Intermittent suckling during an extended lactation period: Effects on piglet behavior1

Effects of early intermittent maternal separation on behavior, physiological, and growth performance in piglets

In pig production, the management of piglets by batch lactation due to the increase in litter sizes of sows may result in intermittent early neonatal maternal separation (NMS). We speculated that NMS may affect the piglets cognitive growth performance and health. To determine the extent of the effect, 12 litters of crossbred piglets (Large White × Duroc × Min-pig) were used in this trial. Piglets in the control (Con) group (n = 6) were given a standard feeding method during lactation. Piglets in the experimental group (n = 6) were subjected to the NMS model, in which sows were led out of the enclosure with food every day (8:00-11:00 and 13:00-16:00) starting from postnatal day (PND) 7. During the separation, the piglets were supplemented with milk. All experimental piglets were weaned on PND 35. The piglets were observed for aggression, play, mutual sniffing, and exploratory behavior on PNDs 7, 8, 21, 22, 34, 35, 38, 39, 51, 52, 64, and 65. Physiological indicators, namely serum adrenaline, cortisol, interleukin (IL)-1β, IL-4, IL-6, and tumor necrosis factor (TNF)-α were measured on PNDs 35, 38, and 65, while piglet growth performance was evaluated during suckling and 1 month after weaning. The results showed that aggressive behavior in the MS group was significantly higher than that in the Con group (P < 0.05). Playful and mutual sniffing behaviors in the MS group were significantly lower than those in the Con group except for PNDs 38 and 39 (P < 0.05). Active exploratory behavior in the MS group was significantly higher than that in the Con group on PNDs 7 and 8, and PNDs 21 and 22 (P < 0.05). The frequency of belly-nosing behavior was significantly higher in the MS group than that in the Con group except for PNDs 64 and 65 (P < 0.05). Compared with the Con group, epinephrine, IL-1β, IL-6, and TNF-α concentrations on PNDs 35, 38, and 65 were significantly increased in the MS group (P < 0.01), while IL-4 concentration was significantly decreased (PND 35: P < 0.05; PNDs 38 and 65: P < 0.01). Compared with the Con group, the piglet diarrhea rate in the MS group during suckling was significantly increased (P < 0.01), the weaning weight was significantly decreased (P < 0.05), and it had no significant effect on the body weight at the end of the trial (P > 0.05). In conclusion, the early intermittent NMS created stress and affected the growth performance of piglets during suckling. However, the growth rate was improved by compensatory measures during late weaning.

Impact of sow lactation feed intake on the growth and suckling behavior of low and average birthweight pigs to 10 weeks of age

Improved genetics in commercial pig production have resulted in larger litter sizes. However this has increased the prevalence of compromised pigs exhibiting inferior birthweights, weaning weights, and lifetime performance. This study aimed to determine the effects of increased sow lactation feed intake on growth of low and average birthweight piglets until 10 wk of age. Low (Low BW; <1 kg) and average (Av BW; 1.3–1.7 kg) birthweight animals were reared in uniformly weighted litters comprising 14 piglets on a foster mother offered either a low (Low FA; max 7.5 kg/d) or high (High FA; max 11 kg/d) feed allowance over a 28- ± 1-d lactation. Piglet performance was monitored from birth until 10 wk of age. Sows offered a High FA consumed 42.4 kg more feed on average than those offered Low FA, resulting in a greater derived milk yield (P < 0.05). Animals of Av BW remained heavier than Low BW pigs throughout the trial (P < 0.05). Piglets reared by High FA sows were heavier at weeks 3, 4, 5, and 7 (P < 0.05) but not week 10 (P > 0.05). Growth rate of piglets relative to their birthweight was significantly greater for Low BW piglets than those of Av BW during lactation (P < 0.001). Piglets reared by sows offered a High FA expressed greater relative growth preweaning (P < 0.05); however, postweaning relative growth for piglets reared on sows offered a Low FA was greater (P < 0.05) suggesting compensatory growth. Neither birthweight nor sow feed allowance significantly affected preweaning mortality (P > 0.05). However, Low BW animals on sows with a High FA recorded half the preweaning mortality of Low BW pigs on sows with a Low FA. During week 1 of lactation, Av BW litters recorded a greater total suckling duration compared to Low BW litters (P < 0.05) but there was no difference in suckling frequency (P > 0.05). During week 3 of lactation, High FA litters displayed a significantly lower suckling frequency (P < 0.05) yet a greater total suckling duration (P < 0.001). Average daily gain was greater for Av BW pigs during weeks 4–7 (P < 0.001) but no difference was recorded between weeks 7 and 10 (P > 0.05). Average daily feed intake was greater for Av BW pigs throughout the nursery period (P < 0.05) but feed–conversion ratio did not differ compared to Low BW pens (P>0.05). In conclusion, offering sows a High FA increased weaning weight of all animals; however, birthweight was the major determinant of postweaning performance.

Gastrointestinal tract (gut) health in the young pig

An optimally functioning gastrointestinal tract (GIT) clearly is of importance to the overall metabolism, physiology, disease status and performance of pigs of all stages of growth and development. Recently, the 'health' of the GIT ('gut health') has attracted much attention despite the lack of a clear definition to the term or its aetiology, although in broad terms, 'gut health' encompasses a number of physiological and functional features including nutrient digestion and absorption, host metabolism and energy generation, a stable and appropriate microbiota/microbiome, defence mechanisms including barrier function and mucosal immune mechanisms, and the interactions between these components. 'Gut health' in the newly-weaned (young) pig is of obvious interest due to changes in GIT structure and function associated with the post-weaning transition, and more recently to the upsurge in interest in different feed additives as dietary alternatives/replacements caused by bans/reductions in certain antimicrobial compounds being available in some parts of the world. In the presence of enteric disease(s) after weaning, a deterioration in 'gut health' may be synonymous to the overall health of the pig, and although some direct relationships can be drawn between pig performance and efficiency and a 'healthy' GIT, sometimes this connection is subtler and less obvious, especially in the absence of overt enteric disease(s). The factors and conditions involved in 'gut health' are multifactorial, complex, often poorly described and sometimes incorrectly interpreted, although it is evident that perturbations of the GIT can cause an imbalance and disturb the generalized homeostasis. In addition to any enteric diseases or conditions that might arise as a result of these disturbances, other influences will also impact such as the responses occurring in the GIT in the period immediately after weaning, any changes that might occur after a change in diet, and (or) disruptions to meal patterns and hence the flow of nutrients. Ultimately, 'gut health' represents the outcome of the GIT in response to its capacity and ability to respond and adapt to the insults and challenges it encounters.

Effects of dietary supplementation of Saccharomyces cerevisiae fermentation product to sows and their offspring on growth and meat quality

This study evaluated the effects of long term dietary supplementation of Saccharomyces cerevisiae fermentation product (SCFP) in the diets for sows and offspring on growth performance, intestinal morphology, volatile fatty acid production, and carcass characteristics of offspring. Newly weaned pigs (n = 256) were allotted to 4 treatments based on a 2 × 2 factorial arrangement. Each treatment had 8 pens with 8 pigs per pen. First factor was maternal dietary effects (no SCFP, or SCFP at 12.0 and 15.0 g/d through gestation and lactation, respectively) and the second factor was dietary supplementation of SCFP to offspring (no SCFP, or SCFP at 0.2 and 0.1% for nursery and finisher, respectively). Pigs were on a 6-phase feeding program with assigned diets from nursery to slaughter. Body weights (BW) and feeder weights were measured at the end of each phase. On d 5 after weaning, 1 pig per pen was euthanized to evaluate intestinal morphology and volatile fatty acid production. At 115 kg of BW, 1 pig from each pen was slaughtered to measure carcass characteristics. Feeding diets with SCFP to sows or to their offspring had no effect on BW, overall average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed (G:F) ratio during the nursery or finisher period. Feeding SCFP to sows tended to increase (P = 0.098) cecal butyric acid production in their offspring. Pigs with SCFP tended to have a greater (P = 0.084) concentration of acetic acid but a reduced (P = 0.054) propionic acid in colon digesta than pigs without SCFP regardless of maternal feeding regimen. Loin marbling scores were greater (P = 0.043) in pigs with SCFP than those without SCFP regardless of maternal feeding regimen. Overall, supplementation of SCFP in sow diets did not affect growth performance or intestinal morphology of their offspring. Supplementation of SCFP in diets of offspring from nursery to slaughter had little effect on growth performance. However, inclusion of SCFP from nursery to slaughter improved marbling score possibly by increased acetic acid and butyric acid production in the large intestine.

Intermittent suckling with or without co-mingling of non-littermate piglets before weaning improves piglet performance in the immediate post-weaning period when compared with conventional weaning

Background

In this experiment, intermittent suckling (IS) with or without the co-mingling (CoM) of piglets was studied as a method to stimulate solid feed intake and reduce post-weaning stress.

Methods

Three weaning regimes using 30 multiparous sows were compared: (1) conventional weaning (CW) (n = 10 litters), where piglets had continuous access to the sow until weaning (d 0, farrowing = d −25 relative to weaning); (2) intermittent suckling (IS) (n = 10 litters), where piglets were separated from the sow for 8 h/d starting at d −7 (relative to weaning); and (3) intermittent suckling with co-mingling (ISCo) (n = 10 litters) where IS started at d −7 and two litters were housed together during separation and then returned to their original sow. Ad libitum creep feed was available from d −17. At weaning pigs were housed in pens of 11 pigs, 27 pens in total. The ISCo treatment was divided in half to examine effects of different mixing strategies after weaning. Half of the ISCo litters were kept in familiar groups (ISCoF, familiar, n = 4) and the other half were mixed within treatment resulting in groups of unfamiliar pigs (ISCoNF, not familiar, n = 5), the same as IS (n = 9) and CW (n = 9) treatments.

Results

The ISCo piglets ate more creep feed in the week before weaning (P < 0.01), but also showed more aggressive and manipulative behaviour on first day of CoM compared with CW piglets (P < 0.05). IS with or without CoM increased exploratory and play behaviour on the first day of treatment intervention (P < 0.001) and increased sleeping behaviour on the last day of treatment intervention compared with CW (P < 0.001). Mixing strategy at weaning had an effect on performance data with the highest growth and feed intake seen in ISCoF pigs 2 to 8 d after weaning (P <0.001). IS and ISCoNF pigs also grew faster and ate more than CW pigs 2 to 8 d after weaning (P < 0.001). Post-weaning injury scores suggested reduced aggression in ISCo as evidenced by reduced redness (skin irritation) (P < 0.05), and a tendency for ISCo to have less scratches than CW (P < 0.1). The IS pigs slept the most and displayed less manipulative behaviours on the day of weaning and plasma haptoglobin levels remained low in IS pigs after weaning (P ≤ 0.01).

Conclusions

Both intermittent suckling techniques improved production indices in the immediate post-weaning period. However, the addition of co-mingling before weaning in combination with grouping familiar pigs together after weaning improved performance in an additive manner.

Intermittent Suckling Causes a Transient Increase in Cortisol That Does Not Appear to Compromise Selected Measures of Piglet Welfare and Stress

Simple Summary

This study assessed the effects intermittent suckling (IS) had on physiological and behavioral indices of piglets before and after weaning. Piglets were allocated to either a control treatment (conventional weaning) or an IS treatment (separation from the sow for 8 h per day starting the week before weaning). Apart from an initial peak in cortisol at the start of IS, piglets subjected to IS did not show physiological changes suggestive of a chronic stress response before and after weaning. The event of weaning still caused a decrease in growth rate and an increase in white blood cell parameters in both treatment groups. However, the IS piglets tended to gain more weight in the second half of the week after weaning. The results of this study suggest that short periods of separation (e.g., 8 h/day) do not appear to compromise piglet welfare over the peri-weaning period.

Abstract

This study tested the hypothesis that piglets subjected to intermittent suckling (IS) would show changes in physiological and behavioral indices indicative of compromised welfare in the peri-weaning period. A total of 21 primiparous sows and their litters were allocated to either a control treatment (n = 10) where piglets were weaned conventionally, or an IS treatment (n = 11) where piglets were separated daily from their sows for 8 h starting the week before weaning. Performance, physiological and behavioral measures were taken at various time points during the week before and after weaning. Plasma cortisol levels were higher (p = 0.01) in IS piglets 7 d before weaning. Regardless of treatment, the N:L ratio at 3 d and 7 d after weaning was higher (p < 0.05) than that at 1 d before weaning. The IS piglets ate more creep feed during lactation (p < 0.05), and there was a tendency for the IS piglets to gain more weight between 3 d and 7 d after weaning (p < 0.1). This study showed that, aside from an increase in cortisol at the start of IS, piglets subjected to IS did not display physiological or behavioral changes indicative of compromised welfare.

An opportunity to revolutionise sow management

Research in any area of animal production can provide the opportunity to change how the system operates and is managed. The reliance on having to wean lactating sows to re-mate them has limited the commercial options for sow management. The desire to limit lactation length to maximise the litters per sow per year concurrently creates major challenges for such-aged piglets weaned abruptly. These issues are discussed in the review. This management system also fails to recognise that sows have the potential to spontaneously ovulate in lactation even when housed in farrowing crates. Inhibition of luteinising hormone release is the basis of lactational anoestrus with the suckling stimulus providing the strongest afferent signal to this inhibitory system. Any management strategy that reduces this inhibition has the potential to trigger lactational oestrus. In this review, group housing of sows, boar exposure and intermittent suckling are identified as strong stimuli that can promote lactational oestrus. Removing the need to wean sows to mate them offers further opportunities to change the way lactating sows are managed. One option is a two-stage lactation system in which the sows are housed in farrowing crates for the first 10–14 days and then moved to group accommodation for the remainder of lactation. This system provides welfare benefits for the litter in the early stage of lactation and then the benefits of less confinement for the sows in later lactation. Group lactation would also lend itself to the implementation of stimuli to assist the mating of sows in lactation, such as piglet separation and/or boar exposure. It also accommodates the mating of sows that spontaneously ovulate in lactation. Removing the need to wean sows to re-mate them provides the opportunity to increase weaning age and implement a gradual weaning, helping to attenuate the post-weaning growth check and potentially limiting antimicrobial use in weaner pigs.

Timing of lactational oestrus in intermittent suckling regimes: consequences for sow fertility

Three intermittent suckling (IS) regimes were evaluated for their effects on lactational oestrus and subsequent fertility. Control sows were weaned (CW; n = 38) at d 26 ± 2 of lactation. In IS19-7D (n=40) and IS19-14D (n=42) sows, IS started at d 19 ± 1 of lactation and sows were weaned 7 or 14 d later. In IS26-7D (n=41), IS started at d 26 ± 1 of lactation and sows were weaned 7d later. During IS, sows were separated from their piglets for 10h/day. Oestrus detection was performed twice daily without a boar and ovulation was confirmed by ultrasound once a week. In IS19-7D, IS19-14D and IS26-7D, respectively, 50%, 64% and 61% of the sows showed oestrus and ovulation during IS (P>0.05), and, of the remaining sows, 100%, 93%, and 69% showed oestrus in the first week after weaning. In CW sows, 95% showed oestrus in the first week after weaning. Parity 1 sows were considerably less likely than older parities (23% vs. 68%) to show oestrus in lactation. Pregnancy rate of the first post partum oestrus (during lactation or after weaning) was 89% (CW), 92% (IS19-7D), 80% (IS19-14D) and 77% (IS26-7D) (P>0.05) and subsequent litter size was 14.5 ± 0.5, 14.5 ± 0.6, 15.3 ± 0.5 and 15.2 ± 0.8, respectively (P>0.05). Sows mated during lactation had similar pregnancy rate and litter size to those mated after weaning. Hence, ongoing lactation for the first 2-9 d of pregnancy did not negatively affect fertility. A total of 50-64% of IS sows showed lactational oestrus, regardless of the stage of lactation. Pregnancy rates and litter size were similar to control sows, and were not affected by stage of lactation at mating.

Effects of yeast culture supplementation on growth performance, intestinal health, and immune response of nursery pigs

A total of 216 weaning pigs were used in 2 experiments to determine the effects of dietary supplementation of yeast culture (YC) at different dose levels on the growth performance, nutrient digestibility, intestinal morphology, intestinal microflora, and immune response in weanling pigs and to determine whether YC can be a candidate to replace antibiotic growth promoters (AGP). In Exp. 1, 192 pigs (7.5 +/- 0.2 kg of BW) weaned at 28 d of age were randomly allotted to 6 treatments: 1) control (without AGP or YC); 2) AGP (chlortetracycline, 80 mg/kg); 3) 2.5 g/kg of YC (Diamond V XP Yeast Culture); 4) 5 g/kg of YC; 5) 10 g/kg of YC; and 6) 20 g/kg of YC. Each treatment had 8 replicated pens with 4 pigs per pen. Pigs were fed the experimental diets for 21 d. Average daily gain of pigs fed 5 g/kg of YC was greater (P < 0.05) than that of pigs in the control and other YC groups. However, there was no difference between the YC and AGP group. Pigs supplemented with 5 g/kg of YC, 10 g/kg of YC, and AGP had a greater (P < 0.01) ADFI than the control; however, G:F was not affected by treatment. Thus, 5 g/kg of YC supplementation level was chosen for Exp. 2. In Exp. 2, to elucidate the mode of action of YC, 24 nursery pigs (5.8 +/- 0.1 kg of BW; 21 d of age) were randomly allotted into 3 treatments for a 21-d trial. Treatments consisted of 1) control (without AGP or YC), 2) AGP, and 3) 5 g/kg of YC. Blood samples were collected weekly to measure CD4(+), CD8(+) percentage, and blood cytokine content. All pigs were harvested to determine treatment effects on gut microbiota, morphology, and immune function. Dietary supplementation of 5 g/kg of YC improved (P < 0.05) ADG of pigs compared with the control group, but performance of pigs fed YC was similar to those fed AGP. Pigs receiving 5 g/kg of YC had greater (P < 0.05) digestibility of DM, CP, GE, and jejunal villus height and villus height:crypt depth ratio (P < 0.05) compared with pigs fed the control diet. However, no differences in performance, digestibility, or gut morphology were observed between pigs fed YC and AGP. Gut interferon (IFN)-gamma concentrations were greater (P < 0.01) for pigs supplemented with YC compared with control pigs and pigs supplemented with AGP on d 21. However, plasma IFN-gamma concentrations were decreased (P < 0.01) in pigs supplemented with YC and AGP compared with control pigs on d 7, and CD4(+) was decreased (P < 0.01) in pigs supplemented with YC and AGP on d 14. Results indicate that dietary YC supplementation at 5 g/kg had a positive effect on growth performance of nursery pigs by improving jejunal villus height and villus height:crypt depth ratio and by modulating gut immune response. The comparable effect of 5 g/kg of YC supplementation and AGP on the growth performance of nursery pigs indicates that YC may be a good candidate as an antibiotic alternative.

Cortisol profiles in sows submitted to an intermittent suckling regime compared with that of abruptly weaned sows

The aim of this study was to monitor changes in cortisol levels in sows around the time of separation from their piglets, in two different intermittent suckling regimes, compared with that in conventionally weaned sows. Sows were either weaned at 21 days of lactation (CONT) or subjected to an intermittent suckling regime (IS) from 14 days of lactation onwards. Sows in the IS regimes were separated from their piglets for 12 h every day, either from 08:00 to 20:00 hours (IS12) or from 08:00 to 14:00 hours and 20:00 to 02:00 hours (IS6). Separation caused a transient increase in cortisol levels on the first (CONT and IS12) and second (IS12) day of separation, compared with a gradual decline from early morning when the sows were still continuously suckling. In IS6 sows, in contrast, the transient rise in cortisol levels after separation at 08:00 hours was observed on the first 3 days and also on day 7 of the IS regime. Cortisol parameters were correlated with peri-ovulatory characteristics like onset of oestrus, onset of the LH surge and time of ovulation. Onset of the LH surge was delayed in IS6 sows. In conclusion, increase in cortisol levels as a consequence of separation of sows and piglets, is an acute, incidental phenomenon in IS12 and CONT sows, but shows a repeated acute elevation in IS6 sows, possibly placing IS6 sows at a higher risk of influencing peri-ovulatory processes and developing cystic follicles.