Maternal backfat depth in gestating sows has a greater influence on offspring growth and carcass lean yield than maternal feed allocation during gestation

A commercial pig spends nearly half of its life in utero and its nutrition during this time can influence birth weight and postnatal growth. We hypothesised that postnatal growth is increased in pigs raised by sows with a high backfat depth and high level of energy intake during gestation compared with sows with a low backfat depth and low level of energy intake during gestation. This was tested in a 2×3 factorial design experiment with 2 factors for gilt backfat depth (Thin and Fat) and 3 factors for gestation feed allowance (Restricted, Control and High). Between d 25 and d 90 of gestation, Thin gilts (n=68; 12±0.6 mm P2 backfat) and Fat gilts (n=72; 19±0.6 mm P2 backfat) were randomly allocated, as individuals, to a gestation diet (6.19 g/kg lysine, 13.0 MJ DE/kg) at the following feed allowances: 1.8 kg/day (Restricted); 2.5 kg/day (Control) and 3.5 kg/day (High). For the remainder of gestation and during lactation all gilts were treated similarly. At weaning (day 28), 155 piglets were sacrificed and 272 were individually housed and followed through to slaughter (day 158). At day 80 of gestation, fasted Thin Restricted gilts had lower serum IGF-1 concentrations than Thin High or Thin Control fed gilts (P<0.001). Pigs born from Fat gilts had greater backfat depths (P<0.05), a lower lean meat yield (P<0.05) and were heavier (P<0.05) at slaughter than pigs born from Thin gilts. Gilt gestation feed allowance had only transitory effects on average daily gain and feed conversion efficiency and had no effect on pig weight at slaughter (P>0.05) or lean meat yield (P>0.05). In conclusion, gilts with a backfat depth of ~19 mm at insemination produced pigs that were heavier and fatter at ~158 days of age than those born from gilts with ~12 mm backfat depth at insemination. Maternal body condition during gestation had a more predominant influence on growth parameters of the offspring, such as weight at slaughter and backfat depth, than did feed level during gestation.     

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

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

Supplemental progesterone during early pregnancy exerts divergent responses on embryonic characteristics in sows and gilts

Progesterone (P4) plays a key role in pregnancy establishment and maintenance; during early pregnancy, P4 stimulates the production and release of uterine secretions necessary for conceptus growth prior to implantation; therefore, exogenous P4 supplementation may improve embryo development. This study evaluated the effects of supplementation during early pregnancy with long-acting injectable progesterone or altrenogest on embryonic characteristics of sows and gilts. Thus, a total of 32 sows and 16 gilts were used. On day 6 of pregnancy sows and gilts were allocated to one of the following groups: non-supplemented; supplemented with 20 mg of altrenogest, orally, from days 6 to 12 of pregnancy; supplemented with 2.15 mg/kg of long-acting injectable progesterone on day 6 of pregnancy. Animals were killed on day 28 of pregnancy, and ovulation rate, embryo survival, embryo weight, crown-to-rump length, uterine glandular epithelium and endometrial vascularization were assessed. Treatments had no effect on pregnancy rate, embryo survival or endometrial vascular density (P > 0.05). Non-supplemented gilts presented larger and heavier embryos compared to gilts from supplemented groups (P < 0.05). Sows in the altrenogest group presented larger and heavier embryos compared to non-supplemented sows and sows supplemented with long-acting injectable progesterone. In conclusion, supplementation of sows and gilts with progestagen from day 6 of pregnancy can be used as a means to improve embryo survival without deleterious effects.     

Age at puberty, ovulation rate, uterine length, prenatal survival and litter size in Chinese Meishan and Yorkshire females

Studies on the ovulation rate, prenatal survival and litter size of Chinese Meishan pigs have given widely divergent results depending on the extent of inbreeding of the animals, their original genetic diversity, the age and parity, and the conditions of management. To obtain meaningful results, it is necessary to characterize the population under study. The following report characterizes populations of Meishan and Yorkshire of a widely diverse background. First farrowing data were collected on 21 Meishan and 20 Yorkshire gilts. Meishan gilts had 12.4 fully formed piglets and Yorkshire gilts had 7.4 fully formed piglets (P < 0.01). Meishan gilts averaged 1.86 mummified fetuses per litter vs 0.05 per Yorkshire litter (P < 0.01). Yorkshire piglets averaged 1.3 kg body weight at birth vs 0.9 kg for Meishan piglets (P < 0.01). At 47 days of second gestation, 19 Meishan and 12 Yorkshire sows averaged 22.7 and 16.3 corpora lutea (CL), respectively (P < 0.01). Uterine length and number of fetuses were not different (P > 0.40) in the two breeds. Daily estrous detection of 50 Meishan and 34 Yorkshire gilts began at 60 and 120 days of age, respectively. Meishan gilts reached sexual maturity at 95 days of age, which was 105 days earlier than Yorkshire gilts (P < 0.01). Meishan gilts were in estrus nearly 1 day longer than Yorkshire gilts at first, second and third estrus (P < 0.05). No differences in cycle length between breeds were detected for the first or second estrous cycle (P > 0.60). Nineteen Meishan gilts were slaughtered at 51 days of gestation and their reproductive tracts were recovered. The mean number of dissected CL (17.0), number of fetuses (13.1), total uterine length (396 cm), spacing per fetus (29.9 cm), allantoic (124.9 ml) and amniotic (32.2 ml) volumes, crown-rump length (82.8 mm), weight (35.4 g), sex, and direction of each fetus were determined. Chinese Meishan gilts reached puberty much earlier and were in estrus longer than Yorkshire gilts and Meishan sows had more CL than Yorkshire sows.     

Production and composition of Iberian sow's milk and use of milk nutrients by the suckling Iberian piglet

Sixteen purebred Iberian (IB) sows were used in two consecutive trials to determine the efficiency of conversion of sow's milk into piglet body weight (BW) gain and the relationship between milk protein and body protein retention and between milk energy yield and body energy retention in the nursing IB piglet. In each trial, four sows were selected in order to evaluate their milk production, litter growth and nutrient balance measurements, together with four additional sows for milk sampling. Litter size was equalized to six piglets. Daily milk yield (MY) was determined weekly by the weigh-suckle-weigh technique over a 34-day lactation period. Piglets were weighed individually at birth and then weekly from day 5 of lactation. Milk samples were collected on days 5, 12, 19, 26 and 34 post partum. The comparative slaughter procedure was used to determine piglet nutrient and energy retention. One piglet from each litter was slaughtered at birth and four on the morning of day 35. Total MY was on average 5.175 ± 0.157 kg/day. The average chemical composition (g/kg) of the milk was 179 ± 4 dry matter, 53.4 ± 1.0 CP, 58.5 ± 3.8 fat, 10.4 ± 0.3 ash and 56.9 ± 2.3 lactose. Milk gross energy (GE) was 4.626 ± 0.145 MJ/kg. Milk intake per piglet tended to increase in trial 2 (832 v. 893 g/day; P = 0.066). Piglet BW gain contained (g/kg) 172.1 ± 1.3 protein, 151.5 ± 3.5 fat, 41.4 ± 0.6 ash and 635 ± 3 water and 10.127 ± 0.126 MJ GE/kg. Throughout the 34-day nursing period, the piglets grew at an average rate of 168 ± 3 g/day. The ratio of daily piglet BW gain to daily MY was 0.195 ± 0.002 g/g and the gain per MJ milk GE intake was 41.9 ± 0.5 g/MJ. The overall efficiency of protein accretion (g CP gain/g CP milk intake) was low and declined in trial 2 (0.619 v. 0.571; P = 0.016). Nutrient and energy deposition between birth and weaning were 27.4 ± 0.5 g/day protein, 24.2 ± 0.8 g/day fat and 1615 ± 40 kJ/day energy. Piglet energy requirements for maintenance were 404 kJ metabolizable energy (ME)/kg BW0.75. ME was used for growth with a net efficiency of 0.584. These results suggest that poor efficiency in the use of sow's milk nutrients rather than a shortage in milk nutrient supply might explain the low growth rate of the suckling IB piglet.     

Sows with high milk production had both a high feed intake and high body mobilization

Selection for increased litter size have generated hyper-prolific sows that nurses large litters, however limited knowledge is available regarding the connection between milk production, feed intake and body mobilization of these modern sows. The aim of the current study was to determine what characterized sows with high milk production and nursing large litters, differences between sows of different parities and effects of lactational performance on next reproductive cycle. In total 565 sows (parity 1 to 4) were studied from 7 days before farrowing until weaning. On day 2 postpartum litters were standardized to 14 piglets. Weight and back fat thickness of sows were measured at day 7 prepartum, day 2 postpartum and at weaning. Litters were weighed at day 2 and at weaning. Pearson correlation coefficients between variables were calculated and regression models were developed. The average daily feed intake (ADFI) of the sows was 6.1±1.1 kg/day, average daily gain (ADG) of the litter was 2.92±0.53 kg/day and sows weaned 13.0±1.1 piglets. First parity sows generally had a lower ADFI and milk production and a decrease in total born piglets in next litter compared with parity 2 to 4 sows, which could be explained by a relatively higher proportion of their body reserves being mobilized compared with multiparous sows. The ADG of the litter was positively related by ADFI of the sows, litter size and BW loss and increasing the ADFI with 1 kg/day throughout lactation likely increased the ADG of the litter with 220 to 440 g/day in parity 1 to 4, respectively. Increasing the ADFI by 1 kg/day reduced the BW loss with 6.6 to 13.9 kg of parity 1 to 4 sows, respectively, during lactation, whereas increasing the average milk yield with 1 kg/day raised the BW loss with 4.3 to 21.0 kg of the four parities during lactation. The number of total born piglets in the next litter was positively related to the number of piglets born in the previous litter. In conclusion, both a high feed intake and a high mobilization of body reserves was a prerequisite for a high milk production. The sows might be very close to the physical limit of what they can ingest and future research should therefore, focus on optimizing the dietary energy and nutrient concentrations of diets for lactating hyper-prolific sows and herein distinguish between primiparous and multiparous sows.     

Age, body weight and backfat thickness at first observed oestrus in crossbred Landrace x Yorkshire gilts, seasonal variations and their influence on subsequence reproductive performance

The objective of the present study was to investigate puberty attainment in crossbred Landrace x Yorkshire (LY) gilts reared under tropical conditions and their subsequent reproductive performance. This study was carried out in a 2400-sow herd over a 1-year period. A total of 696 crossbred LY replacement gilts were included. Faecal samples from 214 gilts were collected to determine the faecal progesterone profiles around the time of first oestrus. Solid-phase 125I-radioimmunoassay was used to determine the progesterone concentrations in the faecal extract. The gilts entered the herd at an average age of 177.5 +/- 12.6 days, 95.7 +/- 10.2 kg body weight (BW) and a backfat thickness (BF) of 12.0 +/- 2.9 mm. On average, the gilts expressed first standing oestrus at 195 days of age, 106 kg of BW and a BF of 13.0 mm. The interval from entry to the gilt pool to the first observed oestrus (EOI) was 24.4 +/- 18.0 days (range 0-88 days). The hormonal profile indicated that the gilts that actually ovulated during the first observed oestrus was 34% (group A), the gilts that had ovulated before the first observed oestrus was 21% (group B) and the gilts that did not ovulate during the first observed oestrus was 45% (group C). During summer the proportion of group A gilts was significantly lower than during the winter and the rainy seasons (P < 0.05). The BW of gilts at entry significantly correlated with the BF at entry (r = 0.31, P < 0.001), the age at entry (r = 0.47, P < 0.001), the BW at first oestrus (r = 0.65, P < 0.001) and the BF at first oestrus (r = 0.33, P < 0.001). An increase of BW at entry of 1 kg resulted in a decrease of EOI of 0.28 days. The age, BW and BF of gilts at the first observed oestrus significantly influenced the total number of piglets born per litter (TB) and the number of piglets born alive per litter (BA) in the first three parities. Gilts expressing their first oestrus between 181 and 200 days had a significantly larger TB than gilts that expressed first oestrus between 150 and 180 days (P = 0.03) and between 201 and 220 days (P = 0.003). Gilts that showed first oestrus between 110.1 and 120.0 kg had a larger TB and BA than gilts that showed first oestrus between 80.0 and 100.0 kg (P < 0.05). Gilts that showed first oestrus with a BF between 13.1 and 15.0 mm had a larger TB and BA than gilts that showed first oestrus with a BF between 11.1 and 13.0 mm (P < 0.05). Group A gilts had a significantly larger TB than group B (10.5 piglets/L versus 9.4 piglets/L, P = 0.02), while farrowing rate (FR) did not differ significantly among groups A, B and C (78.1, 76.9 and 77.6%, respectively). Gilts that farrowed in the summer had a larger TB and BA than gilts that farrowed in the winter (TB, P = 0.03; BA, P = 0.09) and the rainy season (TB, P = 0.006; BA, P = 0.003). In conclusion, LY gilts reared under tropical conditions expressed first standing oestrus at 195 days of age, 106 kg BW and a BF of 13.0 mm. Under field conditions, 21% of the gilts with an observed oestrus had ovulated. The proportion of gilts that showed first oestrus and ovulated normally was lowest during the summer. The age, BW and BF at first observed oestrus influenced subsequent reproductive performance over the first three parities. The mean litter size (TB and BA) in the first three parities were highest in gilts that had a first observed oestrus between 181 and 200 days with 110.1-120.0 kg BW and 13.1-15.0 mm BF.     

Productive performance, carcass and meat quality of intact and castrated gilts slaughtered at 106 or 122 kg BW

A total of 200 (Landrace × Large White dam × Pietrain × Large White sire) gilts of 50 ± 3 days of age (23.3 ± 1.47 kg BW) were used to investigate the effects of castration (intact gilt, IG v. castrated gilt, CG) and slaughter weight (SW; 106 v. 122 kg BW) on productive performance, carcass and meat quality. Four treatments were arranged factorially and five replicates of 10 pigs each per treatment. Half of the gilts were ovariectomized at 58 days of age (8 days after the beginning of the trial at 29.8 ± 1.64 kg BW), whereas the other half remained intact. The pigs were slaughtered at 106 or 122 kg BW. Meat samples were taken at Musculus longissimus thoracis at the level of the last rib and subcutaneous fat samples were taken at the tail insertion. For the entire experimental period, CG had higher (P < 0.05) BW gain and higher (P < 0.001) backfat and Musculus gluteus medius fat thickness than IG. However, IG had higher (P < 0.05) loin and trimmed primal cut yields than CG. Meat quality was similar for IG and CG but the proportion of linoleic acid in subcutaneous fat was higher (P < 0.001) for IG. Pigs slaughtered at 122 kg BW had higher (P < 0.001) feed intake and poorer feed efficiency than pigs slaughtered at 106 kg BW. An increase in SW improved (P < 0.001) carcass yield but decreased (P < 0.05) trimmed primal cut yield. Meat from pigs slaughtered at the heavier BW was redder (a*; P < 0.001) and had more (P < 0.01) intramuscular fat and less thawing (P < 0.05) and cooking (P < 0.10) loss than meat from pigs slaughtered at the lighter BW. In addition, pigs slaughtered at 122 kg BW had less (P < 0.01) linoleic acid content in subcutaneous fat than pigs slaughtered at 106 kg BW. Castration of gilts and slaughtering at heavier BW are useful practices for the production of heavy pigs destined to the dry-cured industry in which a certain amount of fat in the carcass is required. In contrast, when the carcasses are destined to fresh meat production, IG slaughtered at 106 kg BW is a more efficient alternative.     

A retrospective study on the preserving capacity of a commercial boar semen extender

The objective of this study was to evaluate the preserving capacity of a commercial, long-term boar semen extender beyond 4 days in terms of farrowing failure and total born per litter in sows and gilts. Data from 21 farms were subjected to logistic and linear regression analyses to assess the effect of parity (2-5, > 5 and gilts), wean-to-service interval (/= 6 days) and number of AI (1, 2, or 3) on the association between semen age (/=10 days) and fertility. As the semen age increased, the likelihood of farrowing failure increased and total born per litter decreased in sows and gilts. The effect of semen ageing on farrowing failure was more pronounced in sows than in gilts as in the latter it became significant only after 8 days. The effect of semen ageing on total born per litter was similar in both sows and gilts. A lower parity and wean-to-service interval were associated with a reduction in farrowing failure and increase in total born per litter in sows. Increasing the number of inseminations up to two was beneficial in reducing farrowing failure in sows and gilts. A third insemination increased the likelihood of farrowing failure in sows. The number of total born per litter in sows increased with number of inseminations and the effect was not significant in gilts.     

Absence of brain opioid peptide modulation of luteinizing hormone secretion in the prepubertal gilt

Three experiments were conducted to evaluate the role of endogenous opioid peptides (EOP) in modulating luteinizing hormone (LH) secretion in the prepubertal gilt. In Experiment I, 8 prepubertal (P) gilts, 160-170 days of age (puberty = 197 +/- 10 days), received either 1 (n = 2), 3 (n = 3), or 6 (n = 3) mg/kg BW of naloxone (NAL), an opiate antagonist, in saline i.v. Blood was collected by jugular vein cannula every 15 min for 2 h before and 2 h after NAL. All doses of NAL failed to alter serum LH concentrations. In Experiment II, 21 P gilts 160-170 days of age and 21 mature (M) gilts were ovariectomized (OVX). At the time of OVX, gilts were classified as prepubertal if their ovaries were devoid of corpora albicantia and corpora lutea. Three weeks after OVX, P and M gilts were injected twice daily for 10 days with either 0.85 mg/kg BW of progesterone (P4) or oil vehicle (V), resulting in the following groups: PP4 (n = 11), PV (n = 10), MP4 (n = 11), and MV (n = 10). All gilts received 1 mg/kg BW of NAL on the last day of treatment. Blood samples were collected via a jugular cannula every 15 min for 4 h before and 2 h after NAL treatment. NAL treatment resulted in an increase (p less than 0.05) in serum LH concentrations only in the MP4 gilts. In Experiment III, 15 OVX gilts 280 days of age were used. Ten of the 15 gilts were OVX prior to puberty at 160 days of age and were classified as chronologically mature (CM) at the time of treatment. The remaining 5 gilts were OVX after puberty, and were classified as sexually mature (SM) at the time of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of birth litter size, birth parity number, growth rate, backfat thickness and age at first mating of gilts on their reproductive performance as sows

The present study was performed to evaluate retrospectively the influence of birth litter size, birth parity number, performance test parameters (growth rate from birth to 100kg body weight and backfat thickness at 100kg body weight) and age at first mating (AFM) of gilts on their reproductive performance as sows. Traits analysed included remating rate in gilts (RRG), litter size, weaning-to-first-service interval (WSI), remating rate in sows and farrowing rate (FR). Data were collected from 11 Swedish Landrace (L) and 8 Swedish Yorkshire (Y) nucleus herds and included 20712 farrowing records from sow parities 1-5. Sows that farrowed for the first time during 1993-1997, having complete records of performance test and AFM, were followed up to investigate their subsequent reproductive performance until their last farrowing in 1999. Analysis of variance and multiple regression were applied to continuous data. Logistic regression was applied to categorical data. The analyses were based on the same animals and the records were split into six groups of females, i.e. gilts, primiparous sows, and sows in parities 2-5, respectively. Each additional piglet in the litter in which the gilt was born was associated with an increase of her own litter size of between 0.07 and 0.1 piglets per litter (P<0.001). Gilts born from sow parity 1 had a longer WSI as primiparous sows compared with gilts born from sow parity 4 (0.3 days; P<0.05) or parity 5 (0.4 days; P<0.01). Gilts with a higher growth rate of up to 100kg body weight had a larger litter size (all parities 1-5; P<0.05), shorter WSI (all parities 1-5; P<0.05) and higher FR (parities 2 and 5; P<0.05) than gilts with a lower growth rate. Gilts with a high backfat thickness at 100kg body weight had a shorter WSI as primiparous sows (P<0.001) compared with low backfat gilts, and 0.1 piglets per litter more as second parity sows (P<0.01). A 10 day increase in AFM resulted in an increase in litter size of about 0.1 piglet for primiparous sows (P<0.001) and a decrease (P<0.05) for sow parities 4 and 5.     

Contribution of the wheat (Triticum aestivum L.) flag leaf to grain yield in response to plant growth regulators

In West-Europe, intensive cereal management uses plant growth regulators (PGRs) especially for wheat. A green-house experiment compared the effects of two PGRs on flag leaf characteristics and yield of winter wheat. Chlormequat chloride + choline chloride (CCC) and chlormequat chloride + choline chloride + imazaquin (CCC+I) were applied to winter wheat at growth stage 5 (Feekes Large scale). CCC and CCC+I significantly increased flag leaf surface area at anthesis. Both treatments also enhanced chlorophyll content of the main stem flag leaf. The grain filling period was extended with PGR application by 2 days. CCC and CCC+I significantly increased net CO₂ assimilation rates during the flag leaf life. No effects of PGR spraying were observed on the pattern of ¹⁴C labelled assimilate distribution. Increased grain yield was due to the increase in average grain weight. The results indicate that PGR treatments increased flag leaf contribution to grain filling. The addition of imazaquin (I) to chlormequat (CCC) improved the effects of CCC.     

Effects of konjac flour inclusion in gestation diets on the nutrient digestibility,lactation feed intake and reproductive performance of sows

This study was conducted to investigate the effects of konjac flour (KF) inclusion in gestation diets of sows on nutrients digestibility, lactation feed intake, reproductive performance of sows and preweaning performance of piglets. Two isoenergetic and isonitrogenous gestation diets were formulated: a control diet and a 2.1% KF-supplemented diet (KF diet). Both diets had the same NDF and insoluble fiber (ISF) levels, but the KF diet had higher soluble fiber (SF) level. The day after breeding, 96 multiparous sows were assigned to the two dietary treatments. Restrict-fed during gestation, in contrast, all sows were offered the same lactation diet ad libitum. Response criteria included sow BW, backfat depth, lactation feed intake, weaning-to-estrus interval, litter size and piglet’s weight at parturition and day 21 of lactation. On day 60 of gestation, 20 sows were used to measure nutrient digestibility. Results showed that the digestibility of dry matter, gross energy, crude fiber and ADF were not affected by the dietary treatments. The inclusion of KF in gestation diets increased NDF digestibility (P<0.05) and tended to increase the digestibility of CP (P=0.05) compared with the control diet group. In addition, dietary treatment during gestation did not affect litter size, BW and backfat gain during gestation, lactation weight, backfat loss or weaning-to-estrus interval of sows. However, sows fed the KF diet consumed more (P<0.05) lactation diet per day than sows in the control group. Accordingly, sows fed the KF diet showed greater average piglet weights on day 21 of lactation (P=0.09), and the litter weight of sows fed the KF diet on day 21 of lactation increased by 3.95 kg compared with sows fed the control diet (not significant). In conclusion, the inclusion of KF in gestation diets increased lactation feed intake of sows and tended to improve litter performance.     

Effects of two different anaesthetics on serum concentrations of cortisol and luteinizing hormone in barrows and gilts

To determine if administration of the anaesthetic cocktail, telazol-ketamine-xylazine (TKX) and pentothal (PEN) decreases serum concentrations of luteinizing hormone (LH) in pigs, the following experiment was performed. On day 1, eight gilts and six barrows of similar weight (75 kg) were anaesthetized with TKX (1 mL/22.5 kg body weight [BW] intramuscularly) and indwelling jugular catheters were inserted. On days 2, 6 and 8 blood samples were taken every 20 min, for 4 h before pigs were administered saline (day 2) or anaesthetized with TKX (day 6) and PEN (8.9 mg/kg BW intravenously, day 8). Blood samples were taken every 20 min for 4 h following administration of saline and anaesthetics. Mean serum concentrations of LH and cortisol did not differ (P > 0.05) within barrows or gilts from before administration of saline (day 2) to following saline administration. Mean serum concentrations of LH and cortisol were not different (P > 0.05) within barrows and gilts before administration of TKX (pre-TKX) or PEN compared with day 2 samples. Following administration of TKX (post-TKX), mean serum concentrations of LH decreased (P < 0.05) and remained decreased for 140 min, while mean serum concentrations of cortisol increased (P < 0.05) post-TKX and remained elevated for 140 min. In gilts, mean serum concentrations of LH did not differ (P > 0.05) from pre- to post-TKX. However, mean serum concentrations of cortisol increased (P < 0.05) post-TKX in gilts and remained elevated for 240 min. Following administration of PEN, mean serum concentrations of LH and cortisol within barrows and gilts were not different (P > 0.05) from concentrations before administration of PEN. Administration of TKX to barrows and gilts increased serum concentrations of cortisol, but transient decreases in serum concentrations of LH were observed only in barrows, indicating gonadal status and/or sex may influence the ability of TKX to alter circulating concentrations of LH in pigs.     

The association between growth rate, body weight, backfat thickness and age at first observed oestrus in crossbred Landrace x Yorkshire gilts

The present study aims to investigate the association between growth rate (GR), body weight (BW), backfat thickness (BF) and age at first observed oestrus in crossbred Landrace x Yorkshire (LY) replacement gilts in the tropics. The study was carried out on five commercial swine herds in Thailand between 2004 and 2006. A total of 6946 LY gilts were included. The gilts entered the herd at about 163 days of age. The BW (kg) and BF (mm) of the gilts were measured when the gilts entered the gilt pools and again when the gilts were sent to the breeding house. The GR from birth to entry into the gilt pools (birth to 90 kg BW) (GRe), the GR from entry into to exit from the gilt pools (91-134 kg BW) (GRi) and the GR from birth until the gilts were sent to the breeding house (birth to 134 kg BW) (GRs) were calculated. The relationship between age at first observed oestrus and GRe, GRs, GRi, BW and BF were analyzed. Pearson's correlation and four general linear models (GLMs) were conducted. On average, the gilts showed first observed oestrus at 200+/-28 days of age. The means of age at first observed oestrus varied from 188 to 251 days (P<0.001) among the herds. The GRs of the gilts significantly correlated with the BW (r=0.55, P<0.001) of the gilts when they were sent to the breeding house and the age at first observed oestrus (r=-0.40, P<0.001). Gilts with a high GRe and GRs were younger at first observed oestrus compared to gilts with a low GRe and GRs. On average, the gilts with GRs of over 604 g/day showed first observed oestrus before 5 months of age. GRi was not correlated with the age at first observed oestrus (P>0.05). Neither the BF of the gilts at entry nor the BF that the gilts gained within the gilt pools significantly correlated with age at first observed oestrus (P=0.29 and P=0.69, respectively). But the gilts with a higher BF at entry tended to have a higher BW when they were sent to the breeding house (r=0.44, P<0.001). The present study indicates that replacement gilts with a high GR (both GRe and GRs) tend to show sign of oestrus earlier than gilts with a low GR (both GRe and GRs).     

Responses to n-3 fatty acid (LCPUFA) supplementation of gestating gilts,and lactating and weaned sows

Feeding n-3 long-chain polyunsaturated fatty acids (LCPUFA) to gilts or sows has shown different responses to litter growth, pre-weaning mortality and subsequent reproductive performance of the sow. Two hypotheses were tested: (1) that feeding a marine oil-based supplement rich in protected n-3 LCPUFAs to gilts in established gestation would improve the growth performance of their litters; and (2) that continued feeding of the supplement during lactation and after weaning would offset the negative effects of lactational catabolism induced, using an established experimental model involving feed restriction of lactating primiparous sows. A total of 117 primiparous sows were pair-matched at day 60 of gestation by weight, and when possible, litter of origin, and were allocated to be either control sows (CON) fed standard gestation and lactation diets, or treated sows (LCPUFA) fed the standard diets supplemented with 84 g/day of a n-3 LCPUFA rich supplement, from day 60 of first gestation, through a 21-day lactation, and until euthanasia at day 30 of their second gestation. All sows were feed restricted during the last 7 days of lactation to induce catabolism, providing a background challenge against which to determine beneficial effects of n-3 LCPUFA supplementation on subsequent reproduction. In the absence of an effect on litter size or birth weight, n-3 LCPUFA tended to improve piglet BW gain from birth until 34 days after weaning (P = 0.06), while increasing pre-weaning mortality (P = 0.05). It did not affect energy utilization by the sow during lactation, thus not improving the catabolic state of the sows. Supplementation from weaning until day 30 of second gestation did not have an effect on embryonic weight, ovulation rate or early embryonic survival, but did increase corpora lutea (CL) weight (P = 0.001). Eicosapentaenoic acid and docosahexaenoic acid (DHA) levels were increased in sow serum and CL (P < 0.001), whereas only DHA levels increased in embryos (P < 0.01). In conclusion, feeding n-3 LCPUFA to gilts tended to improve litter growth, but did not have an effect on overall subsequent reproductive performance.     

Development of bone mineralization and body composition of replacement gilts fed a calcium and phosphorus depletion and repletion strategy

This study investigated the ability of replacement gilts to adapt their calcium and phosphorus utilization and their kinetics in bone mineralization to compensate for modified intake of these nutrients by applying a novel Ca and P depletion and repletion strategy. A total of 24 gilts were fed according to a two-phase feeding program. In the first phase, gilts (60–95 kg BW) were fed ad libitum a depletion diet providing either 60% (D60; 1.2 g digestible P/kg) or 100% (D100; 2.1 g digestible P/kg) of the estimated P requirement. In the second phase, gilts (95–140 kg BW) were fed restrictively (aim: 700–750 g/d BW gain) a repletion diet. Half of the gilts from each depletion diet were randomly assigned to either a control diet or a high-P diet (R100 and R160; with 2.1 and 3.5 g digestible P/kg, respectively) according to a 2 × 2 factorial design, resulting in four treatments: D60-R100, D60-R160, D100-R100 and D100-R160. Dual-energy X-ray absorptiometry was used to measure whole-body bone mineral content (BMC), bone mineral density (BMD) and lean and fat tissue mass on each gilt at 2-week intervals. The depletion and repletion diets, fed for 5 and 8 weeks, respectively, did not influence growth performance. The D60 gilts had a reduced BMC and BMD from the second week onwards and ended (95 kg BW) with 9% lower values than D100 gilts (P < 0.001). During repletion, D60 gilts completely recovered the deficit in bone mineralization from the second and fourth week onwards, when fed R160 (D60-R160 vs D100-R160) or R100 (D60-R100 vs D100-R100) diets, respectively (treatment × time interaction, P < 0.001); thus, the depletion diets did not affect these values at 140 kg BW. These results illustrate the rapid homeostatic counter-regulation capacity of dietary Ca and P, and they show the high potential to limit dietary digestible P concentration by completely excluding the use of mineral phosphates during the depletion phase, representative of the fattening period, without causing any detrimental effects to gilts at mating. The gilts were able to recover their BMC deficit between their selection at 95 kg BW and first mating at 140 kg BW by increasing their dietary Ca and P efficiency. Finally, excess dietary digestible P, requiring increased amounts of mineral phosphates, further increased the gilts’ BMC.     

Impact of feed restriction on the performance of highly prolific lactating sows and its effect on the subsequent lactation

A total of 50 mixed parity sows of a high-prolificacy genetic line were used to evaluate the impact of feed restriction during lactation on their production and reproductive performance and their performance in the subsequent lactation. From day 7 of lactation, sows were distributed according to a completely randomized experimental design into two treatments. In treatment 1, sows were fed 8.0 kg feed/day (control) and in treatment 2, sows were fed 4.0 kg/day. The same suckling pressure was maintained until weaning on day 28 of lactation. Average minimum and maximum temperatures measured during the experimental period were 32.1°C and 16.5°C, respectively. Control sows presented significantly higher feed intake (P<0.001) compared with the restricted sows (6.43 v. 4.14 kg/day, respectively). Treatments influenced BW and backfat thickness losses (P<0.001). Control sows lost less BW than the restricted-fed sows (7.8 v. 28.2 kg). Restricted-fed sows lost more backfat thickness than those in the control group (3.97 v. 2.07 mm; P<0.01). Restricted-fed sows tended (P<0.10) to be lighter at weaning compared with the control sows (211 v. 227 kg). The composition of BW loss was influenced by the treatments (P<0.001), as the restricted-fed sows lost more body protein, lipids and energy compared with the control sows (3.90 v. 0.98 kg, 11.78 v. 4.83 kg and 584 v. 224 MJ, respectively). Litter weight gain was greater (P<0.05) in control sows than in restricted-fed sows (2.70 v. 2.43 kg/day). Daily milk production was 19% higher (P<0.01) in the control sows compared with the restricted-fed sows (8.33 v. 6.99 kg/day). However, restricted-fed sows presented a higher (P<0.05) lactation efficiency than the sows of the control group (82.30% v. 72.93%). No differences were detected (P>0.10) in weaning-to-estrus interval and averaged 4.3 days. No effect of the treatment (P>0.10) was observed on any of the studied performance traits in the subsequent lactation, except for litter size at birth that tended (15.2 v. 14.1; P<0.10) to be lower for the restricted sows. In conclusion, the present study demonstrated that feed restriction during lactation leads to intense catabolism of the body tissues of sows, negatively affecting their milk production, and the litter weight gain and possibly number of piglets born in the next litter. On the other hand, restricted-fed sows are more efficient, producing more milk per amount of feed intake.     

Embryo survival, progesterone profiles and metabolic responses to an increased feeding level during second gestation in sows

This study describes reproductive and metabolic responses in sows fed at two different feeding levels from day 3-35 of second gestation. After insemination, 37 sows were assigned to one of two treatments: 1) Control: 2.5 kg/day of a gestation diet; 2) Plus Feed 3.25 kg/day of a gestation diet (+30%). Sow weight, back fat and loin muscle depth were measured at farrowing, weaning, start of treatment, day 14 after start treatment and end of treatment. Frequent blood samples were taken for progesterone, luteinizing hormone (LH), glucose and insulin, insulin-like-growth-factor-1 (IGF-1), non-esterified-fatty-acids (NEFA) and urea analysis. At day 35 after insemination sows were euthanized and their reproductive tract collected to assess ovarian, embryonic and placental characteristics. Plus Feed sows gained 5.4 kg more weight and 0.9 mm more back fat and tended to be heavier at slaughter compared to Control sows (193 vs. 182 kg, P = 0.06). No difference in loin muscle gain was found. Treatment also did not affect vital embryonic survival, which was 72.1 ± 3.9% for Control and 73.4 ± 3.2% for Plus Feed sows, resulting in, respectively, 15.9 ± 0.9 and 15.7 ± 0.7 vital embryos. No effect of treatment on any of the ovarian, embryonic or placental characteristics was found. Progesterone profiles during the first month of gestation, and LH characteristics at day 14 of gestation were not different between treatments. Progesterone concentration was lower (P < 0.05) 3 h after feeding compared with the prefeeding level on days 7-11 after first progesterone rise for Plus Feed and on days 8-10 after first progesterone rise for Control sows. At day 15, preprandial glucose and insulin concentrations were not different between treatments, insulin peaked later (48 vs. 24 min) and at a higher concentration in Plus Feed than in Control sows. Furthermore, glucose area under the curve (AUC) tended to be lower (−171.7 ± 448.8 vs. 1257.1 ± 578.9 mg/6.2 h, P = 0.06, respectively) for Plus Feed vs. Control sows. IGF-1 concentration was not different between treatments, but NEFA concentrations were lower for Plus Feed vs. Control sows (149.5 ± 9.2 vs. 182.4 ± 11.9 μm/L, respectively, P = 0.04) and urea concentration tended to be higher in Plus Feed than in Control sows (4.3 ± 0.1 vs. 3.9 ± 0.1, respectively, P = 0.13). None of the metabolic parameteres were related to reproductive measures. In conclusion, feeding 30% more feed from day 3 till d 35 of second gestation increased weight gain and resulted in lower NEFA concentrations, but did not affect progesterone, LH or IGF-1 and embryonic and placental characteristics.     

Deposition of copper, iron, manganese and zinc in the empty body of growing lambs of the breed German Merino Landsheep

A growth experiment with 108 lambs (breed: German Merino Landsheep) was carried out to examine the effect of gender, body weight (BW) and feeding intensity on the deposition of Fe, Zn, Cu and Mn in the empty body (whole animal minus contents of the gastrointestinal tract and bladder). The lambs (50% female and 50% male animals) were fed at three feeding levels ('low', 'medium' and 'high' by varying daily amounts of concentrate and hay) and slaughtered at different final BWs (30, 45 or 55 kg). Six male and six female animals were killed at a BW of 18 kg representing the animals' BW at the beginning of the comparative slaughter experiment. There were significant main effects for the treatments growth rate and final weight on the daily rate of accretion of the trace elements examined. Feeding intensity had a marked influence on the accretion rate for Fe (P < 0.001), Zn (P < 0.001), Cu (P < 0.001) and Mn (P = 0.003). With increasing feeding intensity (low, medium, high) the daily deposition of these trace elements increased (4.4, 5.2, 6.6 mg/day for Fe; 4.9, 5.5, 6.9 mg/day for Zn; 0.20, 0.36, 0.44 mg/day for Cu; 0.14, 0.16, 0.21 mg/day for Mn). Heavier final BW led to increased daily retention of Zn (P < 0.001) and Mn (P = 0.002). Gender had a marked influence only on the accretion rate for Zn (P < 0.001). Ram lambs had a higher daily deposition of this element than female lambs. Related to 1000 g empty body gain, the following concentrations were found for the trace elements examined: Fe 26.1 mg, Zn 30.0 mg, Cu 1.41 mg and Mn 1.04 mg. A feeding influence was given for Zn (P < 0.001) and Cu (P = 0.039). Feeding level low had higher Zn and lower Cu concentrations. Male animals showed less Fe (P < 0.001) and Zn (P = 0.034) per kg empty body gain than females.