Partitioning components of maternal growth to determine efficiency of feed use in gestating sows

Animal board invited review: Factors affecting the early growth and development of gilt progeny compared to sow progeny

Progeny born to primiparous sows farrowing their first litter, often called gilt progeny (GP), are typically characterised by their poorer overall production performance than progeny from multiparous sows (sow progeny; SP). Gilt progeny consistently grow slower, are born and weaned lighter, and have higher postweaning illness and mortality rates than SP. Collectively, their poorer performance culminates in a long time to reach market weight and, ultimately, reduced revenue. Due to the high replacement rates of sows, the primiparous sow and her progeny represent a large proportion of the herd resulting in a significant loss for the pig industry. While the reasons for poorer performance are complex and multifaceted, they may largely be attributed to the immature age at which gilts are often mated and the significant impact of this on their metabolism during gestation and lactation. As a result, this can have negative consequences on the piglet itself. To improve GP performance, it is crucial to understand the biological basis for differences between GP and SP. The purpose of this review is to summarise published literature investigating differences in growth performance and health status between GP and SP. It also examines the primiparous sow during gestation and lactation and how the young sow must support her own growth while supporting the metabolic demands of her pregnancy and the growth and development of her litter. Finally, the underlying physiology of GP is discussed in terms of growth and development in utero, the neonatal period, and the early development of the gastrointestinal tract. The present review concludes that there are a number of interplaying factors relating to the anatomy and physiology of the primiparous sow and of GP themselves. The studies presented herein strongly suggest that poor support of piglet growth in utero and reduced colostrum and milk production and consumption are largely responsible for the underperformance of GP. It is therefore recommended that future management strategies focus on supporting the primiparous sow during gestation and lactation, increasing the preweaning growth of GP to improve their ability to cope with the stressors of weaning, selection of reproductive traits such as uterine capacity to improve birth weights and ultimately GP performance, and finally, increase the longevity of sows to reduce the proportion of GP entering the herd.

Effects of increasing standardized ileal digestible lysine during gestation on reproductive performance of gilts and sows

Limited information is available on lysine requirement estimates of modern, high-producing gestating sows Therefore, the objective of this study was to evaluate the effects of increasing standardized ileal digestible (SID) lysine during gestation on piglet birthweight and reproductive performance of gilts and sows. A total of 936 females (498 gilts, 438 sows; Camborough®, PIC, Hendersonville, TN) were group-housed (approximately 275 females per pen) and individually fed with electronic sow feeders. Females were moved from the breeding stall to pens on d 4 of gestation and allotted to one of four dietary treatments on d 5. Dietary treatments included increasing SID lysine intake (11.0, 13.5, 16.0, and 18.5 g/d). Gilts (parity 1) and sows (parity 2+) received 2.1 and 2.3 kg (22.2 and 24.3 MJ net energy per day) of feed throughout the entire gestation period, respectively. Dietary treatments were achieved by different blends of low (0.48% SID lysine) and high (0.88% SID lysine) lysine diets, prepared by changing the amount of corn and soybean meal in these two diets. Female weight and backfat were recorded on d 4 and 111 of gestation. Individual piglet weight was obtained within 12 h of birth on litters from 895 females. Final weight, and calculated maternal BW, body lipid, and body lean at d 111 of gestation increased (linear, P < 0.01) for gilts and sows as SID lysine increased. There was no evidence for differences in final backfat depth. Average total born for gilts and sows was 15.3 and 16.0 pigs with no evidence for differences among treatments. The percentage of pigs born alive increased (P = 0.01) with increasing SID lysine intake for sows, but not in gilts as a result of a treatment by parity group interaction (P = 0.04) for percentage of stillborn pigs. Increasing SID lysine intake during gestation did not affect the percentage of mummified fetuses, total born, or birthweight of piglets born alive in this study. In addition, increasing SID lysine intake during gestation did not affect subsequent reproductive performance. In conclusion, increasing dietary SID lysine intake in gestation increased female BW, without changing backfat depth. The minimal effects on female reproductive performance and piglet birthweight suggest that 11 g/day of SID lysine intake appears to be adequate for gestating gilts and sows; however, providing sows with 18.5 g/d SID lysine reduced (P = 0.01) stillbirth rate by 2.3 percentage points.

Effects of timing and size of meals prior to farrowing on sow and litter performance

A total of 727 mixed parity (µ = 3.8) sows were used to evaluate the effects of timing and size of meals before farrowing on sow and litter performance. Upon entry to the farrowing house (day 113), sows were blocked by weight within parity and allotted to one of three three feeding management strategies until farrowing: (1) 2.7 kg lactation diet (1.15% standardized ileal digestible lysine and 2,153 kcal/kg net energy) once daily at 0700 hours; (2) four daily meals of 0.67 kg (0100, 0700, 1300, and 1900 hours); (3) ad libitum lactation diet and encouraged to consume feed at 0100, 0700, 1300, and 1900 hours. After farrowing, all sows were provided lactation diets fed on an ad libitum basis until weaning. Data were analyzed for treatment effects within parity category in a mixed model with block as a random effect. Feeding sows ad libitum before farrowing tended to reduce sow body weight (BW) loss (P = 0.077) and reduce backfat (BF) loss (P = 0.003) from entry into the farrowing house until weaning compared with sows fed four daily meals, with sows fed once daily intermediate. Litter gain from 24 h to weaning tended to be greater (P = 0.073) in sows fed on an ad libitum basis or four times daily prior to farrowing compared with sows fed one meal. Piglet weaning weight increased (P = 0.050) in sows fed on an ad libitum basis before farrowing, compared with those fed one meal, with those fed four times daily intermediate. There was no evidence for difference in farrowing duration, stillborn rate, colostrum yield, or 24 h piglet survival regardless of treatment. However, from 24 h after farrowing to weaning, sows fed one daily meal prior to farrowing had an increased (P = 0.012) percentage of fall-behind pigs compared with sows fed on an ad libitum basis, and increased (P = 0.027) preweaning mortality compared with sows fed four daily meals, resulting in reduced (P = 0.006) weaned percentage compared with sows fed four daily meals. There was no evidence for difference (P > 0.10) in subsequent reproductive performance regardless of treatment. In conclusion, when sows were fed on an ad libitum basis from 2 to 3 d, before farrowing there was an observed improvement in sow BW and BF maintenance during lactation, and piglet weaning weight during lactation. Increased frequency of meals prior to farrowing improved the survival of pigs to weaning compared with sows fed a single meal prior to farrowing.

Exploration of individual variability to better predict the nutrient requirements of gestating sows1

Sows often receive the same feed during gestation even though their nutrient requirements vary during gestation and among sows. The objective of this study was to report the variability in nutrient requirement among sows and during gestation, in order to develop a precision feeding approach. A data set of 2,511 gestations reporting sow characteristics at insemination and their farrowing performance was used as an input for a Python model, adapted from InraPorc, predicting nutrient requirement during gestation. Total metabolizable energy (ME) requirement increased with increasing litter size, gestation weeks, and parity (30.6, 33.6, and 35.5 MJ/d for parity 1, 2, and 3 and beyond, respectively, P < 0.01). Standardized ileal digestible lysine (SID Lys) requirement per kg of diet increased from weeks 1 to 6 of gestation, remained stable from weeks 7 to 10, and increased again from week 11 until the end of gestation (P < 0.01). Average Lys requirement increased with increasing litter size (SID Lys: 3.00, 3.27, 3.50 g/kg for small, medium and large litters, P < 0.01) and decreased when parity increased (SID Lys: 3.61, 3.17, 2.84 g/kg for parity 1, 2, and 3++, P < 0.01). Standardized total tract digestible phosphorus (STTD-P) and total calcium (Total-Ca) requirements markedly increased after week 9, with litter size, and decreased when parity increased (STTD-P: 1.36 vs. 1.31 g/kg for parity 1 and parity 3 and beyond; Total-Ca: 4.28 vs. 4.10 g/kg for parity 1 and parity 3 and beyond, P < 0.01). Based on empirical cumulative distribution functions, a 4-diets strategy, varying in SID Lys and STTD-P content according to parity and gestation period (P1 from weeks 0 to 11, P2 from weeks 12 to 17), may be put forward to meet the requirements of 90% of the sows (2 diets for multiparous sows: P1: 2.8 g SID Lys/kg and 1.1 g STTD-P/kg; P2: 4.5 g SID Lys/kg and 2.3 g STTD-P/kg; and 2 diets for primiparous sows: P1: 3.4 g SID Lys/kg and 1.1g STTD-P/kg; P2: 5.0 g SID Lys/kg, 2.2 g STTD-P/kg). Better considering the high variability of sow requirement should thus make it possible to optimize their performance whilst reducing feeding cost and excretion. Feeding sows closer to their requirement may initially be achieved by grouping and feeding sows according to gestation week and parity, and ultimately by feeding sows individually using a smart feeder allowing the mixing of different feeds differing in their nutrient content.

A cooperative study assessing reproductive performance in sows fed diets supplemented with organic or inorganic sources of trace minerals

Sows from three university research facilities (n = 245) were stratified by parity and initial body weight (BW), and within outcome groups, randomly assigned to fortified corn- and soybean meal-based control or organic trace mineral-supplemented, gestation (3,339 kcal/kg ME; 0.62% standradized ileal digestible [SID] lysine), and lactation (3,374 kcal/kg ME; 0.97% SID lysine) diets. Control gestation and lactation diets were supplemented with inorganic trace minerals (120 ppm Zn from ZnO, 30 ppm Cu from CuSO₄, and 50 ppm Mn from MnSO₄), and the experimental diets contained the same total level of minerals but complexed organic trace minerals replaced 50% of the inorganic trace minerals. Sows were fed to condition during gestation and on an ad libitum basis during lactation. Sow BW (breeding, d 110 of gestation, 48 h post-farrowing, and weaning) and feed consumed were recorded. During gestation, control sows tended to gain less weight (60.4 vs. 64.6 kg, P = 0.06) and consumed less feed (263.5 vs. 264.8 kg, P = 0.05), and had poorer Gain:Feed (G:F) (0.27 vs. 0.29, P = 0.04) than sows fed the organic trace minerals. Sow average daily feed intake (ADFI) during lactation was similar (P = 0.28) between groups (4.93 vs. 4.74 kg for control and treated sows, respectively). Number of pigs born alive (11.4 vs. 10.9, P = 0.24) and weaned (10.2 vs. 9.8, P = 0.18), and pig pre-weaning average daily gain (ADG) (0.27 vs. 0.27 kg/d, P = 0.77) and mortality (13.1 vs. 12.9%, P = 0.92) were similar for control and treated sows, respectively. Results of the current study demonstrate that sows fed diets supplemented with organic trace minerals displayed similar reproductive performance, but improved weight gain and G:F during gestation compared with sows fed inorganic trace minerals.

Effects of dietary arginine supplementation in pregnant mares on maternal metabolism, placental structure and function and foal growth

Foals born to primiparous mares are lighter and less mature than those born to multiparous dams. Factors driving this difference are not totally understood. Using 7 multiparous and 6 primiparous standardbred mares, we demonstrated that, in late gestation, primiparous mares were less insulin resistant compared to multiparous mares, and that their foals had reduced plasma amino-acid concentrations at birth compared to foals born to multiparous mares. Vascular development, as observed through structure and gene expression, and global DNA methylation were also reduced in primiparous placentas. Another group of 8 primiparous mares was orally supplemented with L-arginine (100 g/day, 210d to term). L-arginine improved pregnancy-induced insulin resistance and increased maternal L-arginine and L-ornithine plasma concentrations but foal plasma amino acid concentrations were not affected at birth. At birth, foal weight and placental biometry, structure, ultra-structure and DNA methylation were not modified. Placental expression of genes involved in glucose and fatty acid transfers was increased. In conclusion, maternal insulin resistance in response to pregnancy and placental function are reduced in primiparous pregnancies. Late-gestation L-arginine supplementation may help primiparous mares to metabolically adapt to pregnancy and improve placental function. More work is needed to confirm these effects and ascertain optimal treatment conditions.

Effect of parity and stage of gestation on growth and feed efficiency of gestating sows

The effects of parity and stage of gestation on female growth criteria, and reproductive performance were evaluated on a commercial sow farm. A total of 712 females (Camborough, PIC, Hendersonville, TN) were group-housed and individually fed with electronic sow feeders. Gilts (parity 1) and sows were offered 2.0 and 2.26 kg of feed per day (4.7 and 5.3 Mcal NE per day), respectively. Females were moved from the breeding stall to pens on day 5 of gestation. A scale was located in the alleyway after sows left individual feeding stations. Feed intake and BW were recorded daily throughout gestation generating values for ADFI, ADG, and G:F for each sow. Data were divided into 3 parity groups: 1, 2, and 3+ and gestation was divided into 3 periods: day 5 to 39, 40 to 74, and 75 to 109. From day 5 to 39, ADFI was decreased (P < 0.05) for parity 3+ sows compared to the other periods of gestation. Parity 2 sows, although provided the same feed allowance, had greater (P < 0.05) ADFI during the first period of gestation than parity 3+ sows. Parity 1 and 2 sow ADG increased (P < 0.05) from day 39 to 74 of gestation, then decreased (P < 0.05) from day 74 to 109 of gestation. Parity 3+ sow ADG increased (P < 0.05) in each subsequent period of gestation. Parity 1 sows had the greatest (P < 0.05) ADG in comparison to parity 2 and 3+ sows in each period of gestation. Regardless of parity group, G:F was poorest (P < 0.05) from day 5 to 39 of gestation compared with sequential periods of gestation. Parity 1 sow G:F was greater (P < 0.05) than parity 2 and 3+ sows for all periods of gestation. Backfat gain indicated that parity 1 sows maintained backfat (approximately 18 mm) while parity 2 and 3+ sows gained (P < 0.05) approximately 1 mm backfat throughout gestation. Total born was greatest (P < 0.05) for parity 3+ sows with parity 1 sows marginally greater (P < 0.10) than parity 2 sows. Although there was statistical evidence (P < 0.001) for a positive correlation between BW gain and total born in parities 1 (r = 0.23; P = < 0.001), 2 (r = 0.15; P = 0.035), and 3+ (r = 0.29; P < 0.001), these correlations are very weak. Overall, this study indicates that parity 1 sows have the greatest G:F in gestation and that there is a lack of evidence for strong correlations between feed intake, growth, and reproductive performance.