Hyperprolific Sows Research Articles

Nutritional interventions to prevent and rear low‐birthweight piglets

Selection for hyperprolific sows, as a means of increasing litter size and profit, has resulted in an increased number of low-birthweight (LBW) piglets. These LBW piglets might suffer from increased morbidity and mortality during the early neonatal period. In addition, they show reduced growth performance, meat and carcass quality, which leads to an important economic loss for the farmer in the post-natal period. Therefore, nutritional interventions can be undertaken to prevent and rear LBW piglets. In the first part of this review, the preventive strategies at the sow level will be discussed. Approaches in preventing LBW piglets are to optimize the intrauterine environment via supplementing the sow during gestation. In the second part of this review, the interventions at the piglet level will be described. To increase the survival and growth rates of LBW piglets, one must focus on ensuring adequate colostrum and milk intake. Interventions include supplementing piglets, split nursing, split weaning and cross-fostering. Additional interventions increasing the probability of optimal post-natal food intake will be discussed.

Effects of feeding 10% rapeseed meal (Brassica napus) during gestation and lactation over three reproductive cycles on the performance of hyperprolific sows and their litters

Quiniou, N., Quinsac, A., Crépon, K., Evrard, J., Peyronnet, C., Bourdillon, A., Royer, E. and Etienne, M. 2012. Effects of feeding 10% rapeseed meal (Brassica napus) during gestation and lactation over three reproductive cycles on the performance of hyperprolific sows and their litters. Can. J. Anim. Sci. 92: 513–524. Largely due to increased production of biodiesel, there is a greater availability of solvent-extracted rapeseed meal (RM) in France, making it competitive for feeding pigs. Nevertheless, the long-term effects of dietary glucosinolates (GSL) when feeding RM on sow reproductive and litter performance are a persistent concern to feed manufacturers. Four batches of 24 hyperprolific sows were fed to evaluate the effects of including 0 or 10% RM [14.5 µmol GLS g−1dry matter (DM) basis] in the gestation and lactation diets over three reproductive cycles. Intake of dietary GLS remained below 5 mmol d−1over the gestation period and averaged 8 mmol d−1over the lactation period, corresponding to less than 2 µmol GLS g−1DM basis. Lactation feed intake, sow body weight and backfat, and the length of the weaning-to-estrus interval were not different (P>0.05) between treatment groups. Sows fed diets with 10% or no RM farrowed 43.6 and 43.8 piglets over three reproductive cycles, respectively (P>0.05). Piglet weight at birth or weaning, survival and litter weight gain were not affected (P>0.05) by dietary RM inclusion. Similar (P>0.10) plasma thyroxin levels of sows and piglets indicated that thyroid function was not altered by RM inclusion. In conclusion, feeding gestation and lactation diets including 10% RM to hyper prolific sows over three parities was safe and did not affect sow longevity, reproductive or litter performance.

Maturation of digestive function is retarded and plasma antioxidant capacity lowered in fully weaned low birth weight piglets

The digestive function of low birth weight (LBW) pigs post-weaning has been poorly studied. Therefore, newborns from eleven hyperprolific sows were weighed, weaned at 27·2d and fed a starter diet until sampling. Sampling was done between 18 and 28d post-weaning. An LBW piglet (n 19) was defined as a piglet having a birth weight less than 1kg and less than the lower quartile of litter birth weights. Normal birth weight (NBW) piglets (n 13) were having a birth weight close to the mean litter birth weight. For each piglet, eighty-eight variables were determined. Data were analysed with linear models with type of piglet and litter as predictors. A principal component analysis was performed to determine the most important discriminating variables. In the LBW pig, the development of the digestive tract post-weaning was delayed: lower small-intestinal weight:length ratio due to a thinner tela submucosa and tunica muscularis and a higher secretory capacity, both in the distal jejunum. These observations might be a consequence of lower circulating insulin-like growth factor-1 (IGF-1) concentrations (126 (se 10·0) v. 158 (se 12·0)ng/ml for LBW and NBW, respectively) and a lower density of IGF-1 receptors in the proximal small intestine. Additionally, the plasma antioxidant capacity was lower for the LBW pig. Taken together, in the LBW piglet, the normal gut maturation post-weaning was retarded and this did not seem to be related to the weaning transition as such.

Influence of some sow characteristics on within-litter variation of piglet birth weight

Within-litter variation of piglet birth weight (BW0) is associated with an increased piglet mortality and a high variability in pig weight at weaning and weight or age at slaughter. Data collected in two experimental herds were used to quantify within-litter variability in BW0 and to assess the influence of factors mainly related to the sow. Within 24 h after birth, piglets born alive were individually weighed and stillborn piglets were collectively (first data set) or individually (second data set) weighed. The first data set was restricted to litters with no or only one stillborn piglet (3338 litters). It was used to assess the influence of genetic selection on BW0 variation by comparing litter characteristics before (1994 to 1996) and after (2001 to 2004) the development of hyperprolific sows in this herd. The second data set included all litters (n = 1596) from sows born between 2000 and 2004. For each litter, mean BW0 (mBW0) and its coefficient of variation (CVBW0) were calculated. Then, variance analyses were performed to test the influence of litter size, parity, year of sow birth and season at conception. Prolificacy improvement was associated with an increased CVBW0 in litters from pure Large White (LW) and Landrace × Large White (LR × LW) crossbred sows. The CVBW0 averaged 21% and was significantly influenced by litter size and parity. It increased from 15% to 24% when litter size varied from less than 10 piglets to more than 15 piglets. The proportion of small piglets (i.e. weighing less than 1 kg) increased concomitantly. The CVBW0 was not repeatable from a parity to the following. It was lowest for first and second parities (20%) and thereafter increased progressively. The CVBW0 was positively related to sow’s backfat thickness gain during gestation. Taking into account litter size, parity, year of sow birth and season at conception explained 20% of BW0 variation. Thus, major part of heterogeneity is due to other factors, presumably including embryo genotype, on the one hand, and factors that influence embryo and foetus development, such as epigenetic factors, on the other hand.

Effect of RYR1T Gene Polymorphism on the Initial Growth and Fattening and Slaughter Values of Polish Synthetic Line 990 Pigs Reared in Standardized Litters

The aim of this study was to determine the effect of the ryanodine receptor gene - RYR1T polymorphism on the initial growth and fattening and slaughter values of Polish Synthetic Line 990 pigs reared in standardized litters. The study was carried on 276 offspring of hyperprolific sows. The sows gave birth to at least 12 live-born piglets. On the first day after birth, litters were equalised to 12 piglets in litter. The body weight was examined on the 21st (21BW), 28th (28BW), 63rd (63BW) and 180th (180BW) days of life. During evaluation, the live average daily gain (LADG) from birth to day 180 of life and the average daily gain (ADG) from day 63 to day 180 of life were determined. The percentage meat content (PMC), backfat thickness (BFT) and loin eye thickness (LET) was determined using PIGLOG 105 ultrasound apparatus. Two alleles of the RYR1 gene (RYR1C, RYR1T) and three genotypes (C/C, C/T and T/T) were identified. The 21BW and 28BW of the T/T genotype were significantly lower than that of the C/C and C/T. The highest PMC was characteristic of the T/T genotype, whereas the lowest one of the C/C genotype (p ⪬ 0.05). The T/T genotype had a higher LET than the C/C genotype (p ⪬ 0.05). No significant differences with respect to LADG, ADG and BFT between RYR1 genotypes were found. It can be stated that early identification of homozygous animals with respect to the RYR1T gene may allow the prediction of the body weight of animals in the initial period of their rearing.

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.

OVARIAN AND OOCYTE CHARACTERISTICS OF HYPER- AND HYPO-PROLIFIC SOWS

Intensive breeding and genetic selection programs have resulted in a significant improvement in the reproductive efficiency of commercial pig breeds and the creation of hyperprolific pig lineages. However, the physiologic and molecular characteristics of these hyperprolific animals are not well understood. In this study we compared ovarian function and meiotic competence of oocytes collected from sows of the same breed but at the extremes of fertility. Hyper-prolific (those that had an average of ≤ 15 piglets/litter for at least 3 consecutive farrowings) and hypo-prolific (those that had an average of ≥10 piglets/litter for at least 3 consecutive farrowings) Landrace sows were identified and provided by the pig genetics company Génétiporc Inc. (St-Bernard, QC, Canada). The females (n=32) were slaughtered and ovaries collected and transported to the laboratory in physiological saline (0.9%) at 30–35 °C. The number of corpora lutea, small follicles (<3mm) and large follicles (≤3mm) were counted. Oocytes were separately aspirated from small- and largefollicles, and maturated in vitro under standard conditions for 44–46 hr. After maturation, cumulus cells were removed and oocytes selected by the presence of the first polar body, indicating successful meiotic maturation. Hyper-prolific sows had a significant higher average of corpora lutea (23.3±0.9 vs. 19.0±1.0) compared to hypo-prolific sows. The average number of large (44.7±3.2 vs. 38.4±3.7), small (33.6±1.5 vs. 35.6±4.1), and total follicles (77.0±3.7 vs. 75.3±7.0) per sow was similar between hyper- and hypo-prolific females. The meiotic maturation rates of oocytes derived from small (46.8% vs. 42.8%) and large follicles (70.9% vs. 72.8%) were also similar between hyper- vs. hypo-prolific females. This suggests that oocytes from hyper- and hypo-prolific sows have similar capacity to complete meiotic maturation. The number of corpora lutea indicates that hyper-prolific sows can, on average produce 4.3 more oocytes per ovulation than do the hypo-prolific animals. However, this difference is not sufficient to explain the average higher number of piglets per farrowing. Additional studies are underway to further investigate follicular and embryonic characteristics of hyper- and hypo-prolific animals from the same genetic lineage. Supported by a NSERC Strategic Gant to BDM, MFP and VB. (poster)

Feeding behavior in primiparous lactating sows: Impact of a high-fiber diet during pregnancy1

Voluntary feed intake of hyperprolific sows can be insufficient to cover the requirements for milk production and maintenance of body condition. A bulky diet fed during pregnancy is known to prepare sows for an ad libitum feed supply after parturition as shown by the increased feed intake during lactation. The aim of this study was to investigate the feeding behavior of young sows during their first lactation to evaluate the further impact of the feeding experience acquired during pregnancy, through the addition of dietary fiber in the diet. Analysis of the feeding pattern and the profile of feed intake tested the hypothesis that lactating sows would exhibit different feeding strategies depending on the diet during pregnancy. During pregnancy, 24 primiparous sows (Large White x Landrace) were offered either 2.4 kg of a control diet/d containing 3.16% crude fiber or 2.8 kg of a high-fiber diet/d containing 12.42% crude fiber. All sows received 33 MJ of DE/d. From the first day postpartum until weaning, all sows were offered the same lactation diet ad libitum. The feeding pattern during lactation was recorded as ADFI, meal frequency, and meal size. In lactation, the ADFI did not differ according to the treatment. Compared with control sows, high-fiber sows consumed their diet in more (P < 0.05) but smaller meals (P < 0.05). In both treatments, ADFI and the number of daily meals increased over weeks of lactation (P < 0.001). All sows presented a strong diurnal and bimodal feeding activity evolving toward 2 distinct feeding periods occurring from 0500 to 0900 and from 1400 to 1800 and accounting for 0.64 of the total daily feed intake during the third week of lactation. The provision of a fibrous diet during pregnancy pointed out the role of an early feeding experience on the development of feeding behavior during the first reproductive cycle.

Factors associated with stillborn and mummified piglets in high-prolific sows

Stillbirth concerns about 2.5 million piglets each year in France and is expected to worsen in the coming years, due to hyperprolific sows. The present study was performed to determine the risk factors of the presence of stillborn piglets or mummies in the litter using data from three ex- perimental herds. From June 1999 until June 2000, sow, stillborn and mummy characteristics were closely recorded around farrowing. Information was recorded on 455 litters, from 308 sows. After se- lection, a total of 447 litters, originating from 302 crossbred (Large White × Landrace) sows were used. Two hundred and fifty-five litters had no stillborn. Neither individual piglet body weight nor variability of piglet body weight within litters were found to influence stillbirth. A reduction in the av- erage litter or sow live weights increased the probability of having a stillbirth. When a full litter was born with a human presence, the proportion of litters without a stillborn was higher than in cases of partial supervision (65.7 vs. 4.5 to 45.6%). At the same time, the number of litters with two or more stillborn piglets was lower (11.2 vs. 23.6 to 30.9%). Only 46% of the litters had no stillborn when no supervision was performed. These results indicate that good supervision (more than 75% of births with a human presence) decreased stillbirth in pigs, while individual piglet weight did not alter it. A reduction in litter live weight decreased the risk of having mummies, whereas an increased litter size had the opposite effect. sow / parturition / stillbirth / mummies / risk factors / supervision

Follicular growth and maturation in hyperprolific and large white sows.

The mechanisms whereby hyperprolific sows achieve their increased ovulation rate (+5 oocytes on average) compared with normal Large White sows were explored in this study. The following specific questions were asked. Is increased ovulation rate related to 1) increased follicular populations within the ovaries or 2) alterations in terminal follicular growth and maturation? The population of antral follicles in six sows of each genotype was studied using histological techniques on ovaries obtained at the preovulatory stage. No difference between the total number of antral follicles, number of healthy or atretic follicles in specific size classes, and in size of the preovulatory follicles could be detected. The number of granulosa cells contained in preovulatory follicles was also similar between genotypes. Terminal follicular growth and maturation were studied in 15 sows of each genotype killed at d 1, 3, or 5 (n = 5.d-1.genotype-1) after the end of Regumate administration (d 0). Small (< or = 3.5 mm) follicles were counted, and follicles > 3.5 mm were dissected, measured, and incubated in vitro. Steroid concentrations (estradiol and testosterone) in culture medium were then measured. The two genotypes differed in the patterns of growth of their ovulatory follicles, because at d 3 all ovulatory follicles were obvious in Large White sows. In contrast, between d 3 and 5, seven additional ovulatory follicles grew in hyperprolific sows. Differences in follicular maturation between genotypes were also detected. Whereas testosterone concentrations in culture medium were similar in the two genotypes, estradiol concentrations were markedly (P < .01) increased in hyperprolific follicles. This indicates that these follicles may have an increased aromatizing ability. How this generates the altered pattern of follicular growth and the increased ovulation rate of hyperprolific sows remains to be established.

Results of a so-called « hyperprolific line » used in pure and cross-breeding

born — and on their granddaughters (sired by H. boars). In experiment 1, ovulation rate was higher for H X LW than for LW X LW females (16.3 against 14.5, p < 0.01), but no significant difference was found for the number of embryos at one month of gestation. Conversely, H X FL showed no superiority over crossbred LW X FL in ovulation rate (15.4 against 15.2) but a higher number of embryos (11.2 against 10.4, p < 0.10). In experiment 2 the progeny of hyperprolific sows did not significantly differ from the controls in the first litter but showed an advantage of 2.4 piglets born (p < 0.01) in the second litter. Altogether the results suggest that there is an antagonism between ovulation rate and embryo survival in gilts but less in sows. Thus, by increasing the ovulation rate, a gain in litter size may only be obtained in sows.