Control Sows Research Articles

Effects of alpha‐lipoic acid supplementation on antioxidative ability and performance of sows and nursing piglets

The current study was carried out to determine the effects of alpha-lipoic acid (LA) supplementation during late-gestation and lactation on antioxidative ability and performance of sows and their nursing piglets. A total of 160 multiparous sows were randomly allocated to four treatments with 40 replicates per treatment according to parity number and backfat (BF) thickness. Sows were fed 1 of 4 diets from day 85 of gestation to day 21 of lactation. Diets were control without LA; 400 ppm LA supplementation; 600 ppm LA supplementation; and 800 ppm LA supplementation. BF thickness of sows was determined on day 85 and 110 of gestation and days 1 and 21 of lactation. Piglet bodyweight was measured at birth, days 7, 14 and 21. Blood samples were obtained from the sows, and average daily feed intake (ADFI) of the sows during lactation was recorded. There were no differences in BF thickness or ADFI among treatment groups. Dietary LA supplementation resulted in a decrease in blood urea nitrogen (p < 0.01) concentration at days 110 of gestation. Dietary 800 ppm LA increased serum glutathione peroxidase (GSH-Px) activity (p < 0.05) and reduced maleic dialdehyde levels (p < 0.01) of sows compared with the control diet at days 21 of lactation. Alpha-lipoic acid supplementation increased the birthweight and weaning weight of piglets (p < 0.01) compared with the control group. Weight gains of piglets from sows fed the 800 ppm LA diets were greater (p < 0.01) between days 7 and 14 compared with piglets from control sows. Weight gains of piglets from sows fed the LA-supplemented diets were greater between days 14 and 21 (p < 0.05) and between days 1 and 21 (p < 0.01) compared with piglets from control-fed sows. In conclusion, the results indicate that antioxidant LA was effective in enhancing antioxidant enzymes activity and improving the performance of sows and their nursing piglets.

Dietary l-arginine supplementation enhances placental growth and reproductive performance in sows

Suboptimal embryonic/fetal survival and growth remains a significant problem in mammals. Using a swine model, we tested the hypothesis that dietary L-arginine supplementation during gestation may improve pregnancy outcomes through enhancing placental growth and modulating hormonal secretions. Gestating pigs (Yorkshire×Landrace, n=108) were assigned randomly into two groups based on parity and body weight, representing dietary supplementation with 1.0% L-arginine-HCl or 1.7% L-alanine (isonitrogenous control) between days 22 and 114 of gestation. Blood samples were obtained from the ear vein on days 22, 40, 70 and 90 of gestation. On days 40, 70 and 90 of gestation, concentrations of estradiol in plasma were higher (P<0.05) in arginine-supplemented than in control sows. Moreover, arginine supplementation increased (P<0.05) the concentrations of arginine, proline and ornithine in plasma, but concentrations of urea or progesterone in plasma did not differ between the two groups of sows. Compared with the control, arginine supplementation increased (P<0.05) the total number of piglets by 1.31 per litter, the number of live-born piglets by 1.10 per litter, the litter birth weight for all piglets by 1.36 kg, and the litter birth weight for live-born piglets by 1.70 kg. Furthermore, arginine supplementation enhanced (P<0.05) placental weight by 16.2%. The weaning-to-estrus interval of sows was not affected by arginine supplementation during gestation. These results indicate that dietary arginine supplementation beneficially enhances placental growth and the reproductive performance of sows.

Effects of altrenogest treatments before and after weaning on follicular development, farrowing rate, and litter size in sows1

In a previous study, we showed that follicle size at weaning affects the response of a sow to a short-term altrenogest treatment after weaning. In this study, an attempt was made to prevent the growth of follicles into larger size categories before weaning by using different altrenogest treatments before weaning to improve reproductive performance after postweaning altrenogest treatments. Sows (87 primiparous and 130 multiparous) were assigned to the following treatments: control (no altrenogest treatment; n=59), RU0-20 (20 mg of altrenogest from d -1 to 6; weaning=d 0; n=53), RU40-20 (40 mg of altrenogest from d -3 to 0 and 20 mg of altrenogest from d 1 to 6; n=53), and RU20-20 (20 mg of altrenogest from d -3 to 6; n=52). Follicle size was assessed daily with transabdominal ultrasound. Follicle sizes on d -3 (3.6 ± 0.7 mm) and at weaning (4.0 ± 0.7 mm) were similar for all treatments. Altrenogest-treated sows had larger follicles at the beginning of the follicular phase than did control sows [5.4 ± 0.1 and 3.8 ± 0.2 mm (least squares means), respectively; P < 0.0001] and on d 4 of the follicular phase [8.0 ± 0.1 and 6.7 ± 0.2 mm (least squares means), respectively; P < 0.0001]. Multiparous sows had larger follicles than did primiparous sows at the beginning of the follicular phase [5.3 ± 0.1 and 4.7 ± 0.1 mm (least squares means), respectively; P < 0.01] and on d 4 of the follicular phase [8.0 ± 0.1 and 7.0 ± 0.1 mm (least squares means), respectively; P < 0.0001]. Farrowing rate and litter size (born alive + dead) were not affected by treatment or parity. However, in primiparous sows, when mummies were included in litter size, altrenogest-treated sows had larger litters than did control sows (13.4 ± 0.5 and 11.9 ± 0.7 piglets, respectively; P=0.02). In primiparous control sows, backfat depth at weaning and litter size were positively related (slope of the regression line=0.82; P < 0.05), which was not the case in primiparous sows receiving altrenogest. In conclusion, the different altrenogest treatments before weaning did not prevent the growth of follicles before weaning and similarly affected subsequent follicle development and fertility. In primiparous sows, altrenogest treatment after weaning increased the number of fetuses during pregnancy, but positive effects seemed limited by uterine capacity. Altrenogest treatment after weaning improved litter size in primiparous sows with reduced backfat depth at weaning, which suggests a specific positive effect of a recovery period after weaning in sows with reduced BCS at weaning.

Patterns of Corpora Lutea Growth and Progesterone Secretion in Sows with Thrifty Genotype and Leptin Resistance due to Leptin Receptor Gene Polymorphisms (Iberian Pig)

The current study aimed to compare luteal function, as measured by corpora lutea dynamics and progesterone secretion, in 10 sows with obesity/leptin resistance genotype (Iberian pig) and 10 females of lean commercial crosses (Large White × Landrace). In all the animals, the oestrous cycle was synchronized with progestagens, and ovulation was induced by exogenous gonadotrophins. Thereafter, number and size of follicles and plasma oestradiol concentration were determined at oestrus detection, and number and size of corpora lutea and progesterone concentration were evaluated from Day 4 to 12 of the cycle. There were no differences between genotypes in follicle population and oestradiol concentration, and ovulation rate (15.2±1.3 in Iberian vs 12.7±1.8 in LWxL sows); however, there was a higher percentage of Iberian than control sows showing luteal cysts (66.7% vs 30%, respectively; p<0.05). In both breeds, both total luteal area and plasma progesterone concentration grew linearly from Day 4 to 8 (p<0.01) and remained more stable between Days 8 and 12, without significant differences between genotypes. In conclusion, current study supports that ovulatory processes and luteal functionality are not the main limiting factors for prolificacy in a pig model of leptin resistance and obesity.

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.

Effect of dietary CLA administration on fatty acid composition and lipogenic and lipolytic enzyme activities in suckling and weaned piglets

The objective of this study was to determine the effects of conjugated linoleic acid (CLA) administration during the lactation and post-weaning period or in the post-weaning period exclusively on fatty acid (FA) composition and enzymatic regulation in suckling and in 63-d-old piglets. During the nursery phase, 18 piglets individually penned were used and three dietary treatments ( n = 6) were applied: (1) piglets that proceeded from control sows fed a control diet (0 g CLA/kg) (CT-CT), (2) piglets from control sows fed a diet containing 10 g CLA/kg (CT-CLA) and (3) piglets from CLA fed sows fed diets containing 10 g CLA/kg (CLA-CLA). Suckling piglets (28 d of age) from sows fed the CLA enriched diet showed higher concentration of saturated FA (SFA), lower concentration of total monounsaturated FA (MUFA) and lower MUFA/SFA, C16:1 n-7/C16:0 and C18:1 n-9/C18:0 ratios in subcutaneous backfat than those from sows fed the control diet ( P<0.05). No CLA isomers were detected at weaning in the subcutaneous backfat of piglets from sows fed the control diet, but 0.44 g/100 g total FA (TFA) c9, t11-CLA and 0.12 g/100 g TFA t10, c12-CLA were observed in piglets from CLA fed sows. Also, increased c9, t11-CLA, t10, c12-CLA and SFA proportions ( P<0.05) and decreased MUFA and MUFA/SFA and C16:1 n-7/C16:0 ratios were found in the liver of piglets from CLA fed sows ( P<0.05). In 63-d-old piglets, malic enzyme activity in subcutaneous fat was lower in groups in which CLA was fed to sows and piglets or only to piglets than in the group that did not receive any CLA supplementation ( P<0.05). No effect of dietary CLA on heart L-3-hydroxyacyl-CoA dehydrogenase and glucose-6-phosphate dehydrogenase and malic enzyme activity in liver was observed. The concentration of c9, t11-CLA and t10, c12-CLA at weaning was negligible in piglets from sows fed the control diet, but after being fed for 35 d the diet enriched with CLA, the concentration was similar to that of piglets fed milk and diet containing CLA. Little alteration of enzyme regulation induced by CLA feeding was found in piglets either at 28 or 63 d of age, except for malic enzyme activity, which was lower in 63-d-old piglets fed the CLA enriched diet after weaning.

Effects of tryptophan supplementation on aggression among group-housed gestating sows1

The objective of this study was to determine the effects of dietary Trp supplementation on mixing-induced aggression and the associated stress, and on reproductive performance in gestating sows. After weaning, sows were mixed in pens with electronic sow feeders on concrete-slatted floors. Each pen housed 21 ± 2.8 sows, with approximately 2.7 ± 0.43 m(2)/sow of floor space allowance. Multiparous sows (n = 168) from 8 breeding groups were used, with 4 groups assigned to a control diet and 4 groups assigned to a high-Trp diet. Control sows received corn- and soybean meal-based diets throughout gestation (0.15% Trp) and lactation (0.21% Trp). Three days before and after mixing, sows assigned to the high-Trp treatment received approximately 2.3 times the dietary Trp (0.35% in the gestation diet and 0.48% in the lactation diet) fed to control sows. Six focal sows (2 sows from each of parity 1, 2, and 3 or greater) in each pen were designated and videotaped for 72 h after mixing to determine the type and number of aggressive interactions among sows. Before and 48 h after mixing, saliva samples were collected from focal sows, and scratches were assessed on all sows. Data were analyzed using the FREQ and GLIMMIX procedures (SAS Inst. Inc., Cary, NC). Aggression among sows was intense during the initial 6 h and decreased between 6 and 72 h after mixing. The initial aggression caused scratches and increased cortisol concentrations (P < 0.05). Mature sows tended to fight for longer periods (112 vs. 52 s/h per sow, SE = 23.8; P < 0.10) but had fewer scratches caused by aggression (injury score = 4.3 vs. 6.5, SE = 1.13; P < 0.01) than parity-1 sows. Supplementation of dietary Trp reduced the total duration of head-to-head knocking (P < 0.05) but did not affect other aggressive behaviors. There was no difference between dietary treatments in injury scores or saliva cortisol concentrations. Sows in the high-Trp treatment had more total piglets born (12.5 vs. 10.5 pigs/litter, SE = 0.55; P < 0.05) and more stillborn piglets (1.5 vs. 0.8 pigs/litter, SE = 0.20; P < 0.05), but had no significant change (P = 0.12) in piglets born alive (10.8 vs. 9.7 pigs/litter, SE = 0.42) compared with control sows. The results indicate that the initial aggression after mixing caused more injuries in young sows than in mature sows. Supplementation of dietary Trp at 2.3 times the control amount for a short period did not effectively reduce aggression and the associated stress in sows at mixing.

208 IN VITRO FERTILIZATION UNDER SIMULATED STRESS AND SUBSEQUENT IN VITRO EMBRYO PRODUCTION IN THE PIG

Fertilization is a crucial step for successful reproduction and can be negatively influenced by stressful situations. It is generally accepted that stress affects reproduction, altering the endocrine profile of the female. An altered hormonal environment where the oocyte is developing could affect critical processes such as fertilization. Using a mixed in vivo–in vitro system, we assessed the ability of the oocyte to undergo fertilization and early development after exposure to blood plasma from sows that had experienced simulated stress through repeated injections of adrenocorticotropic hormone (ACTH) before ovulation (known concentrations of cortisol and reproductive hormones as well as exact ovulation time assessed by ultrasonography). Oocytes (n = 926, 7 replicates) collected from abattoir ovaries were matured in TCM-199 with BSA supplemented with hormones (10 IE mL–1 of pregnant mare serum gonadotropin and 5 IE mL–1 of hCG) and insulin-transferrin-selenium (5 μL mL–1) for 24 h, followed by 22 h without supplements. During IVF, gametes were exposed to 10% of pooled plasma (n = 3 per treatment) collected approximately 1 h before ovulation from ACTH-treated sows (A group), nontreated control sows (C group), or media with BSA (B group) for 24 h. Fresh semen was added at 5 × 105 cells mL–1. Afterward, the remaining cumulus cells and sperm were removed from oocytes by vortexing (1 min), and presumptive zygotes were placed in culture medium (porcine zygote medium). Cleavage rate was assessed at 48 h post-insemination (hpi) and the embryos (n = 433, 7 replicates) were cultured up to Day 7 and stained with Hoechst 33342 (10 μg mL–1) to count the total number of nuclei. In addition, non-cleaved oocytes were stained at 48 hpi with Hoechst to assess sperm-zona binding. Binding to the zona was assessed only in oocytes found to be matured. Statistical analysis was done using Kruskal-Wallis ANOVA and the Mann-Whitney U test. The number of spermatozoa bound to the zona pellucida was higher in the B group, and binding was notably negatively affected in the ACTH group (0.43 ± 0.18, 35.93 ± 2.50, and 3.44 ± 1.04 for the A, B, and C group, respectively; P &lt; 0.001). Cleavage rate (over total number of presumptive zygotes) in the A group (30.71 ± 3.76%) was significantly lower than in the control groups (59.93 ± 4.0 and 52.2 ± 5.31% for the B and C group, respectively; P &lt; 0.01). Blastocyst rate expressed over the total number of embryos was reduced in the A group (9.40 ± 5.20%) compared with the controls (27.10 ± 5.79 and 25.66 ± 5.28% in the B and C group, respectively; P &lt; 0.05). However, no differences were found in the total number of nuclei in the blastocysts. The results suggest that fertilization is a sensitive event that could be negatively influenced by stress, subsequently affecting early embryo development. A reduced number of spermatozoa attached to the zona and a lower number of embryos and lower blastocyst development were observed in the simulated-stress group. Further studies would help to elucidate which (in the oocyte, spermatozoon, or both) mechanisms are being affected by ACTH-simulated stress around fertilization. Data are expressed as mean ± SEM. Funded by Formas.

Response of pregnant and lactating sows to reduced protein content in complete compound feed

The experimental material consisted of 42 sows divided into 3 feeding groups, each containing 14 sows fed complete compound feed varying in protein content. Protein and amino acid content of the feed fed to the control group was in compliance with Polish standards. Protein content in the experimental groups was reduced by 10% and 20%, respectively. At the same time, lysine, methionine, threonine and tryptophane content was supplemented to the level of the control group. All pregnant and lactating sows were fed individually. The condition of the sows was determined by measuring the thickness of backfat at the P2 position on days 30 and 105 of pregnancy and on day 25 of lactation. The data analyzed in the study included: the total number of piglets born, their body weight gain, milk composition, weaning-to-estrus interval and the farrowing rate. Protein content of the compound feed did not have a significant impact on the increment in backfat during pregnancy and losses during lactation. The sows fed compound feed with reduced protein content gave birth to 0.7 and 0.6 less piglets per litter than the control animals. However, due to lower losses, they bred 0.3 and 0.4 more piglets than the control sows. Average body weight of a piglet on day 21 was 0.5 kg lower in the experimental than in the control group. Dry matter, protein, fat and lactose content of the sow's milk did not depend on protein content of the feed. The weaning-to-estrus interval in the experimental groups was one day longer than in the control group. The reproductive rate accounted for 86% and was comparable in all the groups.

Linseed meal during early pregnancy increases litter size in pigs without affecting post-natal growth

To determine how feeding linseed meal (LSM) during gestation influences litter size, placental weight, and piglet growth, sows (n = 30) received a phytoestrogen-free Control diet throughout gestation; 12.5% LSM diet throughout gestation (LSM114); or 12.5% LSM diet from day 1 to day 15 of gestation and control diet until parturition (LSM15). Maternal diet did not affect birth weight, placental weight, or postnatal growth. The number of fully formed piglets was increased (P = 0.05) in LSM15 sows compared with Control and LSM114 sows (13.5 vs. 10.1 and 11.6 ± 1.0, respectively). Feeding LSM during the first 2 wk after breeding may enhance litter size.

Fertility of Sows Fed ad libitum with a High Fibre Diet During Pregnancy

The effect of ad libitum (ADLIB) feeding strategy on the fertility of the group housed sow was studied in a prospective field trial during 1.5 years. All study animals farrowed under standard farrowing circumstances in crates, and they were provided with an ad libitum feeding throughout the 30-day lactation. After weaning, animals were randomly allocated to one of the two dry sow feeding strategies (AD LIB or CONT). After oestrus detection in groups, they were artificially inseminated and moved into pregnancy pens with partially slatted floor, in groups of 40 sows each. The ADLIB sows (n = 447) were loose housed and provided with ad libitum access to 7.7 MJ/kg feed high in fibre from two feeders per group. The control sows (n = 479; CONT) were also loose housed and given a standard dry sow feed in feeding stalls once a day (2.5 kg/day. The energy content of the feed was 9.3 MJ/kg NE). The feeding strategy (ADLIB vs CONT) had no effect on pregnancy rate (85.8 vs 90.9, p > 0.05), weaning to oestrus interval (7.7 vs 7.3 days, p > 0.05), piglets born alive (11.5 ± 3.5 vs 11.6 ± 3.3, p > 0.05), stillborn piglets (1.2 ± 1.8 vs 0.9 ± 1.5, p > 0.05) nor on progesterone concentration (p > 0.05). CONT sows weaned more piglets (9.7 ± 2.2 vs 9.4 ± 2.0, p < 0.01), whereas the piglets of AD LIB sows were heavier at weaning (8.8 ± 0.9 vs 8.0 ± 1.3 kg, p < 0.05). In conclusion, ad libitum feeding with a high in fibre diet during pregnancy did not affect the reproductive performance.

Relationships among gilt and sow live weight, P2 backfat depth, and culling rates

To examine a high culling rate problem, data were collected on 2154 sows culled from a commercial 5400-sow farrow-to-finish unit in New South Wales, Australia, during a 12-month period. Data recorded were parity, body weight, P2 backfat depth, and reason for culling. Additionally, body weights and backfat depths were recorded for a cross-section of the herd (3378 sows) in order to provide control sows for comparison. Reasons for culling were 63.7% for reproductive inefficiency or failure, while a further 12% were due to locomotor problems. Of females culled for reproductive reasons, 42.2% were gilts, indicating gilt management to be a major contributor to the high culling rate. When adjusted for parity, season, and day relative to weaning, culls had lower body weights (P &lt; .05) and less backfat depth (P &lt; .001) than controls (209.7 versus 211.4 kg and 14.8 versus 15.3 mm for culls and controls, respectively). These data suggest that inadequate sow nutrition was a contributor to the high culling rates, although the main problem was gilt management. Studies are ongoing to determine effects on retention of increased backfat and body mass of gilts at breeding and of providing increased dietary protein to younger sows.

Relationships between ovarian cysts and morphological and hormonal state of ovarian cortex in sows

The aim of this study was to evaluate the relationship between ovarian cysts and concentrations of ovarian steroid hormones: 17β-estradiol (E 2), progesterone (P 4), testosterone (T), and androstendione (A 4) both in blood plasma and in cysts and morphological state of the ovarian cortex in sows. Females were divided into three groups: PCO (sows with polycystical ovaries), OO (sows with oligocystic ovaries) and control (sows without ovarian cysts). The ovaries for evaluations were collected after slaughtering of 18 multiparous sows. Between the PCO and OO animals, statistically significant differences in numbers of the follicular cysts (FC) (8.6 vs. 1.5), follicular theca-lutein cysts (FTLC) (8.0 vs. 2.0), follicular lutein cysts (FLC) (4.5 vs. 2.0) and corpus luteum cysts (CLC) (1.7 vs. 0.4) ( P ≤ 0.01) were noted. In the PCO sows the most common kinds of cysts were FC and FTLC (8.6 and 8.0) whilst in OO sows the cysts occurred on their ovaries on a similar level (FC – 1.6, FTLC – 2.0, FLC – 2.0). Existence of more than 10 ovarian cysts in the sows significantly decreases the frequency of physiological ovarian follicles (primary, growing and maturing) and significantly increases the pathological process of atresia on all stages of ovarian follicles development ( P ≤ 0.01). The study did not reveal any effect of growing or decreasing number of ovarian cyst on concentrations of E 2 and P 4 in blood plasma of sows. Polycystical ovaries significantly decreased concentrations of A 4 but increased the concentration of T in blood plasma ( P ≤ 0.01). The general presence of ovarian cysts considerably positively correlated with concentrations of E 2, T and A 4 from cysts’ fluid, of all kinds of ovarian cysts and atresia of primary follicles (a correlation coefficient r from 0.72 up to 0.97, P ≤ 0.05). The phenomenon of ovarian cysts significantly negatively correlated with all generations of ovarian follicles ( P ≤ 0.05).

Effects of deoxynivalenol (DON) in the lactation diet on the feed intake and fertility of sows

A diet contaminated with 2.8mg deoxynivalenol (DON)/kg was fed at 6kg per day to 32 mycotoxin-exposed pluriparous sows (M) during lactation. The 31 control sows (C) received 6kg of an uncontaminated diet. Although more contaminated diet was refused (P = 0.05), DON exposure had no effect (P > 0.1) on body weight loss of the sows during lactation (M: 27.9 ± 12.3kg; C: 29.7 ± 10.2kg), the number of weaned piglets (M: 9.8 ± 1.4; C: 9.7 ± 1.6) and their daily weight gain (M: 266 ± 70g; C: 272 ± 64g). Several sows were culled after weaning for reasons unrelated to the experiment. Compared with the remaining 21 C sows, the remaining 26 M sows had an identical interval between weaning and the next farrowing (M: 120 ± 1days; C: 120 ± 1days) and a similar litter size (M: 14.5 ± 2.7; C: 14.9 ± 3.0; P > 0.10). The daily intake of 17mg DON during lactation thus did not affect the reproductive performance of the sows.

Feed transition between gestation and lactation is exhibited earlier in sows fed a high-fiber diet during gestation1

The underconsumption of feed frequently observed in young sows during lactation can result from an adaptation problem of the sow to the new feeding management in terms of diet composition and feeding amount. Our study aimed to investigate how the sow manages her own feed transition when given the choice between the gestation diet and the lactation diet from moving into the farrowing crate (12 d before farrowing) until the second week postpartum. The effect of adding dietary fiber to the gestation diet on this transition was also evaluated. During gestation, 16 primiparous sows (Large White x Landrace) were fed 2.4 kg/d of a control (CON) diet (3.5% of crude fiber), or 2.9 kg/d of a high-fiber (HF) diet (12.8% of crude fiber). The daily allowance of NE was 24 MJ in both treatments. Twelve days before the expected parturition day (d -12), sows were moved into farrowing crates that were equipped with a computerized feeding device allowing the gestation and lactation diets to be supplied via 2 rewarded push buttons placed above the trough, until d 14 postpartum. The feeding transition was evaluated through the daily ratio of ingestion of the lactation diet. Feeding behavior was measured through daily feed and energy intakes, number of daily meals, meal size, and the nycthemeral distribution of feeding activity. Sows were weighed and backfat thickness was measured at the beginning and end of gestation and lactation. Piglets were weighed every week from birth until weaning. The transition to the lactation diet occurred earlier in HF sows (P < 0.05); the 50% threshold of lactation diet ingestion was reached on d -8 and 12 in HF and CON sows, respectively. Dietary treatment did not affect the feeding pattern, and all sows presented a diurnal feeding activity. During lactation, there was an interaction (P < 0.05) between the hour of the day and the dietary treatment for the distribution of pushes on the rewarded buttons, with pushes being more spread out throughout the day in CON sows compared with HF sows. Variations in sow backfat thickness were not affected by dietary treatment, but HF sows lost more BW during lactation (P < 0.05). Growth of piglets was not affected by dietary treatment. In conclusion, sows chose the lactation diet spontaneously on the week preceding parturition when they were fed a fibrous diet during gestation. This highlights the possible impact of such a gestation diet to promote early intake of the lactation diet.

Effect of gonadotropin treatment on estrus, ovulation, and litter size in weaned and anestrous sows1

In the first of 2 experiments, we evaluated the effects on anestrous sows of pretreatment with FSH to stimulate the growth of small follicles, followed by eCG to stimulate the growth of medium follicles, estrus, and ovulation. In Exp. 2, we examined the effect of sows receiving 400 IU of eCG plus 200 IU of hCG (PG 600, Intervet/Schering Plough Animal Health, Boxmeer, the Netherlands) at weaning and then different doses and timing of supplemental hCG. In Exp. 1, a total of 87 multiparous Hypor sows deemed anestrus 7 d after weaning were assigned to intramuscular (i.m.) injection of 1) PG 600, 2) eCG (600 IU), 3) pretreatment with 87.5 IU of FSH on d 7 and 8 plus eCG on d 9, or were 4) noninjected controls. Sows had daily boar contact for 15 d after weaning for estrus detection. Blood samples were obtained on d 9 and 19 and assayed for progesterone to determine ovulation status. The weaning-to-estrus interval, number of sows in estrus and ovulating, farrowing rate, and litter size were not different (P > 0.1) in treated groups compared with controls. In Exp. 2, a total of 247 Hypor sows were assigned at weaning by parity (1 and 2 or > or = 3) to receive 1) an i.m. injection of PG 600, 2) PG 600 supplemented with 100 IU of hCG injected either concurrently or after 24 h, 3) 200 IU of hCG after 24 h, or 4) no injection (controls). Sows were exposed to boars daily for 7 d. After treatment of parity 1 and 2 sows, all gonadotropin-treated groups had an increased (P < 0.05) number of sows in estrus compared with the control group; weaning-to-estrus interval, farrowing rates, and litter size were unaffected (P > 0.1). After treatment of parity > or = 3 sows, there was no treatment effect on the estrous response and weaning-to-estrus interval; compared with control and PG 600-treated sows, farrowing rate was decreased (P < 0.05) for sows receiving 200 IU of hCG after 24 h. There was no effect (P > 0.1) of treatment on litter size. We conclude that gonadotropins can be used to increase estrus response in weaned sows, but that hCG treatment subsequent to PG 600 may be detrimental to sow fertility in parity > or = 3 sows.

Post-weaning Altrenogest treatment in primiparous sows; the effect of duration and dosage on follicular development and consequences for early pregnancy

Our objective was to investigate follicle development in sows during and after different Altrenogest treatments post-weaning and relate this to subsequent ovulation rate and embryonic development. Primiparous UPB sows ( n = 47) were randomly assigned to (weaning = Day 0): control (no Altrenogest, n = 12), RU8-15 (15 mg of Altrenogest, Day-1 till Day 7, n = 12), RU8-20 (20 mg of Altrenogest, Day-1 till Day 7, n = 12) or RU15-15 (15 mg of Altrenogest, Day-1 till Day 14, n = 11). From weaning onwards, trans-abdominal ultrasound was performed daily. Sows were slaughtered on Day 4 or 5 after ovulation. Follicle size increased during Altrenogest treatment and reached a plateau around Day 6, regardless of dose (4.6 ± 1.5, 4.6 ± 1.6 and 4.6 ± 1.6 mm for RU8-15, RU8-20 and RU15-15, respectively). This increase resulted in larger follicles ( P = 0.0002) at the onset of the follicular phase (i.e. time of weaning for control sows and 24 h after last administration of Altrenogest for treated sows); 4.8 ± 1.8, 4.8 ± 1.4, 4.9 ± 0.9 mm and 2.9 ± 0.8, for RU8-15, RU8-20, RU15-15 and controls, respectively. Pre-ovulatory follicle size tended ( P = 0.07) to be larger for treated animals (7.9 ± 2.4, 7.9 ± 0.7, 8.6 ± 1.3 and 6.9 ± 0.9 mm for RU8-15, RU8-20, RU15-15 and controls, respectively). The interval follicular phase-oestrus was shorter ( P = 0.005) for treated animals. Treatment did not affect ovulation rate or early embryonic development. However, for treated animals, the increase in follicle size during treatment was positively related with ovulation rate ( P = 0.05). In conclusion, post-weaning treatment with Altrenogest of first litter sows influenced follicle size and shortened the follicular phase, but did not affect ovulation rate or early embryonic development.

Colostral transmission of porcine circovirus 2 (PCV-2): reproduction of post-weaning multisystemic wasting syndrome in pigs fed milk from PCV-2-infected sows with post-natal porcine parvovirus infection or immunostimulation

Post-weaning multisystemic wasting syndrome (PMWS) was reproduced in pigs fed colostrum and milk from porcine circovirus 2 (PCV-2)-infected sows and infected post-natally with porcine parvovirus (PPV) or immunostimulated. Pregnant sows were inoculated intranasally with either PCV-2 (n=5) or PCV-2-free PK-15 cell lysates (control, n=10) 3 weeks before the expected farrowing date. Newborn piglets from five of the control sows were introduced to PCV-2-infected sows (n=6 for each sow) and allowed to feed on the colostrum for 12 h and then given 15 ml milk five times a day for 7 days. Newborn piglets from the other five control sows were fed colostrum and milk from their own sows. After 7 days, two piglets from each group were randomly selected to confirm PCV-2 infection. Twenty-one pigs fed by PCV-2-infected sows were randomly divided into three groups and subjected to post-natal PPV infection (group 1), immunostimulation (group 2) or no post-natal treatment (group 3). Twenty-one pigs fed by uninfected sows were also randomly divided and subjected to post-natal PCV-2 and PPV infection (group 4), post-natal PCV-2 infection (group 5) or no treatment (group 6, negative control). Body weight was significantly greater in group 6 than in groups 1, 2 and 4 at 49, 52, 56, 59 and 63 days of age. The typical granulomatous inflammatory reaction and lymphoid depletion of PMWS was observed in the lymph nodes of groups 1, 2 and 4 at 63 days of age. Group 3 had significantly fewer PCV-2-positive cells than groups 1, 2 and 4. In conclusion, PCV-2 shed from colostrum and milk is infectious and reproduces PMWS with post-natal PPV infection or immune stimulation.

Effects of maternal plasmid GHRH treatment on offspring growth

To differentiate prenatal effects of plasmid growth hormone-releasing hormone (GHRH) treatment from maternal effects mediated by lactation on long-term growth of offspring, a cross-fostering study was designed. Pregnant sows ( n = 12) were untreated ( n = 6) or received either a Wt-GHRH ( n = 2) or HV-GHRH ( n = 4) plasmid. At birth, half of each litter was cross-fostered (treated to controls and controls to treated only). Piglets from plasmid-injected sows were heavier at birth (HV-GHRH, 1.65 ± 0.07 kg; Wt-GHRH, 1.46 ± 0.05 kg vs. Controls, 1.27 ± 0.03 kg; P ≥ 0.001) and at weaning (Wt-GHRH, 6.01 ± 0.21 kg and HV-GHRH, 6.34 ± 0.15 kg vs. Controls, 5.37 ± 0.14 kg; P ≥ 0.02, respectively). Control piglets cross-fostered to plasmid-injected sows grew faster to weaning (Wt-GHRH, 5.61 ± 0.15 kg and HV-GHRH, 5.70 ± 0.29 kg vs. Controls, 5.08 ± 0.22 kg; P > 0.05, respectively). Piglets from plasmid-injected sows that suckled on control sows were larger than control piglets on control sows (Wt-GHRH, 5.93 ± 0.20 kg and HV-GHRH, 6.2 ± 0.19 kg vs. Controls, 5.08 ± 0.22 kg; P > 0.05, respectively), but smaller than their littermates left on their treated mothers. The observed improvements were maintained until the end of the study when the offspring were 170-day-old. The results suggest that the improved growth of offspring of GHRH plasmid-treated sows pre-weaning is attributable to improved maternal performance, while after weaning the effects on the pituitary component are relevant.

Altrenogest treatment during late pregnancy did not reduce colostrum yield in primiparous sows1

The decrease in circulating concentrations of progesterone is the lactogenic trigger in many species. The aim of the present study was to determine the effect of an orally active progestogen, altrenogest, administered in late gestation, on lactogenesis in sows. Gilts were treated with altrenogest (20 mg/d) from d 109 to 112 of gestation (ALT112, n = 6) or d 113 (ALT113, n = 8) or were not treated (control, n = 9). Colostrum production, estimated from the BW gains of the piglets, was measured during 24 h starting at the onset of parturition. Colostrum samples were collected at the onset of parturition until 48 h later. Jugular blood samples were taken from d -8 prepartum until d 3 postpartum. Altrenogest treatment extended the gestation length of ALT113 sows in comparison with control sows (116.3 vs. 114.7 d; P < 0.05). Litter size and litter weight at birth did not differ between groups (P > 0.1). Estimated colostrum yield was not reduced in altrenogest-treated sows compared with control sows (4.20 kg) and tended to be greater in ALT112 (4.73 kg) than in ALT113 sows (3.74 kg; P = 0.09). Altrenogest reduced endogenous progesterone concentrations during the 2 d prepartum in ALT113 relative to control sows (P < 0.05), likely because luteolysis occurred earlier in relation to parturition in ALT113 sows. Altrenogest reduced estradiol-17beta concentrations during the 2 d prepartum in ALT113 (P < 0.05) and ALT112 (P < 0.1) sows. Altrenogest treatment did not influence the timing of the prepartum peak of prolactin in relation to parturition. The ALT113 sows had lesser (P < 0.05) concentrations of lactose in plasma and a lesser Na:K ratio in colostrum after parturition than Control and ALT112 sows, indicating that the junctions between their mammary epithelial cells were tighter. Concentrations of colostral IgG in sows that received altrenogest tended to be less than in control sows (P = 0.08). In conclusion, altrenogest administered from d 109 to 112 or 113 of pregnancy did not affect lactogenesis in sows, possibly because the treatment delayed farrowing and main hormonal changes without affecting the relative chronology of these changes.