Lysine requirements of finishing boars and gilts: A meta-analysis

The expected increase in boar (pig entire male) production while societal concerns for castration increase requires good estimations of their nutrient requirements. In this work, a meta-analytical approach was used to overcome the inconsistent results between studies that compared lysine requirements of boars and gilts. For this meta-analysis, data from 14 different studies analysing the effect of increasing dietary lysine on growth performance of finishing pigs, 70–100 kg average body weight, were extracted from 11 publications. Those studies represented 128 different treatments (53 for boars and 75 for gilts). Diets were reformulated based on NRC (2012) ingredient values to calculate standardized ileal digestible lysine to net energy ratio (SID Lys:NE) and daily SID Lys intake using average daily feed intake (ADFI). As expected, no evidence for differences in ADFI (P = 0.303) was observed between boars and gilts. However, boars grew faster (P < 0.001) and had higher gain to feed (G:F; P < 0.001). The divergent effect of SID Lys:NE on average daily gain (ADG) and G:F was analysed in a quadratic polynomial model showing different parameters for each sex (P < 0.001). Although performance between sexes was similar at low SID Lys:NE, differences were greater at higher SID Lys:NE. Furthermore, broken-line linear, broken-line quadratic (BLQ) and quadratic polynomial (QP) models were fitted to each sex to determine SID Lys:NE and SID Lys daily intake requirements to maximize ADG and G:F. Overall, QP models showed the best fit, and reported that to reach maximum ADG 0.88 (95% CI:[0.82–0.94]) or 1.01 (95% CI:[0.91–1.11]) g SID Lys/MJ, NE was required for gilts and boars, respectively. However, boar ADG was best fitted by BLQ using SID Lys daily intake as independent variable, with the requirement for maximum ADG at 24.2 (95% CI:[21.3–27.2]) g SID Lys/day. The three models reported wide confidence intervals for the requirements at maximum performance, and consequently those were overlapped when comparing boars and gilts. Maximum boars’ productive performance when dietary lysine was not limiting was 116% of gilts, and at those levels the amount of SID Lys intake required per kg gain was similar between both sexes. Thus, because ADFI and Lys efficiency of gain was similar, the requirement differences were driven by the increased growth rate and gain to feed ratio between boars and gilts. In conclusion, the present study confirmed a greater productive response of boars compared to gilts when increasing dietary lysine.     

Genome-Wide Association Study Reveals Genetic Architecture of Eating Behavior in Pigs and Its Implications for Humans Obesity by Comparative Mapping

This study was aimed at identifying genomic regions controlling feeding behavior in Danish Duroc boars and its potential implications for eating behavior in humans. Data regarding individual daily feed intake (DFI), total daily time spent in feeder (TPD), number of daily visits to feeder (NVD), average duration of each visit (TPV), mean feed intake per visit (FPV) and mean feed intake rate (FR) were available for 1130 boars. All boars were genotyped using the Illumina Porcine SNP60 BeadChip. The association analyses were performed using the GenABEL package in the R program. Sixteen SNPs were found to have moderate genome-wide significance (p<5E-05) and 76 SNPs had suggestive (p<5E-04) association with feeding behavior traits. MSI2 gene on chromosome (SSC) 14 was very strongly associated with NVD. Thirty-six SNPs were located in genome regions where QTLs have previously been reported for behavior and/or feed intake traits in pigs. The regions: 64–65 Mb on SSC 1, 124–130 Mb on SSC 8, 63–68 Mb on SSC 11, 32–39 Mb and 59–60 Mb on SSC 12 harbored several signifcant SNPs. Synapse genes (GABRR2, PPP1R9B, SYT1, GABRR1, CADPS2, DLGAP2 and GOPC), dephosphorylation genes (PPM1E, DAPP1, PTPN18, PTPRZ1, PTPN4, MTMR4 and RNGTT) and positive regulation of peptide secretion genes (GHRH, NNAT and TCF7L2) were highly significantly associated with feeding behavior traits. This is the first GWAS to identify genetic variants and biological mechanisms for eating behavior in pigs and these results are important for genetic improvement of pig feed efficiency. We have also conducted pig-human comparative gene mapping to reveal key genomic regions and/or genes on the human genome that may influence eating behavior in human beings and consequently affect the development of obesity and metabolic syndrome. This is the first translational genomics study of its kind to report potential candidate genes for eating behavior in humans.     

Influence of sex and immunocastration on feed intake behavior,skatole and indole concentrations in adipose tissue of pigs

Feed intake behavior was studied between 9 weeks of age and slaughter in a total of 36 gilts, 32 immunocastrates, 33 surgically castrated barrows and 33 boars from 36 litters. Consequences for the concentration of substances contributing to off odor of pork (skatole, indole) were evaluated. Animals were kept in groups of 12 pigs of the same sex and treatment and fed ad libitum (13.4 MJ ME, 17% CP, 1.1% lysine). Individual feed intake behavior was recorded continuously by an electronic feeder. Immunocastration was carried out with two injections of Improvac with at least 4 weeks between both injections (1st: 12 to 17 weeks of age, 2nd: 19 to 21 weeks of age). Feed intake/day increased from an average of 0.91 ± 0.02 kg/day up to 3.15 ± 0.04 kg/day before slaughter. This increase was associated with a 50% reduction in the number of meals/day (from 15.8 ± 0.44 to 7.2 ± 0.29 meals/day). The larger meal sizes resulted from an increase in both, the duration of feed intake/meal and the feed intake rate (g/min). In addition, sex and treatment differences were observed: Feed intake in boars was lower than in all other groups due to a reduction in the number of meals/day and in the time spent feeding/day. In females, time spent feeding/day was quite similar to boars, but resulted from a higher number of meals of shorter duration. Barrows had a significantly higher feed intake because of a higher number of meals/day resulting in more time spent feeding/day. The feed intake rate was similar in boars, gilts and barrows and showed an increasing trend during the study, starting from about 15 g/min up to four times the amount. Immunocastration affected feed intake behavior severely, especially the meal size increased dramatically because of higher feed intake rate, which exceeded that of all other groups by 25% at the end of the study. The number of meals/day was not influenced by immunocastration and was almost identical to that of boars. Highest skatole concentrations were measured in fat of boars, whereas indole concentrations were higher in immunocastrates than in all other groups. In gilts and barrows, skatole concentrations were related to growth rate. Additionally, the feeding rate was an important factor explaining the variability in skatole/indole concentrations in adipose tissue. The physiological mechanisms however need further clarification.     

Gonadal sperm reserve in purebred Landrace and Large White boars of high average daily gain

The present study investigated the effects of average growth rate (AGR) levels and age on the number of sperm cells per gram of testis parenchyma and on the gonadal reserve in Landrace (LD) and Large White (LW) boars. In Experiment 1, the effects of breed (LD, LW), level of AGR from birth up to 90 days of age (Level 1: 384 +/- 32 g/day; Level 2: 512 +/- 22 g/day; Level 3: 624 +/- 41 g/day), and age (13, 15, 17, 19 and 21 weeks) on testicular cell concentration were evaluated. Data were analyzed under a 2 x 3 x 4 factorial design. There were significant effects associated with breed (P < 0.001) and age (P < 0.001) but not with AGR (P > 0.05) on sperm cell number per gram of testicular parenchyma. The number of cells increased with age and was greater in LW than in LD young boars, mainly those up to 19 weeks of age. In Experiment 2, the effect of two AGR levels (Level 1: 649-694 g/day; Level 2: 813-885 g/day) from birth up to 100 kg body weight on the number of sperm cells per gram of testis parenchyma and on the gonadal reserve was investigated using 59 purebred LD and LW boars. The boars were castrated at 23, 25, 29 and 33 weeks of age. Age of boars significantly affected gonadal sperm reserve and the number of sperm cells per gram of testicular tissue (P < 0.001). Breed of boars and AGR Levels did not significantly affect number of sperm cells and gonadal sperm reserve (P > 0.05). It was concluded that the number of sperm cells in the testicular tissue of young boars is influenced by their breed and age, but not by the level of their AGR.     

Multiple trait model combining random regressions for daily feed intake with single measured performance traits of growing pigs

A random regression model for daily feed intake and a conventional multiple trait animal model for the four traits average daily gain on test (ADG), feed conversion ratio (FCR), carcass lean content and meat quality index were combined to analyse data from 1 449 castrated male Large White pigs performance tested in two French central testing stations in 1997. Group housed pigs fed ad libitum with electronic feed dispensers were tested from 35 to 100 kg live body weight. A quadratic polynomial in days on test was used as a regression function for weekly means of daily feed intake and to escribe its residual variance. The same fixed (batch) and random (additive genetic, pen and individual permanent environmental) effects were used for regression coefficients of feed intake and single measured traits. Variance components were estimated by means of a Bayesian analysis using Gibbs sampling. Four Gibbs chains were run for 550 000 rounds each, from which 50 000 rounds were discarded from the burn-in period. Estimates of posterior means of covariance matrices were calculated from the remaining two million samples. Low heritabilities of linear and quadratic regression coefficients and their unfavourable genetic correlations with other performance traits reveal that altering the shape of the feed intake curve by direct or indirect selection is difficult.     

Genetic parameters for feed intake,litter weight,body condition and rebreeding success in primiparous Norwegian Landrace sows

The aim of this study was to estimate genetic parameters for feed intake recorded as farmers’ perception of young sows’ appetite for the first 3 weeks of lactation (APP) and feed intake recorded for one day in the 3rd week of lactation (FEED), litter weight (LW) at 3 weeks, sow body condition at weaning (BC) and the following five reproduction traits: weaning-to-service interval of 1 to 7 days (WSI7), weaning-to-service interval of 1 to 50 days (WSI50), delayed service or not (DELAYED), pregnant on first service or not (PREGNANT) and litter size in 2nd parity (NBT2). The analyses included data on 4606 Norwegian Landrace 1st-parity sows and their litters. The Gibbs sampling method was used. The traits DELAYED and PREGNANT were analysed as threshold traits and APP, FEED, LW, BC, WSI7, WSI50 and NBT2 were analysed as linear traits. The heritability estimates for APP and FEED were low (<0.1), whereas the estimates for DELAYED and PREGNANT were rather high (0.4 and 0.3). The heritability estimate for BC was 0.2. The genetic correlations confirmed the complexity of breeding for sow performance; selection for heavy 1st litters may lead to lower body condition at weaning, which in turn leads to lower reproductive performance and smaller litters in 2nd parity. Selection for higher sow feed intake would improve body condition, but the simple way of measuring feed intake tested in this study (APP and FEED) cannot be recommended because of the low heritability obtained for these traits.     

Simultaneous estimation of daily weight and feed intake curves for growing pigs by random regression

In this study, random regression models were used to estimate covariance functions between feed intake and BW in boars from the two breeds: the Norwegian Landrace and the Norwegian Duroc. In total, 1476 animals of the Norwegian Landrace breed and 1300 animals of the Norwegian Duroc breed had registrations on daily feed intake and growth from 54 to 180 days of age. Random regressions on the Legendre polynomials of age were used to describe genetic and permanent environmental curves in BW (up to the second order) and feed intake (up to the first order) for both the breeds. Heritabilities on BW increased over time for the Landrace (0.18 to 0.24), but were approximately constant for the Duroc (0.33 to 0.35). Average heritabilities for feed intake were approximately the same in both the breeds (0.09 to 0.11), and the estimates decreased over time, most pronounced in Duroc. On the basis of the current data, daily feed intake was seemingly controlled by the same genetic factors throughout the test period for Duroc; however, for Landrace, genetic correlations between test days decreased with increasing distance in time. For BW, the genetic correlations between test days were in general high, and did not go below 0.8 for any of the two breeds in this study. For both feed intake and BW, permanent environmental correlations between start and end of the test were reduced with increasing difference in days, most pronounced in Duroc. This study indicates that weight of the animal at the end of the test was more closely genetically correlated to feed intake of earlier periods compared with later periods of growth for both the breeds. This may be explained by the fact that BW is the cumulative growth of an individual, which is likely to be heavily affected by the feed intake during the most intense growth period.     

Recording strategies and selection potential of feed intake measured using the X-ray method in rainbow trout

This study examines the way long-term feed intake should be recorded accurately for selective breeding purposes, and estimates selection potential in feed intake using the X-ray method to record individual daily feed intake in rainbow trout (Oncorhynchus mykiss). The analysis showed that the point estimates of daily feed intake displayed low repeatabilities (r = 0.09–0.32). This indicates that a minimum of three repeated records were needed to accurately record average feed intake at a fixed age. To effectively breed for feed intake over the whole growing period, it is necessary to determine average feed intake at different ages, since there were only moderate phenotypic and genetic correlations between average daily feed intake recorded at 140 g, 750 g and 2000 g wet mass. Heritability for average daily feed intake was low (average h² = 0.10), indicating that modest genetic changes can be obtained in response to selection. It was concluded that selection to genetically change long-term feed intake can be successful, yet repeated observations at several life stages are needed to ensure the accuracy of feed intake estimates and the efficiency of selection.     

Nutritional restriction of pre-pubertal liveweight gain impairs ovarian follicle growth and oocyte developmental competence of replacement gilts

The objective was to investigate the effects of moderate restriction of pre- and peri-pubertal liveweight gain on ovarian development and oocyte meiotic competence. At 70 d of age, and 27.7 ± 0.4 kg liveweight (LW), 64 Large White/Landrace crossbred gilts were allocated to two treatment groups (n = 32 gilts/treatment); one group was fed to attain a LW of 70 kg at 161 d of age (LIGHT), while the other group was fed to reach 100 kg LW (HEAVY). At 161 d of age, half of the gilts in each group (n = 16) were fed to gain LW at 0.5 kg/d (LOW), while the remaining half (n = 16) were fed to gain LW at 1.0 kg/d (HIGH) between 161 and 175 d of age, at which point they were killed and ovaries collected. For each gilt, surface antral follicles were counted and aspirated according to three size categories: 1-2.9 mm (small); 3-6 mm (medium); and > 6 mm (large). Follicles were pooled for each size class and treatment. Cumulus-oocyte-complexes (COC) recovered from small and medium follicles were matured in vitro (IVM) for 44 to 46 h, and meiotic maturation assessed. There was an effect of treatment (LIGHT versus HEAVY) on the number of medium sized follicles: 25.1 ± 2.59 versus 34.3 ± 2.60 (P < 0.05). The ovaries of LOW gilts had more small follicles and fewer medium follicles compared to those of HIGH gilts: 92.8 ± 8.35 versus 59.8 ± 5.24, and 25.1 ± 2.59 versus 32.5 ± 2.86 (P < 0.05). Target LW at 161 d did not affect meiotic progression of oocytes. However, LOW compared to HIGH LW gain between 161 and 175 d resulted in fewer oocytes reaching MII (0.40 versus 0.54; P < 0.05). In conclusion, moderately restricting feed intake impaired follicle growth beyond 3 mm and reduced oocyte meiotic competence. Further, although a carry-over effect of long-term feed restriction on follicle growth was evident, acute changes in feed intake during the 14 d prior to ovary collection had the greatest effect on oocyte nuclear maturation in vitro.     

Effect of incorporating sugar beet pulp in the finisher diet on performance of geese

The aim of this work was to study the effects of incorporating sugar beet pulp (SBP) into the diet on the development of the crop and performance of geese. A total of 480 1-day-old ganders were divided into three groups differing in the composition and mode of distribution of the diet offered from day 56 to 89. The following two diets were used: a standard diet (nitrogen-corrected apparent metabolizable energy, AME_n 11.44 MJ/kg; 160 g/kg CP) or a diet containing 10% of SBP (SBP diet; AME_n 11.47 MJ/kg; 160 g/kg CP). The swelling capacity (SC) hydration was higher for SBP than for the standard diet (3.62 v. 2.72 ml of H₂O/g of dry matter at 60 min; P<0.05). In the Control group, birds were fed with a controlled time of access to a standard diet. Other birds were fed the SBP diet with a controlled time of access (SBPt group) or a controlled quantity offered (SBPq). From day 90 to 104, 88 birds/group were overfed with a mixture containing mainly corn. Body traits including volume of the crop were measured at day 89. Fatty liver weight and commercial grading were measured at d 104. Feed intake from day 56 to 89 was higher in the Control group than in the SBPt group (8097 v. 7545 g; P<0.05), feed intake in the SBPq group being intermediate (7801 g); however, live weights (LW) of the birds were similar in the three groups measured at day 89 (5746 g; P>0.05). At day 89, the volume of the crop tended to be higher in the SBPt compared with the Control group (52.8 v. 48.8 ml/kg of LW; P=0.101). After overfeeding, feed intake (12 922 g), weight gain (2412 g), LW (8170 g), fatty liver weight (875 g) and commercial grading of the fatty liver were similar (P>0.1) for all the three groups. Therefore, SBP could help adapt the digestive tract of waterfowl to high feed intake through an increase in the crop volume, but its method of use – that is, level of incorporation and mode of distribution – should continue to be investigated.     

Impact of amino acid and CP restriction from 20 to 140 kg BW on performance and dynamics in empty body protein and lipid deposition of entire male,castrated and female pigs

Breeding leaner pigs during the last decades may have changed pig’s empty body (EB) composition, a key trait for elaborating feeding recommendations. This research aimed to provide new experimental data on changes in the chemical composition of the EB of pigs from 20 to 140 kg BW. In addition, the impact of a reduction in the dietary CP associated with lower lysine, methionine+cystine, threonine and tryptophan levels was determined. In total, 48 males, castrates and females weighing 20 kg BW were allocated either to a control grower–finisher diet formulated according to current Swiss feeding recommendations, or a low CP grower–finisher diet (80% of control). Feed intake was monitored and pigs were weighed weekly. The chemical composition of EB (blood, hairs and hoofs, offals, bile, carcass) was determined at 20, 40, 60, 80, 100, 120 and 140 kg BW on four pigs per gender and diet (eight pigs per gender at 20 kg). The five fractions were weighed and samples were analysed for dry matter, protein, fat and energy. Nutrient deposition rates and N efficiency were calculated by using the 20 kg BW category as reference. Analysis revealed an accurate feed optimisation for the aforementioned essential amino acids (EAA), whereas digestible isoleucine content in the low CP diet was at 70% of the control diet. Despite similar feed intake, daily gain and feed efficiency were impaired (P<0.01) from 20 to 100 kg BW in the low CP compared with the control pigs. In the same growth period, castrates had the greatest feed intake but, together with females, displayed the lowest (P<0.01) feed efficiency. Protein deposition was reduced (P<0.01) by up to 31% with low CP diet and was lower (P<0.01) in castrates and females than males at 100 kg BW. The greatest fat deposition rates were found with low CP diet and castrates. N efficiency improved (P<0.05) by 10% with the low CP diet from 100 to 140 kg. The males displayed the greatest (P<0.05) N efficiency. These findings suggest that the CP content of finisher II diets could be reduced to 102, 102 and 104 g/kg for females, castrates and males, respectively, without a negative impact on protein deposition or growth. It remains unclear whether the negative effects found in the BW range from 20 to 100 kg on the EB deposition were due to the 20% reduction of the dietary CP and the five limiting EAA or to other EAA via an unbalanced EAA profile.     

Sire and liveweight affect feed intake and methane emissions of sheep confined in respiration chambers

Daily methane production and feed intake were measured on 160 adult ewes, which were the progeny of 20 sires and 3 sire types (Merino, dual-purpose and terminal) from a genetically diverse flock. All animals were housed in individual pens and fed a 50/50 mix of chaffed lucerne and oaten hays at 20 g/kg liveweight (LW), with feed refusals measured for at least 10 days before the first of three 22-h measurements in respiration chambers (RC). Feed was withdrawn at 1600 h on the day before each RC test to encourage the ewes to eat the entire ration provided for them in the RC. After the first 1-day RC test, the sheep were returned to their pens for a day, then given a second 1-day RC test, followed by another day in their pens, then a third RC test. After all animals had been tested, they were ranked according to methane emissions adjusted for feed intake in the RC and on the previous day, enabling 10 low and 10 high methane animals to be chosen for repeat measurement. No variation between sires nor consistent effects of LW on feed eaten (%FE, expressed as per cent of feed offered) was evident in the 10 days before the first RC measurement. However, significant differences between sires (equivalent to an estimated heritability of 41%) were identified for %FE during the 2^nd and 3^rd days of RC testing (2 and 4 days after the initial RC test). The analysis of all data showed that methane emissions in the RC were related to feed intake on the day of testing and the two previous days (all P<0.0005). Before correcting for feed intake on previous days, there was some variation between sires in methane yield, equivalent to an estimated heritability of 9%. Correction for feed intake on the 2 previous days halved the residual variation, allowing other effects to be detected, including effects of LW, twins reared as singles, test batch, RC and test-day effects, but estimated sire variation fell to zero. In order to avoid potential biases, statistical models of methane emissions in the RC need to consider potential confounding factors, such as those identified as significant in this study.     

Estimation of social genetic effects on feeding behaviour and production traits in pigs

Pigs are housed in groups during the test period. Social effects between pen mates may affect average daily gain (ADG), backfat thickness (BF), feed conversion rate (FCR), and the feeding behaviour traits of pigs sharing the same pen. The aim of our study was to estimate the genetic parameters of feeding behaviour and production traits with statistical models that include social genetic effects (SGEs). The data contained 3075 Finnish Yorkshire, 3351 Finnish Landrace, and 968 F1-crossbred pigs. Feeding behaviour traits were measured as the number of visits per day (NVD), time spent in feeding per day (TPD), daily feed intake (DFI), time spent in feeding per visit (TPV), feed intake per visit (FPV), and feed intake rate (FR). The test period was divided into five periods of 20 days. The number of pigs per pen varied from 8 to 12. Two model approaches were tested, i.e. a fixed group size model and a variable group size model. For the fixed group size model, eight random pigs per pen were included in the analysis, while all pigs in a pen were included for the variable group size model. The linear mixed-effects model included sex, breed, and herd*year*season as fixed effects and group (batch*pen), litter, the animal itself (direct genetic effect (DGE)), and pen mates (SGEs) as random effects. For feeding behaviour traits, estimates of the total heritable variation (T² ± SE) and classical heritability (h² ± SE, values given in brackets) from the variable group size model (e.g. period 1) were 0.34 ± 0.13 (0.30 ± 0.04) for NVD, 0.41 ± 0.10 (0.37 ± 0.04) for TPD, 0.40 ± 0.15 (0.14 ± 0.03) for DFI, 0.53 ± 0.15 (0.28 ± 0.04) for TPV, 0.66 ± 0.17 (0.28 ± 0.04) for FPV, and 0.29 ± 0.13 (0.22 ± 0.03) for FR. The effect of social interaction was minimal for ADG (T² = 0.29 ± 0.11 and h² = 0.29 ± 0.04), BF (T² = 0.48 ± 0.12 and h² = 0.38 ± 0.07), and FCR (T² = 0.37 ± 0.12 and h² = 0.29 ± 0.04) using the variable group size model. In conclusion, the results indicate that social interactions have a considerable indirect genetic effect on the feeding behaviour and FCR of pigs but not on ADG and BF.     

Performances, meat quality and boar taint of castrates and entire male pigs fed a standard and a raw potato starch-enriched diet

In Europe there is increasing concern about the common practice of surgical castration of piglets without anaesthesia. One possible alternative to completely avoid castration is entire male pig production. Thus, the objective of the study was to compare the growth performance, carcass characteristics, organ weights, meat quality traits, fat score and boar taint compounds in the adipose tissue of group-penned entire male pigs and castrates. Furthermore, the effect of raw potato starch (RPS) fed for 7 days prior to slaughter was determined. Pigs (n = 36) were blocked by BW into 12 blocks (3 littermates/block) and assigned to three experimental groups: surgical castrates (C); entire males (EM); and entire males offered RPS (30 g RPS/100 g diet) for 7 days prior to slaughter (EM+). Pigs had ad libitum access to the feed from 22 to 107 kg, individual feed intake was recorded daily and BW once a week. Entire males grew slower (EM: 771, EM+: 776 v. C: 830 g/day; P < 0.01), consumed less feed (EM: 1.87, EM+: 1.89 v. C: 2.23 kg/day; P < 0.01) and were more efficient (feed conversion ratio: EM: 2.42, EM+: 2.44 v. C: 2.69 kg/kg; P < 0.01) than C. Compared to C, carcass dressing percentage was lower (EM: 79.4, EM+: 79.4 v. C: 81.6%; P < 0.01) and percentage of valuable cuts was higher (EM: 57.3, EM+: 56.5 v. 52.6%; P < 0.01) in entire males. The hearts (EM: 426, EM+: 425 v. C: 378 g), kidneys (EM: 387, EM+: 378 v. C: 311 g), bulbourethral (EM: 200, EM+: 195 v. C: 7 g) and salivary glands (EM: 99, EM+: 94 v. C: 42 g) were heavier (P < 0.001) in entire males than in C. Meat quality traits did not (P > 0.05) differ among experimental groups but the adipose tissue was more unsaturated in entire males than in C as indicated by the higher fat scores (EM: 69.1, EM+: 67.2 v. C: 63.6; P < 0.01). Feeding RPS reduced (P = 0.04) the skatole tissue concentrations (expressed in μg/g lipid) in EM+ (0.22) compared to EM (0.85), whereas androstenone and indole levels were not (P 0.60) affected (EM: 1.7 and 0.10, EM+: 2.0 and 0.09, respectively). Although the current results confirmed the high efficiency of entire males compared to castrates, the observed high androstenone levels represent a major challenge to implement entire males production.     

Hydrolysable tannin-based diet rich in gallotannins has a minimal impact on pig performance but significantly reduces salivary and bulbourethral gland size

Tannins have long been considered ‘anti-nutritional’ factors in monogastric nutrition, shown to reduce feed intake and palatability. However, recent studies revealed that compared with condensed tannins, hydrolysable tannins (HT) appear to have far less impact on growth performance, but may be inhibitory to the total activity of caecal bacteria. This in turn could reduce microbial synthesis of skatole and indole in the hindgut of entire male pigs (EM). Thus, the objective of this study was to determine the impact of a group of dietary HT on growth performance, carcass traits and boar taint compounds of group housed EM. For the study, 36 Swiss Large White boars were assigned within litter to three treatment groups. Boars were offered ad libitum one of three finisher diets supplemented with 0 (C), 15 (T15) or 30 g/kg (T30) of HT from day 105 to 165 of age. Growth performance, carcass characteristics, boar taint compounds in the adipose tissue and cytochrome P450 (CYP) isoenzymes CYP2E1, CYP1A2 and CYP2A19 gene expression in the liver was assessed. Compared with C, feed efficiency but not daily gain and daily feed intake was lower (P<0.05) in T15 and T30 boars. Except for the percentage carcass weight loss during cooling, which tended (P<0.10) to be greater in T30 than C and T15, carcass characteristics were not affected by the diets. In line with the numerically lower androstenone level, bulbourethral and salivary glands of T30 boars were lighter (P<0.05) than of T15 with intermediate values for C. Indole level was lower (P<0.05) in the adipose tissue of T30 than C pigs with intermediate levels in T15. Skatole levels tended (P<0.10) to be lower in T30 and C than T15 pigs. Hepatic gene expression of CYP isoenzymes did not differ between-treatment groups, but was negatively correlated (P<0.05) with androstenone (CYP2E1 and CYP1A2), skatole (CYP2E1, CYP2A) and indole (CYP2A) level. In line with the numerically highest androstenone and skatole concentrations, boar taint odour but not flavour was detected by the panellists in loins from T15 compared with loins from C and T30 boars. These results provide evidence that HT affected metabolism of indolic compounds and androstenone and that they affected the development of accessory sex glands. However, the effects were too small to be detected by sensory evaluation.     

Genetic variability in residual feed intake in rainbow trout clones and testing of indirect selection criteria (Open Access publication)

Little is known about the genetic basis of residual feed intake (RFI) variation in fish, since this trait is highly sensitive to environmental influences, and feed intake of individuals is difficult to measure accurately. The purpose of this work was (i) to assess the genetic variability of RFI estimated by an X-ray technique and (ii) to develop predictive criteria for RFI. Two predictive criteria were tested: loss of body weight during feed deprivation and compensatory growth during re-feeding. Ten heterozygous rainbow trout clones were used. Individual intake and body weight were measured three times at threeweek intervals. Then, individual body weight was recorded after two cycles of a three-week feed deprivation followed by a three-week re-feeding. The ratio of the genetic variance to the phenotypic variance was found high to moderate for growth, feed intake, and RFI (VG/VP = 0.63 ± 0.11, 0.29 ± 0.11, 0.29 ± 0.09, respectively). The index that integrates performances achieved during deprivation and re-feeding periods explained 59% of RFI variations. These results provide a basis for further studies on the origin of RFI differences and show that indirect criteria are good candidates for future selective breeding programs.     

Supplementation of alkali-treated rice straw

Goats were fed rice straw treated with 0,4 or 8% NaOH, dehydrated palm oil mill effluent (POME) at 20 or 30 g/kg liveweight (LW)/day and Leucaena at 5 or 10 g dry matter (DM)/kg LW/day in Experiment 1, and rice straw treated with 4% NaOH or 4% NH₄OH, POME at 30 g/kg LW/day and either Napier grass or Leucaena at 10 g DM/kg LW/day in Experiment 2. Treatment with 4% NaOH promoted the highest intake of rice straw. 10·3 and 12·4 g DM/kg LW/day respectively in Experiments 1 and 2. Feeding Leucaena at 10 g DM/kg LW/day significantly increased total intake (36·0 g DM/kg LW/day) and DM digestibility (59·0%) in Experiment 1, and supported a LW gain of 63 g/day in Experiment 2. It is concluded that diets comprising 25% NaOH-straw, 50% POME and 25% Leucaena permitted dietary nutrients to be used efficiently and maximised the inclusion of by-products.     

Effects of the dietary protein content and the feeding level on protein and energy metabolism in Iberian pigs growing from 50 to 100 kg body weight

Nutritional requirements of the Iberian pig, a slow-growing, obese porcine breed, are not well defined and seem to differ from those of conventional or high-performing pigs. The effects of the dietary protein content and the feeding level on the utilisation of metabolisable energy (ME) and the rates of gain, protein, and fat deposition were studied with 81 Iberian castrates growing from 50 to 100 kg body weight (BW) by using the comparative slaughter technique. The animals were fed 4 diets providing 145, 120, 95, and 70 g ideal crude protein (CP) per kg dry matter (DM), and containing 13.94, 14.29, 14.56, and 14.83 MJ ME per kg DM, respectively. Three levels of feeding were evaluated: 0.60, 0.80, and 0.95 × ad libitum intake. Growth rate increased (linear and quadratic, P < 0.001) as the dietary ideal CP content decreased. It also increased with the feeding level (linear, P < 0.001; quadratic, P < 0.05). Gain:feed and gain:ME intake improved by decreasing the ideal CP content in the diet (linear, P < 0.001 and P < 0.05, respectively; quadratic P < 0.001 for both variables). Increasing the feeding level improved linearly gain:feed and gain:ME intake ( P < 0.001). Protein deposition (PD):ME intake ranged between 1.23 and 1.44 g/MJ, and it showed a tendency to reach the maximum value when the diet providing 95 g ideal CP per kg DM was fed (quadratic, P = 0.078). When this diet was offered at 0.95 × ad libitum, PD reached a maximum value of 71 g/day. This dietary treatment resulted in average values for average daily gain and retained energy (RE) of 854 g/day and 21.4 MJ/day, respectively. The average rate of gain was 19.93 g/MJ increase in ME intake, equivalent to an energy cost of 50.2 kJ ME per g gain, irrespective of the dietary ideal CP content. Also, the overall marginal efficiency of protein deposition (ΔPD:ΔME; g/MJ) was 1.34. Increasing the feeding level led to increases in PD (linear, P <  0.001) and RE (linear, P <  0.001; quadratic, P <  0.01) irrespective of the dietary ideal CP concentrations. Between 50 and 100 kg BW, the chemical composition of 1 kg gain averaged 78, 592, 28.7, and 284 g for CP, fat, ash, and water respectively. The net efficiency of use of ME for growth ( k_g) and the maintenance energy requirements were 0.606 and 396 kJ/kg BW ^0.75 per day, respectively. The results support earlier findings that the genotype has marked effects on protein and energy metabolism of growing pigs and underline important compositional differences of the Iberian pig compared with conventional or modern porcine genotypes.     

The effect of alternative feeding strategies on the feeding motivation of broiler breeder pullets

Due to genetic selection for fast growth and high breast meat yield, commercial strains of broiler chickens and broiler breeders are predisposed to high feed intake; however, feeding broiler breeders ad libitum impairs their health and reproductive performance. Broiler breeders are feed-restricted throughout rearing to maintain health and performance, yet feed restriction results in hunger, feeding frustration and lack of satiety. The objective of this study was to examine the effect of alternative feeding strategies, including feed additives (separately or combined) and a fixed non-daily feeding schedule, on the feeding motivation and welfare of broiler breeders during rearing. At 3 weeks of age, 180 Ross 308 breeder pullets were allocated to 90 cages and fed with one of five isocaloric treatments: (1) daily control diet (control), (2) daily calcium propionate diet (CaP), (3) daily soybean hull diet (SBH), (4) daily alternative diet (alternative: CaP + SBH) and (5) 4/3 control diet (four on-feed days and three non-consecutive off-feed days per week). The CaP diet included calcium propionate at 1.4% from 3 to 6 weeks of age, and at 3.2% from 7 to 12 weeks of age, and the SBH diet contained soybean hulls included at 40%. The alternative diet included both soybean hulls and calcium propionate at the same inclusion rate as the SBH and CaP diets, respectively. Pullets were weighed and scored for feather coverage every week. A feed intake test was conducted at 3, 4, 8, 10 and 11 weeks of age for 10 min during on- and off-feed days. At 12 weeks of age, feather samples were analysed for fault bars. Data were analysed using linear mixed regression models, with cage nested in the models and age as a repeated measure. At 4 weeks of age, pullets fed soybean hull-enriched diets (SBH and alternative diets) and those on the 4/3 schedule had lower feed intake than control pullets (P = 0.02). Feathers from pullets fed the SBH diet had fewer fault bars than those fed the CaP diet (P = 0.04). The results indicated that the inclusion of soybean hulls (alone or combined with calcium propionate) and a 4/3 feeding schedule can reduce feeding motivation of broiler breeders during early rearing.     

Differences in productive robustness in rabbits selected for reproductive longevity or litter size

The aim of this work was to evaluate the ability of a line selected for reproductive longevity (LP) to confront productive challenges compared to a line selected during 31 generations for litter size at weaning (V). A total of 133 reproductive rabbit does were used (72 and 61 from LP and V lines, respectively). Within each line, three groups with different levels of productive effort were planned: PP9, inseminated at day 4 after the first partum and with nine kits during the second partum, and inseminated after first weaning (30 days) and with nine (PW9) or five kits (PW5) during the second partum. The reproductive performance, body condition (perirrenal fat thickness (PFT)) and lipolytic response were controlled. LP does showed greater mean live weight (LW; +128 g; P < 0.05), PFT (+0.47 mm; P < 0.05) and estimated body energy (EBE; +0.29 MJ/kg; P < 0.01) than V does at second partum. However, LP does that mated at first post partum did not significantly differ in EBE relative to V does at second partum. During the first week of lactation, dry matter (DM) intake was similar for both lines (94 and 95 g DM/kg LW0.75 day for V and LP does, respectively). There was a significant difference in milk yield between both lines during the first week when litter size was nine (60 v. 54 g of milk/kg LW0.75 day for LP and V does, respectively; P < 0.01), but no difference when litter size was five. Consequently, when litter size was nine, LP does showed a lower recovery of PFT (0.6 mm less; P < 0.05) than V does during the first 10 days of lactation. However, when litter size was five, LP does showed a higher LW (+210 g; P < 0.05) than V does at 10 days of lactation and a similar recovery of PFT. During the last 3 weeks of the lactation, LP does showed a higher feed intake (+6 g DM/kg LW0.75 day; P < 0.05) and milk yield (+27 g/day; P < 0.001) than V does when litter size was nine, resulting in no significant differences in LW at 30 days of lactation. However, when litter size was five, both lines showed similar feed intake and milk yield, maintaining their differences in LW at 30 days of lactation (+206 g for LP does; P < 0.05). These results show that the rabbit line selected for reproductive longevity is more robust with respect to coping with productive challenges, than a line selected for reproductive intensity.