Improving sow welfare and outcomes in the farrowing house by identifying early indicators from pre-farrowing assessment.

Poor outcomes reflect low performance during the farrowing and lactation periods and unanticipated sow removals. Since the period around farrowing has the highest risk for sow health issues, monitoring of sows in that time-period will improve both welfare and productivity. The aim of this study was to identify the most relevant risk factors for predicting poor outcomes and the implication for sow welfare. Identifying these factors could potentially enable management interventions to decrease incidences of compromised welfare or poor performance. Data from 1,103 sows sourced from two nucleus herds were recorded for a range of variables investigated as potential predictors of poor outcomes in the farrowing house. Poor outcomes (scored as binary traits) reflected three categories in a sow's lifecycle: farrowing, lactation, and removals. Univariate logistic regression was used to identify predictors in the first instance. Predictors from univariate analyses were subsequently considered together in multi-variate models. The least square means representing predicted probabilities of poor outcomes were then reported on the observed scale. Several predictors were significant across two different environments (farms) and for all three categories. These predictors included feed refusal (lack of appetite), crate fit, locomotion score, and respiration rate. Normal appetite compared to feed refusals reduced the risk of farrowing failure (13.5 vs. 22.2%, P = 0.025) and removals (10.4 vs. 20.4%, P < 0.001). Fit in the crate was significant (P < 0.001) for farrowing and lactation outcomes, and was more informative than parity. Sows with sufficient space had two to three times reduced risk of poor outcomes compared to restrictive crates relative to sow dimensions. Sows with good locomotion score pre-farrowing had two to three times less risk of farrowing failure (P = 0.025) and reduced piglet mortality (P < 0.001), weaned two piglets more relative to affected sows (P < 0.001), and were less likely to be removed before weaning (3.24 vs. 12.3%, P = 0.014). Sows with higher respiration rates had a significantly (P < 0.001) reduced risk of poor farrowing outcomes. This study demonstrated it is possible to predict poor outcomes for sows prior to farrowing, suggesting there are opportunities to decrease the risk of poor outcomes and increase overall sow welfare.

Farrowing and lactation are the most vulnerable events in sows' lifecycle with high risk of compromised health. For at-risk sows, poor health could result in an increased level of stillborn piglets, a decreased number of weaned piglets, or premature removals of sows from the herd. This can potentially be avoided by identifying at-risk sows prior to farrowing, to enable effective management interventions, thereby improving sow welfare. Several risk factors are shown to be consistent in identifying sows with compromised health or welfare across two different management systems. These risk factors are low appetite before farrowing, low respiration rate, leg problems, and the sows' fit within the farrowing crate relative to their dimensions. This study suggested that at-risk sows may be identified; altering their subsequent management and treatment could result in higher performance and reduced risk of premature removals.

Compensatory feeding during early gestation for sows with a high weight loss after a summer lactation increased piglet birth weight but reduced litter size.

Sows mated in summer produce a greater proportion of born-light piglets (<1.1 kg) which contributes to increased carcass fatness in the progeny population. The reasons for the low birth weight of these piglets remain unclear, and there have been few successful mitigation strategies identified. We hypothesized that: 1) the low birth weight of progeny born to sows mated in summer may be associated with weight loss during the previous summer lactation; and 2) increasing early gestation feed allowance for the sows with high lactational weight loss in summer can help weight recovery and improve progeny birth weight. Sows were classified as having either low (av. 1%) or high (av. 7%) lactational weight loss in their summer lactation. All the sows with low lactational weight loss (LLStd) and half of the sows with high lactational weight loss received a standard gestation feeding regime (HLStd) (2.6 kg/d; day 0-30 gestation), whereas the rest of the sows with high lactational weight loss received a compensatory feed allowance (HLComp) (3.5 kg/d; day 0-30 gestation). A comparison of LLStd (n = 75) versus HLStd sows (n = 78) showed that this magnitude of weight loss over summer lactation did not affect the average piglet or litter birth weight, but such results may be influenced by the higher litter size (P = 0.030) observed in LLStd sows. A comparison of HLStd versus HLComp (n = 81) sows showed that the compensatory feeding increased (P = 0.021) weight gain of gestating sows by 6 kg, increased (P = 0.009) average piglet birth weight by 0.12 kg, tended to reduce (P = 0.054) the percentage of born-light piglets from 23.5% to 17.1% but reduced the litter size by 1.4 (P = 0.014). A subgroup of progeny stratified as born-light (0.8-1.1 kg) or -normal (1.3-1.7 kg) from each sow treatment were monitored for growth performance from weaning until 100 kg weight. The growth performance and carcass backfat of progeny were not affected by sow treatments. Born-light progeny had lower feed intake, lower growth rate, higher G:F, and higher carcass backfat than born-normal progeny (all P < 0.05). In summary, compensatory feeding from day 0 to 30 gestation in the sows with high weight loss during summer lactation reduced the percentage of born-light progeny at the cost of a lower litter size, which should improve growth rate and carcass leanness in the progeny population born to sows with high lactational weight loss.

Feed intake and feeding behavior traits for gestating sows recorded using electronic sow feeders.

Electronic sow feeding (ESF) systems are used to control feed delivery to individual sows that are group-housed. Feeding levels for gestating sows are typically restricted to prevent excessive body weight gain. Any alteration of intake from the allocated feeding curve or unusual feeding behavior could indicate potential health issues. The objective of this study was to use data recorded by ESF to establish and characterize novel feed intake and feeding behavior traits and to estimate their heritabilities. Raw data were available from two farms with in-house manufactured (Farm A) or commercial (Farm B) ESF. The traits derived included feed intake, time spent eating, and rate of feed consumption, averaged across or within specific time periods of gestation. Additional phenotypes included average daily number of feeding events (AFE), along with the cumulative numbers of days where sows spent longer than 30 min in the ESF (ABOVE30), missed their daily intake (MISSF), or consumed below 1 kg of feed (BELOW1). The appetite of sows was represented by averages of score (APPETITE), a binary value for allocation eaten or not (DA_bin), or the standard deviation of the difference between feed intake and allocation (SDA-I). Gilts took longer to eat than sows (15.5 ± 0.13 vs. 14.1 ± 0.11 min/d) despite a lower feed allocation (2.13 ± 0.00 vs. 2.36 ± 0.01 kg/d). The lowest heritability estimates (below 0.10) occurred for feed intake traits, due to the restriction in feed allocation, although heritabilities were slightly higher for Farm B, with restriction in the eating time. The low heritability for AFE (0.05 ± 0.02) may have reflected the lack of recording of nonfeeding visits, but repeatability was moderate (0.26 ± 0.03, Farm A). Time-related traits were moderately to highly heritable and repeatable, demonstrating genetic variation between individuals in their feeding behaviors. Heritabilities for BELOW1 (Farm A: 0.16 ± 0.04 and Farm B: 0.15 ± 0.09) and SDA-I (Farm A: 0.17 ± 0.04 and Farm B: 0.10 ± 0.08) were similar across farms. In contrast, MISSF was moderately heritable in Farm A (0.19 ± 0.04) but lowly heritable in Farm B (0.05 ± 0.07). Heritabilities for DA_bin were dissimilar between farms (Farm A: 0.02 ± 0.02 and Farm B: 0.23 ± 0.10) despite similar incidence. Individual phenotypes constructed from ESF data could be useful for genetic evaluation purposes, but equivalent capabilities to generate phenotypes were not available for both ESF systems.

Serum Concentrations of AMH and E2 and Ovarian and Uterine Traits in Gilts.

Poor sow retention due to reproductive failure is a common reproductive inefficiency amongst piggeries. This shows that traditional methods of gilt selection are inadequate and a marker of reproductive success is needed. The aim of this study was to determine whether circulating levels of AMH and E2 at D80 and D160 are associated with uterine and ovarian traits at D160. Uterine weight, horn length and horn diameter were measured, and ovarian follicle counts were determined histologically. There was a negative relationship between both D80 and D160 AMH levels and D160 ovarian follicle populations. There was also a positive relationship between D80 E2 levels and uterine capacity in gilts that were pubertal at D160. The findings indicate that D80 and D160 AMH could be used to predict ovarian reserve and that D80 E2 levels may be indicative of uterine capacity in precocial gilts.

Effects of L-citrulline supplementation on heat stress physiology, lactation performance and subsequent reproductive performance of sows in summer.

Lactating sows are susceptible to heat stress (HS). Part of the thermoregulatory response to HS is to increase peripheral blood flow, which is mediated in part by the vasodilator, nitric oxide (NO). Therefore, the aim of this experiment was to determine the effect of supplementation of L-citrulline, a NO precursor, on symptoms of HS, lactation performance and subsequent reproductive performance of sows in summer. A total of 221 summer farrowing mixed parity sows were fed either a control diet or supplemented with 1% L-citrulline upon entry to the farrowing house (6 ± 1.8 days for mean ± standard deviation [SD] before farrowing) until weaning (26 ± 1.5 days). The average daily minimum and maximum temperature in the farrowing house was 21.0 ± 1.88 and 29.2 ± 3.82°C (mean ± SD). Rectal temperature, respiration rate, and plasma and urinary nitrite and nitrate (NOx) of sows were measured on the 19th day post-farrowing. Supplemental L-citrulline in the diet did not affect the number of piglets born alive, feed intake of sows, body weight or backfat thickness of sows at weaning, or litter weight gain. L-citrulline tended to reduce piglet pre-weaning mortality rate from 18.6% to 15.6% (p = 0.058). L-citrulline reduced the respiration rate of sows compared to the control diet at 17:00 hr (Time × Diet, p < 0.001); however, rectal temperature was not affected. L-citrulline tended to increase urinary NOx concentrations (127 vs. 224 µM, p = 0.057) but not plasma NOx concentrations. L-citrulline did not affect farrowing rate or number of piglets born alive in the subsequent parity. In conclusion, L-citrulline supplementation reduced respiration rate of lactating sows and reduced piglet pre-weaning mortality rate in summer. Whether the effects were due to a NO-dependent mechanism requires further validation.

Anti-Müllerian hormone and Oestradiol as markers of future reproductive success in juvenile gilts.

There is a need for an early marker for reproductive success in gilts as the traditional process for selecting breeding females is inefficient. There is evidence that circulating anti-Müllerian hormone (AMH) is indicative of ovarian reserve, antral follicle populations, gonadotropin responsiveness and fertility in various species other than the pig. Additionally, oestradiol (E2) has been shown to mark antral follicle populations in cattle and pregnancy outcomes in women, after gonadotropin treatment. The aims of this study were to determine whether 1) serum levels of AMH or E2, prior to or after gonadotropin injection at 60, 80 or 100 days of age, and 2) hormonal changes in response to gonadotropin stimulation (i.e. declining, plateauing or increasing hormone levels), are associated with future reproductive success in juvenile gilts. Serum samples were obtained at 0, 2 and 4 days after injection and mating and litter data were collected until parity three. Results showed that, regardless of age group and parity, Day 0 E2 levels were positively associated with the probability of stillbirth (P = 0.035) and E2 levels on Day 0 (P = 0.032), Day 2 (P = 0.045) and Day 4 (P = 0.019) were negatively associated with the number of piglets born alive. Further, both a single measurement of serum AMH levels at Day 2 (P = 0.048) and the AMH response type were associated with gestation length (P = 0.012). These findings suggest that serum AMH and E2 levels can be used to inform the selection of gilts for the breeding herd.