstein Friesian Langhill Dairy herd between January 1990 and August 2005. There were 402 cases of uterine infection (from 321 cows) in the Langhill herd, a level of 13.8% during the study period. Calving assistance was highly associated with the incidence of uterine infection ( χ 2 = 106.63, P < 0.001). Failure to conceive ( χ 2 = 3.89, P < 0.05; χ 2 = 11.20, P < 0.001) and culling ( χ 2 = 13.66, P < 0.001, χ 2 = 8.55, P < 0.01) were also implicated with calving assistance and uterine infection, respectively. The main predisposing factors related to an incidence of uterine infection were calving assistance, twin births, malpresented calves, and retained placenta. First-time calvers and cows with a shorter gestation length were associated with more cases of uterine infections. Additionally, lower daily dry matter intakes and milk yields during the first 100 days in milk (DIM) were associated with higher incidence levels of uterine infection. Also, a higher incidence level of uterine infection was related to lower milk protein composition from 1 to 21 DIM and a poorer body condition from 101 to 300 DIM. Cows with poorer drying off body condition scores and longer lactation lengths were associated with a higher incidence level of uterine infection. Calving assistance was associated with male and twin births, first-time calvers and cows with oversized calves. Cows with an assisted calving were also associated with an increased number of days from calving to first service. The predisposing factors influencing the occurrence of calving assistance can be influenced by suitable management to reduce the chances of oversized calves, the detrimental effects of twin births (such as calving assistance and retained placentas) and prenatal knowledge of the calf's sex. The occurrence of uterine infection can be reduced by minimising the need for assistance at calving. Assistance should only be carried out when necessary and appropriate hygiene should be used to decrease the incidence of uterine infections from intervention and involuntary culling due to cows failing to conceive.

Variability and repeatability in gestation length related to litter performance in female pigs on commercial farms

Forecasting gestation length (GL) in sows enables producers to be prepared to provide assistance at farrowing, or for timely treatment to induce parturition. The objectives of the present study were to determine GL across parities, the repeatability and correlation of the GL, and associations of GL with the three litter size variables (total pigs born, pigs born alive, and dead piglets) and longevity. This study was conducted on 94 farms and encompassed 66,254 farrowing records of 13,715 sows born during 1999. Variance components and correlation analyses were used to determine the repeatability and the correlations of GL. Mixed-effects models were used to analyze associations of GL with litter size variables and longevity. The mean of GL across parities was from 115.2 to 115.4 d. The proportions of GL 114, 115, and 116 d for all farrowing events were 19.2, 30.8, and 22.2%, respectively. The GL between parities were correlated (0.40 ≤ r ≤ 0.56; P < 0.01). The repeatability of GL was 0.50 on commercial farms. Shorter GL was associated with more numbers of total pigs born and dead piglets ( P < 0.01). Sows with GL 113 to 116 d had more pigs born alive than those with GL ≤ 112 and ≥117 d ( P < 0.01). Sows with GL ≤ 112 d were 1.57 and 2.21 times as likely to be culled as those with GL 115 d ( P < 0.01). It is recommended that swine producers maintain records of GL at each parity in individual sows.

Assessment of reproductive parameters in female Dwarf goat ( Capra hircus) on the basis of progesterone profiles

A study was undertaken to look into the reproductive performance of female Dwarf goats reared under traditional conditions at NIAB Farm, Faisalabad, Pakistan. The serum progesterone profile was used to monitor various reproductive parameters (length of postpartum period, resumption of cyclicity, gestation period, prepartum period, parturition) in two lots of goats. Litter size, birth weight of kids and kidding interval were also observed. Most of the animals conceived within 15–59 days of postpartum period. All the does conceived at first or second estrus. During gestation period, higher levels of progesterone were maintained with wide variations falling in the range of 3–13 ng ml −1. However, a few days before parturition a decline was noticed at 6 ± 0.9 days and it reached to the basal level of 0.1 ng ml −1 after the completion of parturition process. The length of gestation period was found to be 145.8 ± 5 days in the first lot and 145.2 ± 4 days in the second lot. A very short kidding interval (203.7 ± 46 days) and considerably bigger litter size (1.8 ± 0.8) was observed. All the parturitions were normal and a considerable weight gain (8.2 ± 0.3 kg) of mothers was recorded during pregnancy. The initial birth weight of kids was averaged as 2.1 ± 0.5 kg in the first and 1.6 ± 0.2 kg in the second lot. It was concluded that Dwarf goat has short gestation length, postpartum period and kidding interval along with multiple births being common. Due to these factors, its reproductive efficiency can be exploited for efficient goat meat production.

A questionnaire-based study of gestation, parturition and neonatal mortality in pedigree breeding cats in the UK

This study was based on a convenience-sampling questionnaire study of pedigree cat breeding in the UK. Data were collated for the births of 1,056 litters from 14 different pedigree breeds and 942 different households. Significant relationships between various outcomes and relevant predictors were assessed by multiple linear regression or logistic regression as appropriate. The overall mean gestation length of 65.1 days varied significantly between the breeds (P<0.0001), and larger litter sizes were associated with shorter gestation lengths (P=0.04). The mean litter size of 4.6 kittens also varied significantly according to breed (P<0.0001). The weight of kittens born alive (overall mean 93.5 g) increased with longer gestation lengths (P=0.0003), decreased with larger litter sizes (P<0.0001) and varied between the breeds (P<0.0001). A total of 8.0% of pregnancies resulted in a caesarean section, with a higher risk associated with smaller litter sizes (P=0.002). Although the frequency of caesarean sections varied from 0 to 18.5% between individual breeds, breed itself was not shown to have a significant independent effect on this likelihood. A mean of 7.2% of all the kittens were stillborn, which varied according to breed (P=0.0003), and the risk of a stillborn kitten increased with litter size (P=0.0001), and with the presence of congenital defects in the litter (P=0.0002). The mean kitten mortality between birth and 8 weeks of age was 9.1%, and the majority of these occurred in the first week of life. Parturition intervals varied widely. The duration of first stage of labour was less than 2h in 82.9% of cats. The interval between the birth of the first and last kitten was less than 6h in 85.7%, but more than 48 h in three cats. A maximum of 48 h was recorded between the births of individual kittens in unassisted deliveries.

Gregariousness increases brain size in ungulates

The brain's main function is to organise the physiological and behavioural responses to environmental and social challenges in order to keep the organism alive. Here, we studied the effects that gregariousness (as a measurement of sociality), dietary habits, gestation length and sex have on brain size of extant ungulates. The analysis controlled for the effects of phylogeny and for random variability implicit in the data set. We tested the following groups of hypotheses: (1) Social brain hypothesis-gregarious species are more likely to have larger brains than non-gregarious species because the former are subjected to demanding and complex social interactions; (2) Ecological hypothesis-dietary habits impose challenging cognitive tasks associated with finding and manipulating food (foraging strategy); (3) Developmental hypotheses (a) energy strategy: selection for larger brains operates, primarily, on maternal metabolic turnover (i.e. gestation length) in relation to food quality because the majority of the brain's growth takes place in utero, and finally (b) sex hypothesis: females are expected to have larger brains than males, relative to body size, because of the differential growth rates of the soma and brain between the sexes. We found that, after adjusting for body mass, gregariousness and gestation length explained most of the variation in brain mass across the ungulate species studied. Larger species had larger brains; gregarious species and those with longer gestation lengths, relative to body mass, had larger brains than non-gregarious species and those with shorter gestation lengths. The effect of diet was negligible and subrogated by gestation length, and sex had no significant effect on brain size. The ultimate cause that could have triggered the co-evolution between gestation length and brain size remains unclear.

Neonatal outcomes in offspring of women with anxiety and depression during pregnancy

The presence of mental disorder during pregnancy could affect the offspring. To examine the effects of anxiety disorder and depression in pregnant women on neonatal outcomes, and to compare neonatal outcomes between offspring of attendees and non-attendees in a general population-based health survey. Pregnant women (n = 680) were identified from the population-based health study of Nord-TrØndelag County (HUNT-2) by linkage with the Medical Birth Registry of Norway. The women rated themselves on the Hospital Anxiety and Depression Rating Scale (HADS). Outcome variables were gestational length, birth weight, and Apgar scores. HADS-defined anxiety disorder during pregnancy was associated with lower Apgar score at one minute (score < 8; odds ratio = 2.27; p = .03) and five minutes (score < 8; odds ratio = 4.49; p = .016). No confounders were identified. Anxiety disorder and depression during pregnancy was not associated with low birth weight or preterm delivery. Offspring of non-attendees had a lower birth weight (77 g; t = 3.27; p = 0.001) and a shorter gestational length (1.8 days; t = 2.76; p = 0.006) than that of offspring of attendees, a difference that may be explained by a higher load of psychosocial risk factors among the non-attendees. In our study that may be biased towards the healthier among pregnant women, anxiety disorder or depression during pregnancy were not strong risk factors for adverse neonatal outcomes although low Apgar score in offspring of women with anxiety disorder may indicate poor neonatal adaptation.

The effect of strain of Holstein-Friesian cow and feeding system on reproductive performance in seasonal-calving milk production systems

AbstractThree strains of Holstein-Friesian (HF) cows: high production North American (HP), high durability North American (HD) and New Zealand (NZ) were assigned, within strain, to one of three pasture-based feeding systems: Moorepark (MP), high concentrate (HC), and high stocking rate (HS). The effects of strain of HF, feeding system and parity on milk production, body condition score (BCS), live weight, energy balance and reproductive performance were studied using a repeated measures model with a factorial arrangement of strain ofHF and feeding systems. Associations between these variables and conception to first service (CONCEPT1), conception to first and second service (CONCEPTl_2), pregnancy rate at 6 weeks (PREG6) and overall pregnancy rate (PREG) were assessed using logistic regressions. When treatment means were compared, the NZ strain had a shorter gestation length and a higher CONCEPT1J2 than both the HP and HD strains. Similarly, the NZ strain had a higher PREG6 and PREG than the HP strain. Feeding system had no significant effect on reproductive performance. The HP strain had the highest milk yield at first AI and peak milk yield, the NZ strain had the lowest milk yield while the HD strain was intermediate. The energy balance of the NZ strain was higher than that of the HP and HD strains. The NZ strain had the lowest live weight and highest BCS; the HD strain had the highest live weight and the HP strain had the lowest BCS. The results show that dairy cows with superior genetic merit for fertility traits have better reproductive performance.

Reproductive performance of South African indigenous goats following oestrous synchronisation and AI

The reproductive performance following oestrous synchronisation and artificial insemination (AI) was evaluated during the natural breeding season (autumn) in 90 indigenous (Boer and Nguni) South African goats. All does were synchronised for 16 days with medroxyprogesterone acetate (MAP) followed by an IM injection of 300 IU PMSG at progestagen withdrawal. Cervical inseminations were performed at a fixed time (48 h and 60 h) with fresh diluted Boer goat semen. No significant differences between Boer and Nguni goats were recorded with respect to oestrous response (98% and 93%) and the onset of oestrus (29.1 ± 0.9 h and 30.7 ± 0.8 h), respectively. The duration of oestrus in the Nguni goats (29.9 ± 2.0 h) was significantly ( P < 0.01) shorter than in Boer goats (37.0 ± 2.1 h). Conception rates were 52% and 53%, litter size averaged 2.2 ± 0.2 and 2.0 ± 0.2 and the gestation period an average of 148.6 ± 0.9 days and 149.1 ± 0.8 days for Boer and Nguni goats, respectively, these differences being non-significant. Does with quadruplets had a significantly ( P < 0.05) shorter gestation length (142.7 ± 2.1 days) than does with singles, twins and triplets (150.0 ± 0.9 days, 148.8 ± 1.0 days and 150.0 ± 1.1 days, respectively). The mean kid birth weight was 2.7 ± 0.5 kg with males being (2.8 ± 0.1 kg) significantly ( P < 0.05) heavier than females (2.5 ± 0.1 kg) and crossbred kids (2.9 ± 0.1 kg) significantly ( P < 0.01) heavier than pure Boer goat kids (2.4 ± 0.1 kg). Kid birth weight decreased with an increase in litter size, resulting in all birth weights for singles, twins, triplets and quadruplets being significantly ( P < 0.01) different from each other (3.6 ± 0.4 kg, 3.1 ± 0.5 kg, 2.3 ± 0.6 kg and 1.6 ± 0.3 kg, respectively). The overall neonatal loss rate within 48 h postpartum was 22.2%, which increased significantly with an increase in litter size and was significantly ( P < 0.01) higher for Boer goats (34.2%) than for crossbred kids (12.7%). The results indicate that oestrous synchronisation with progestagen is efficient and the duration of the induced oestrus is shorter in Nguni does than in Boer goat does. The conception rates obtained following oestrous synchronisation and AI were, however, very low and this aspect needs more attention. Litter size reduces birth weight and survival rate of indigenous South African goat kids.

Human Prenatal Investment Affected by Maternal Age and Parity

This paper investigates the effects of mother's age and parity on the prenatal allocation of resources in sons and daughters using a sample of 6994 in 20- to 34-year-old mothers from Granada (Spain). This study tests the Trivers–Willard allocation model, which predicts that, depending on the mother's condition, there can be a bias from 50/50 expected investment in the sexes. The results show that mothers of 25–29 age class produce relatively heavier sons compared to younger mothers, suggesting a bias in the allocation of resources before birth favoring neonate boys. This extra investment in boys appears to be related more to the mother's age than to her parity. Offspring of multiparous mothers had shorter gestation length, but multiparous mothers of the 25–29 age class had boys with a longer gestation than the younger ones. The 25–29 age class mothers are in the peak of fertility and they are presumably in better condition than the other mothers in the study sample. The results suggest that Granada women performed a sex-biased prenatal investment favoring sons by prolonging the gestation period. An index of boys' extra birth weight is proposed as a suitable variable to measure the maternal prenatal investment.

The association between maternal factors and perinatal outcomes in triplet pregnancies

Objective: The purpose of this study was to evaluate the associations between maternal factors and outcomes in triplet pregnancies. Study Design: This was a historic cohort study of 194 triplet pregnancies of ≥24 weeks of gestation that were delivered from 1983 through 2001 from five medical centers. Results: In analyses that were limited to pregnancies with all live-born triplets (178 pregnancies), women with a previous good outcome (>2500 g + >37 weeks of gestation) had longer gestations (+7.9 days, P =.03), better rates of fetal growth (+4.9 g/wk, P <.0001), and higher birth weights (+153 g, P <.0001). Maternal weight gains of <36 pounds by 24 weeks of gestation were associated with lower birth weights (−197 g, P <.0001), and fetal growth rates at ≤25th percentile were associated with a shorter length of gestation (−36.7 days, P <.0001). Conclusion: Previous obstetric outcome and weight gain by 24 weeks of gestation were associated significantly with fetal growth rate and birth weight; fetal growth rate, in turn, was associated significantly with length of gestation. (Am J Obstet Gynecol 2002;187:752-7.)

HOLISTIC OBSTETRICAL PROBLEM EVALUATION (HOPE): TESTING A THEORY TO PREDICT BIRTH OUTCOMES IN A GROUP OF WOMEN FROM APPALACHIA

The purpose of this study was to test the Holistic Obstetrical Problem Evaluation (HOPE) theory by determining the effects of prenatal factors from the biophysical, psychosocial, spiritual, and perceptual domains of the HOPE theory with infant birth outcomes. Face-to-face interviews were conducted using standard and reliable questionnaires with a convenience sample of 120 pregnant women between the ages of 14 and 44 years and 16-28 weeks gestation, and attending three prenatal clinics in East Tennessee. Based on the multiple regression analysis, absence of maternal partner support during pregnancy and African-American race predicted variance for infant birth weight ( p < .05), while lower levels of self-esteem, use of drugs and alcohol, and active religiosity predicted shorter length of gestation at birth ( p < .05). The multiple logistic regression analysis model revealed that the HOPE theory was significantly related to a greater incidence of preterm birth ( p = .03), Chi 2 = 28.16, R 2 = .22. Within this model, lower levels of self-esteem and a woman's negative perception of her pregnancy, were significant predictors for preterm birth ( p < .05). Although there was preliminary support for this holistic theory, further research with a larger and more diverse population of women is needed.