Sow performance and maternal behaviour in organic and conventional herds

Abstract

The study evaluates the first three parities of 144 Swedish Landrace×Yorkshire sows from three certified organic and three conventional commercial piglet-producing herds. Sows and litters were weaned at seven and five weeks post partum (pp) in organic and conventional herds, respectively. Herdsmen judged sow behaviour and maternal ability at farrowing, two weeks pp and at weaning. Herdsmen collected registrations of litter size, litter weight and sow fat status at farrowing and at weaning. Piglet mortality and oestrous signs were registered continuously during the nursing period. Sows in organic herds were scored to be more cautious among piglets, and to have better nursing behaviour and maternal ability in early lactation than sows in conventional herds. Piglet mortality was higher in organic than in conventional herds. Oestrus during lactation was only observed among sows in organic herds, and sows showing oestrus during lactation were fatter at weaning.     

Welfare and production implications of teeth clipping and iron injection of piglets in outdoor systems in Scotland

To assess the merits of implementing piglet husbandry tasks in outdoor systems, 550 piglets in 49 litters were used in a split-plot experiment to determine the effects of (a) leaving piglet teeth intact or clipping them at birth in alternate litters, and (b) injecting alternate piglets within each litter with 200 mg of iron (as dextran) at 2–4 days after farrowing or leaving piglets untreated. Leaving teeth intact increased facial lesion scores at 7 days, 14 days and weaning (22 days) but had no effect on survival or daily liveweight gain. No udder damage was recorded on sows and no behavioural differences in time spent away from the farrowing hut or willingness to be suckled were observed. Administration of iron resulted in a small but significant elevation in piglet blood haemoglobin level at weaning, but had no significant effect on piglet performance. All piglets had blood haemoglobin levels in excess of 6 g 100ml⁻¹. A survey of 90 other untreated piglets from nine different herds in northeastern Scotland failed to detect any anaemic piglets. There was no overall correlation between herd mean haemoglobin level and soil iron content, although the lowest levels of both occurred in the same herd. Implementation of these husbandry tasks is seldom likely to be justified in outdoor systems in northeastern Scotland.     

Reproductive performance in gilts through their first two parities

Fertility data were collected for 766 gilts from 12 breeding and commercial herds. The age at first breeding was 244.5 days and at first farrowing 363.2 days. The litter size was 9.91 piglets born (9.16 live). The farrowing rate at the first service was 87.8%. The total farrowing rate was 95.5% of the mated gilts and 88.4% of all the gilts. 9.8% were repeat breeders. 2.6% of the once mated gilts never returned to oestrus and still did not farrow. The culling rate was 11.6%. The major reason for culling was delayed puberty/anoestrus (7.7%). Of the 565 gilts having a first litter 85.3% were mated after weaning. The age at second farrowing was 541.7 days. The litter size was 10.9 piglets born (10.3 live). The farrowing rate after first service was 83.0%. The total farrowing rate of the 482 sows was 92.9% and of the 565 weaned sows 79.3%. 12.2% were repeat breeders. 4.8% of the sows once mated never returned to oestrus and still did not farrow. The culling rate was 20.7%. Culling because of anoestrus was 4.4%. The month of birth significantly influenced the number of gilts culled because of anoestrus, the age at first breeding and at first and second farrowing. The season also influenced the interval from weaning to service, the percentage of sows served within 7 days of weaning and culled because of anoestrus. No correlation between a high ultrasonic index and lowered fertility was found. The age at first breeding was 1.12 days younger per unit higher ultra-sonic index.     

Preventing transmission of Sarcoptes scabiei var. suis from infested sows to nursing piglets by a prefarrowing treatment with doramectin injectable solution

Studies were conducted at swine facilities in Illinois and North Carolina to evaluate the effect of treatment with doramectin injectable solution on transmission prevention of Sarcoptes scabiei var. suis from sows to nursing piglets. Approximately 42 days prefarrowing, 58 mange-free sows were experimentally infested with 200 S. scabiei in each ear. Seven to fourteen days prior to farrowing, 22 sows were given doramectin injectable intramuscularly at a dose of 300 microg/kg of body weight. A total of 21 sows served as untreated controls. Skin scrapings for mite counts and lesion scoring were performed on sows before treatment on day 21, and on either day 35 or 42. Each sow was observed on days 0, 7, 14, 21, 28, and 35 or 42 for the incidence of scratching/rubbing. Skin scrapings, lesion scoring, and observation of scratching/rubbing were performed on the piglets after weaning and at the end of the nursery stage. Geometric mean mite counts of the untreated sows were 0.70 and 0.26 on days 21 and 35 or 42, respectively, and 0.00 for doramectin-treated sows over the same time periods (P<0.05). Lesions scores and the incidence of scratching/rubbing were both higher in the untreated sows as compared to the doramectin-treated sows during the same time periods (P<0.05). Geometric mean mite counts of piglets farrowed by untreated sows were 0.50 and 0.60 after weaning and at the end of the nursery stage, respectively, and 0.00 for piglets from doramectin-treated sows over the same time periods (P>0.05). Lesion scores and the incidence of scratching/rubbing were both higher in piglets from untreated sows as compared to those piglets from doramectin-treated sows (P<0.05). Treating S. scabiei-infested sows with doramectin injectable solution before farrowing eliminated mite infestation and prevented the transmission of S. scabiei to piglets.     

Effect of β‐carotene on health status and performance of sows and their litters

A total of 48 sows were allocated to four groups (12 sows per group) at the 99th day of pregnancy and were treated throughout two consecutive breeding cycles, as follows: (a) control group: no treatment; (b) group BC1: 400 mg β‐carotene/sow/day via feed from 7 days prior to the expected farrowing, until the 30th day postservice; (c) group BC2: 400 mg β‐carotene/sow/day via feed from 7 days before weaning up to service, followed by 200 mg β‐carotene until the 30th day postservice; and (d) group BC inj: four intramuscular (i.m.) injections of 200 mg β‐carotene/sow (on the 100th day of pregnancy, on the day of farrowing, on the day of weaning and on the first day of oestrus). Serum β‐carotene equivalents, vitamin A and IgG concentrations were determined in sows at several times of the breeding cycle. Moreover, serum IgG concentrations were determined in piglets on the second day of lactation and at weaning. Data relating to sow reproductive parameters and litter parameters were also recorded. It was shown that concentrations of serum β‐carotene equivalents were elevated only in the BC inj group during lactation and at service, while serum vitamin A concentrations were also elevated in the BC inj group only at oestrus. There was no effect of β‐carotene on the oestrus intensity score, the weaning‐to‐oestrus interval, the number of returns to oestrus per sow and the farrowing‐to‐farrowing interval. The number of piglets born alive was greater in the BC inj group compared with the controls, while the litter size at weaning was greater in the groups BC1, BC2 and BC inj compared with the control group (p < 0.05). Supplementation of β‐carotene did not appear to influence the serum IgG concentration in sows and piglets.     

Effects of breeding at the second oestrus or after post-weaning hormonal treatment with altrenogest on subsequent reproductive performance of primiparous sows

This study investigated the effects of breeding at the second oestrus after weaning or after feeding an orally active progestagen (altrenogest) on the subsequent reproductive performance of primiparous sows. After 3 weeks of lactation, 663 weaned sows of two genotypes were allocated into three groups: G1--breeding at the first oestrus after weaning; G2--breeding at the second oestrus after weaning and G3--treatment with altrenogest for 5 days after weaning and breeding at the first oestrus after the end of the treatment. Body weight at breeding was lower in G1 and G3 than in G2 sows (p < 0.05). The interval to show oestrus was similar for G1 and G2 groups (p > 0.05) but higher (p < 0.05) than that observed in G3 group. Within genotype A, percentages of females in oestrus within 10 days were not different (p > 0.05) among groups, whereas in genotype B, more G1 and G2 sows (p < 0.05) showed oestrus than G3 sows. In both genotypes, lower farrowing rates were observed in G3 than in G1 and G2 sows (p < 0.05) and a greater litter size (p < 0.05) was observed in G2 sows. In genotype A, the number of total born piglets was similar for G1 and G3 groups (p > 0.05), whereas in genotype B, G1 sows had a greater litter size than G3 sows (p < 0.05). Body weight at weaning and at breeding was similar (p > 0.05) between farrowed and non-farrowed sows in all groups. Reproductive performance is not improved in primiparous sows treated with altrenogest during 5 days after weaning. The reproductive performance of genotype B sows is compromised in Control and Altrenogest-treated sows but not in those bred at the second oestrus after mating. Breeding at the second oestrus after weaning allows primiparous sows to gain weight between weaning and service, and increases their farrowing rate and subsequent litter size.     

Some Factors Influencing the Losses of Pigs Prior to Weaning

Analyses of the records of 244 litters of purebred Yorkshire, Landrace, the crosses, backcrosses and crisscrosses of these two breeds were carried out to evaluate some of the factors influencing the losses of piglets prior to weaning.

There were differences in percentage survival between mating systems, with crossbred Landrace x Yorkshire piglets showing the highest rate of survival.

A direct relationship existed between the duration of farrowing and the incidence of stillbirths. The incidence of stillbirths was higher for male piglets than for female piglets.

Litter size at birth and weight loss of sow from parturition to weaning were important factors in determining litter size at weaning. Litter size at birth however, exerted a more important influence on litter performance than weight loss.

Age of sow had no significant effect on the number of piglets alive at weaning and implied that gilts were apparently as good mothers as sows.

From computed least squares estimates, it was implied that in general, piglets of low birthweights had much less chance of survival than those born with heavier weights.

     

Effects of sarcoptic mange on lactating swine and growing pigs

The impact of Sarcoptic mange on sows and on performance of their offspring from birth to slaughter was determined. Sows naturally infested with Sarcoptic mange were paired, mated to the same boar, and assigned randomly to treated or control farrowing groups. Treated sows received ivermectin s.c. at 300 micrograms/kg body weight; control sows received the vehicle s.c. Sow performance was evaluated via sow feed consumption, litter size, litter birth weights, litter weaning weights and piglet death loss from birth to weaning. Seven replicates (farrowing groups), each with six sow pairs, were included in the trial. Offspring from treated and control sows, 35 head/group, were fed to slaughter weights. Untreated sows had litters that weighed 4.14 kg less than ivermectin-treated sow litters at 21 d (P less than .07). Treated sows consumed 1.95 kg less feed per weaned piglet and .13 kg less feed per kilogram of weaned piglet (P less than .05). Piglets from treated sows were 5.79 kg/head heavier at slaughter (P less than .05) and had a .05 kg/d superior average daily gain (P less than .05).     

Maternal behaviour and performance in first-parity outdoor sows

When sows and their litters are kept outdoors, much of the responsibility for the litter is shifted from the herdsman to the sow compared to when the sows are kept indoors. Therefore, the maternal ability, including maternal behaviour, is believed to be important in outdoor piglet production. The aim of this study was to describe maternal traits in conventionally bred first-parity sows kept outdoors. Nursing behaviour, sow activity, sow body reserves, litter size and piglet growth were studied in 40 first-parity sows during a seven week long lactation. The sows were kept in groups outdoors. Sow activity (lying down or active) and nursing behaviour (nursing frequency, nursing duration and nursing terminator) were recorded on videotapes at four days post partum (pp) and directly observed at four and six weeks pp. Cross suckling was observed at four and six weeks pp. Sows were weighed and measured for backfat depth five days before farrowing, two weeks pp and at weaning seven weeks pp. Piglets were weighed at four days pp, at two weeks pp and at weaning. We concluded that sow nursing behaviour and activity are individual characteristics repeatable within sows' late lactation. Less active sows are more available for suckling. Light and thin sows have an earlier and more progressed weaning process than heavier, fatter sows. A significant positive relation was found between sow appetite in early lactation and piglet growth until weaning. Sow nursing behaviour is not important for piglet growth when sows and piglets are held in groups, piglets have access to sow feed and piglets are weaned as late as at seven weeks of age.     

Effects of salinomycin on sow weight change during lactation and on sow reproductive performance

Forty-five gravid cross-bred sows (mean parity 3.3 +/- .3) were randomly allotted to two dietary treatments: corn-soybean mean (CS) or CS plus 60 mg salinomycin per kilogram of diet (CSS). Sows were fed their respective diets through two successive parities with dietary treatment initiated at 100 d postcoitum and continued until weaning of the second successive litter. Therefore, sows fed CSS received salinomycin for 14 d before the first parturition and for approximately 153 d before the second parturition. Daily feed intake was restricted to 2 kg.hd-1.d-1 during gestation and to 3 kg.hd-1.d-1 from weaning to breeding. All sows. had ad libitum access to feed during lactation. Sows were weighed 7 d prior to parturition, at weaning and at breeding. Weaning-to-estrus interval and farrowing interval were recorded for all sows. Litters were weighed at birth and weaning. There were no differences (P greater than .05) between dietary treatments in sow weights before parturition, at weaning or at breeding for either first or second farrowing. The CSS-fed sows lost more weight from weaning to breeding after the first (P less than .03) and second (P less than .05) lactation periods than CS-fed sows. The CSS-fed sows tended to gain more (P = .06) weight during lactation than CS-fed sows. There were no differences (P greater than .05) between treatments in lactation feed intake, weaning-to-estrus interval, farrowing interval, litter size born or weaned, litter weights at birth or at weaning, or in sow culling rate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Preventing transmission of sarcoptic mange from sows to their offspring by injection of ivermectin. Effects on swine production

A blind and controlled field study was conducted on a pig farm in Australia to evaluate the activity of 1% ivermectin solution when injected into pregnant sows that were naturally infested with mites. The study was designed to appreciate the tolerance of the product on sows (litter size, litter birth weights, litter weaning weights, pre-weaning mortality) and to show the effects of sarcoptic mange on the growth performances of their offspring. Twenty sows were selected and ranked on Day-10, prior to the start of the study, on the basis of positive mite counts and parity. Sows were randomly allocated into two groups, A and B. On Day-7, they were injected once with product A (1 ml/33 kg; yielding 300 microg ivermectin/kg BW) or product B (placebo), respectively and then moved to the farrowing unit. Mite counts, ear and body lesions were scored and recorded. The average daily weight gain (ADG) was calculated on piglets from birth to Day-45 (ADG(45)) and birth to Day-70 (ADG(70)). Ivermectin was 100% efficient in preventing the transmission of scabies mites and did not have negative effect on the pregnant sows. Growth performances (ADG(45) and ADG(70)) of piglets from treated sows were significantly higher (452 and 541.5 g per day) than that from untreated sows (433.5 and 518.4 g per day) respectively, confirming that sarcoptic mange is detrimental to the production performances of growing pigs.     

Colostrum yield and litter performance in multiparous sows subjected to farrowing induction

The consumption of colostrum at a low level can compromise the survival and growth of piglets. Therefore, this study aimed to evaluate the effect of farrowing induction on colostrum yield, IgG concentration and the survival and performance of piglets until the weaning. Sows of parity 3 to 7 were assigned into two groups: Control (n = 48), sows with spontaneous farrowing; and induction (n = 48), sows induced to farrow on day 114 of gestation with a PGF₂ analogue. Colostrum and blood samples were collected from the sows, at farrowing and 24 hr later. Blood samples from the piglets were collected at 24 hr after birth. The performance of the piglets was evaluated in a subsample of 28 litters from each group. All piglets were weighed at 7, 14 and 20 days of age. The farrowing length, the number of piglets born alive, stillborn piglets, weight at birth, litter weight at birth and colostrum yield were not significantly affected (p > .05) by farrowing induction. There was no difference between the groups (p > .05) in the percentage of sows with obstetric interventions. Serum IgG concentration, in both sows and piglets, and colostrum IgG concentration were similar between the groups (p > .05). Furthermore, survival rate, piglet weight and litter weight at 7, 14 and 20 days of age were also similar between the groups (p > .05). Therefore, it can be concluded that the farrowing induction performed on day 114 of gestation does not affect the colostrum yield, the IgG concentration in colostrum and serum of piglets, and the litter performance until the weaning.     

Impact of rank position on fertility of sows

The investigations were carried out with 484 sows from two farms (farm A: housing the sows in small groups of 8 animals each, farm B with a large group of 100 sows) and a total number of 982 inseminations. The number of agonistic interactions was registered for each sow during 48 h after mixing soon after weaning the piglets at farm A. The individual rank place in the social hierarchy was calculated on the basis of wins and defeats and the sows were divided in high and low ranking sows. At farm B the rank position was estimated on the basis of the daily feeding order at two electronic feeding stations (first half of the sows in the feeding order = high ranking, second half = low ranking). Additionally, the following parameters were recorded for each sow: parity, genotype, farrowing rate and litter size (total and alive born piglets). The analysis showed that sows with a high rank position had a significantly higher farrowing rate (88.8%) compared to group-mates with low rank places (82.8%, p = 0.051) (farm A). Sows with a high rank position reached a significantly higher litter size of total born piglets (12.66, 16.14 piglets per litter respectively) than the low-ranking group-mates (12.13, 14.83 piglets/litter respectively — farms A and B). When mixing sows, the time and the conditions (e.g. group size, space allowance per sow) have to be considered to prevent the negative influence of low rank order on fertility.     

Socializing piglets before weaning: effects on behavior of lactating sows, pre- and postweaning behavior, and performance of piglets

This study evaluated how socializing piglets before weaning affects behavior of lactating sows and the pre- and postweaning behavior and performance of piglets. Two farrowing rooms, each with 6 pens, and 1 nursery with 4 pens were used. In total, data were obtained from 24 sows and their litters. In each farrowing room, the solid barriers between 3 farrowing pens were removed on d 12 after farrowing, and the sows remained confined in their crates (experimental group). In the other 3 farrowing pens of each farrowing room, sows and their litters were kept under conventional conditions until weaning (control group). All piglets were weaned 28 d after birth. After weaning, piglets from each group remained together in 1 pen of the nursery. The behavior of sows (lying, standing, sitting, nursing) and piglets (lying, active, suckling) in the farrowing rooms was observed for 24 h before and for 48 h after removal of the barriers between the pens. In addition, behavior (active, lying, feeding, agonistic behavior) of piglets was observed in the nursery during the initial 48-h period after weaning. Each piglet was weighed on d 5, 12, and 28 after birth and thereafter weekly until the fifth week of rearing. In the farrowing room, mixing of litters did not influence behavior of piglets and sows. Preweaning weight gain of the piglets did not differ (P = 0.60) between the treatments. In the initial 48 h after weaning, less agonistic behavior (P < 0.001) was observed in piglets belonging to the experimental group. During 5 wk of rearing, piglets in the experimental group gained more weight compared with the control group (P = 0.05). The advantage shown by the experimental group became especially conspicuous in the first week after weaning (P = 0.05). By socializing unfamiliar piglets before weaning, stress due to mixing could at least be distanced in time from the other burdens of weaning, thereby improving performance.     

Elimination of strains of Streptococcus suis serotype 2 from the tonsils of carrier sows by combined medication and vaccination

The effect of vaccination with a killed whole-cell vaccine of extracellular factor-positive Streptococcus suis serotype 2 (S suis 2 EF(+)) combined with medication with amoxicillin on the presence of virulent S suis 2 EF(+) strains on the tonsils of sows and their offspring was evaluated. In two herds, 14 pregnant sows that carried these virulent strains, as detected by PCR in three consecutive tonsillar brush samples, were selected and randomly assigned to be treated or left untreated as controls. The treated sows were vaccinated at six and three weeks before the expected farrowing date and medicated from one week before expected farrowing until the end of the experiment. Two weeks before parturition, the sows were housed in individual isolation farrowing rooms, and the sow and its litter were sampled by using tonsil brushes and tonsil swabs, respectively. Approximately 27 days postpartum, the sows and their piglets were euthanased and their tonsils were collected and analysed by pcr. No S suis 2 EF(+) could be detected in the tonsils of the seven treated sows, but the tonsils of the seven untreated sows remained positive. Only one of the litters of the untreated sows became infected, five days after birth, and none of the litters of the treated sows became infected.     

Influence of Postpartum Cloprostenol Treatment in Sows on Subsequent Reproductive Performance under Field Conditions

During the previous decade several studies focused on postpartum treatment with prostaglandin for improvement of reproductive performance in sows. The aim of the study was to investigate the effect of administration of a prostaglandin F_{2 α} (PGF_{2 α} ) analogue in sows within 24–48 h after farrowing on sow and litter performance. In five commercial farms, the sows were randomly assigned to either treatment A (2 ml cloprostenol, Planate^IM) or treatment B (2 ml physiological saline solution, i.m.). Fifteen per cent of all sows were at random selected for progesterone analysis. Litter performance was assessed by measuring pre-weaning mortality and average daily weight gain (ADG). Sow performance was assessed by measuring weaning-to-oestrus interval (WOI), the percentage of sows returning to oestrus and litter size during subsequent farrowing. Administration of a PGF_{2 α} analogue within 24–48 h postpartum had no effect on the rate of progesterone decline measured over 24 h compared with that of the controls. Litter performance and WOI were not affected by treatment. The subsequent litter size in sows of parity seven and more showed a significant difference of 1.98 piglets (p < 0.01) between both groups, to the benefit of the cloprostenol group. In conclusion, administration of a synthetic PGF_{2 α} analogue, cloprostenol, within 24–48 h after farrowing improved litter size at next farrowing in older (≥7 parity) sows.     

Stillbirth in the pig in relation to genetic merit for farrowing survival

The objectives of this study were to analyze the incidence of different categories of stillborn piglets in relation to genetic merit for farrowing survival of sows and litters and to analyze relationships of total number of piglets born per litter, average BW of the litter, and within-litter variation in BW with genetic merit for farrowing survival of sows and litters. Records of 336 purebred litters, produced by 307 first-to eighth-parity sows, were collected on a nucleus farm in Brouennes, France. Breeding values for farrowing survival were estimated for sows (EBVfs_maternal) and litters (EBVfs_direct) using a large data set from which information obtained in the current study was excluded. For each litter, BW, number of stillborn piglets (classified as nonfresh stillborn, prepartum stillborn, intrapartum stillborn, and postpartum stillborn), and number of live-born piglets were recorded. Birth weights of stillborn piglets were lower than BW of live-born piglets (P < 0.0001), except for prepartum stillbirths. The total number of stillborn piglets per litter and the number of stillborn piglets in each category decreased with increasing EBVfs_maternal (P < 0.01). An increase in EBVfs_direct was also associated with a decrease in the total number of stillborn piglets per litter (P < 0.01). This decrease was due to a decrease in the number of nonfresh, prepartum, and postpartum stillborn piglets but not to a decrease in the number of intrapartum stillborn piglets. Probabilities of stillbirth in relation to EBVfs_maternal were higher than probabilities of stillbirth in relation to EBVfs_direct. Total number of piglets born decreased with increasing EBVfs_direct (P = 0.0003), but was not related to EBVfs_maternal. Average BW of the litter (P < 0.0001) and within-litter variation in BW (P = 0.05) decreased with increasing EBVfs_maternal but were not related to EBVfs_direct. Selection for the maternal genetic component of farrowing survival seems a better strategy than selection for the direct genetic component. Selection for the maternal genetic component of farrowing survival reduces stillbirth in all categories and does not affect litter size.     

Folic acid and reproductive performances of sows

Two-hundred nine sows were used in a 2 X 2 split-plot unbalanced design to measure the effect of folic acid against control, and flushing against a normal level of feeding, between weaning and mating on the following variables: serum folates at weaning and at 60 d of gestation, blood hemoglobin (Hb) and hematocrit (Ht) after 15 wk of gestation and reproductive performance at farrowing. Folic acid was administered im according to a schedule that maintained serum folates at approximately the same level between weaning and 60 d of gestation. The treatments had no effect on Hb or Ht after 15 wk of gestation. Average live litter size was 12.0 piglets/litter for sows receiving the folic acid and flushing treatments as compared with 10.5 for sows without any treatment; the main effect of folic acid was significant (P less than or equal to .04). Intralitter variation in birth weight and total litter weight tended to be increased by folic acid administration. Results showed that the administration of folic acid during gestation could appreciably improve the reproductive performance of sows.     

Neonatal-piglet weight variation and its relation to pre-weaning mortality and weight gain on commercial farms

To determine the effect of within-litter neonatal-weight variation on pre-weaning mortality and weight gain, we analyzed piglet survival and weight gain within 400 litters from 10 commercial farms. Neonatal-weight variation (independent of mean neonatal weight, litter size and sow parity) was associated with pre-weaning survival and weaning-weight variation-but not with mean weaning weight. Neonatal piglets with weights well below the range of most of the litter (low-birth-weight piglets) had an increased risk of dying and were unable to obtain normal weight gains by weaning if they survived. These piglets experienced lower survival and poorer weight gain in larger litters. These piglets also tended to have lower survival but normal (albeit low) weaning weights if they survived in litters from middle-aged and old sows. High neonatal-weight variation resulted in lower survival and more variable weaning weights. Small piglets had a greater risk for poor survival and weight gain compared to their heavier litter-mates (a disadvantage that was exacerbated in large litters).     

Effect of feeding sorghum ergot (Claviceps africana) to sows during mid‐lactation on plasma prolactin and litter performance

Diets containing 3% sorghum ergot (16 mg alkaloids/kg, including 14 mg dihydroergosine/kg) were fed to 12 sows from 14 days post‐farrowing until weaning 14 days later, and their performance was compared with that of 10 control sows. Ergot‐fed sows displayed a smaller weight loss during lactation of 24 kg/head vs. 29 kg/head in control sows (p > 0.05) despite feed consumption being less (61 kg/head total feed intake vs. 73 kg/head by control sows; p < 0.05). Ergot‐fed sows had poorer weight gain of litters over the 14‐day period (16.6 kg/litter vs. 28.3 kg/litter for controls; p < 0.05) despite an increase in consumption of creep feed by the piglets from the ergot‐fed sows (1.9 kg/litter compared with 1.1 kg/litter by the control; p > 0.05). Sow plasma prolactin was reduced with ergot feeding after 7 days to 4.8 μg/l compared with 15.1 μg/l in the control sows (p < 0.01) and then at weaning was 4.9 μg/l compared with 8.0 μg/l (p < 0.01) in the control sows. Two sows fed ergot ceased lactation early, and the above sow feed intakes, body weight losses with litter weight gains and creep consumption indirectly indicate an ergot effect on milk production.