Susanne Stern

Skatole, androstenone and taint in boars fed two different diets

Abstract Skatole, androstenone, boar taint intensity and organoleptic traits were investigated in samples of fat and lean meat from 143 boars, fed either a high or a low nutrient-density diet and slaughtered at 110 kg live weight. Skatole was also analysed in 41 littermate gilts, and was determined with a new automated Danish method employing spectrophotometry. Seven fat samples, all from boars, exceeded a threshold value for skatole of 0.20 ppm. Of these, 5 came from boars fed the low nutrient-density diet. Skatole was quite strongly correlated with panel-determined boar taint in fat ( r =0.65), as well as with the scores for taint, overall taste and bitter taste of lean meat ( r =0.68, 0.56 and 0.45, respectively). A somewhat lower correlation was obtained between androstenone and boar taint in fat ( r =0.53), and especially between androstenone and the lean meat variables ( r =0.20, 0.28 and 0.25, respectively). The correlation between skatole and androstenone was 0.32. It is concluded that the fat-soluble substance androstenone is a reasonably good predictor of boar taint presence in backfat. Skatole, which is both fat-and water-soluble, appears to be a good determinant not only for boar taint in fat, but also for the taste of lean meat.

Osteochondrosis and leg weakness in pigs selected for lean tissue growth rate

Abstract This study was based on Swedish Yorkshire pigs from two lines in a selection experiment. Selection was performed in four generations for high lean tissue growth rate (LTGR) on a low protein (LP, 13.1% crude protein (CP)) or a high protein (HP, 18.5% CP) diet. In total, 2817 pigs were scored for leg weakness (LWS), LTGR, lean percentage and growth rate. After being performance tested 1470 of the non-selected pigs were slaughtered. Osteochondrotic (OC) changes in their elbow and knee joints were then scored, and lean percentage was estimated by partial dissection. The LP-line had a significantly better constitution, regarding both LWS and OC-scores, than the HP-line. Females had better OC-scores than males. Genetic parameters were estimated with REML using a multiple-trait animal model. The heritabilities estimated were 0.1–0.2 for LWS and 0.2–0.5 for OC. LTGR showed a weak but favourable genetic correlation with osteochondrosis in the knee in both lines. LWS did not show any genetic correlation with LTGR in the LP-line, but showed an unfavourable genetic correlation (−0.50) with LTGR in the HP-line. A significant unfavourable genetic trend was found for LWS in the HP-line. Lean percentage was unfavourably correlated genetically with LWS and OC-scores for the elbow. Genetic correlations between LWS and OC-scores were in the expected direction.

Skatole levels in pigs selected for high lean tissue growth rate on different dietary protein levels

Skatole content in backfat was studied in purebred Yorkshire pigs, selected for lean tissue growth rate on either a low-protein diet containing yellow peas, or a conventional high-protein diet. The present study included 162 entire males and 91 females from generations 1, 2 and 4 in the selection experiment. The animals were slaughtered at approximately 103 kg live weight. Entire male pigs from the low-protein line had on average higher skatole levels than males fed the high-protein diet or females fed either diet (P ≤ 0.001). No difference was found between the sexes from the high-protein line. Only 2.8% of males in the high-protein line exceeded the threshold value suggested for skatole (≥ 0.20 ppm), which should be compared with 23.3% of the males in the low-protein line. In one replicate of the low-protein line as many as 10 out of 20 of the male pigs exceeded the threshold value. These 10 male pigs were half- or full-sib progeny of two sires that were half-brothers. The difference in skatole level between male pigs from the two selection lines might depend on an interaction between feed composition and some genetic influence. The results suggest that the genetic effect for skatole deposition may be due to a recessive gene - probably a major gene - having a pronounced effect especially under certain environmental conditions.

Performance, site preferences, foraging and excretory behaviour in relation to feed allowance of growing pigs on pasture

Foraging behaviour and daily weight gain (DWG) were studied in outdoor pigs given 100 or 80% of the indoor recommended feed allowance. In total, there were four groups of pigs, two per treatment. Each group consisted of 11 growing pigs with an initial live weight (LW) of 50.3 kg. The pigs foraged on a clover/grass pasture for 6 weeks in the cropping season. Behaviour was recorded within three zones of the experimental area: newly allotted area, transfer area and dwelling area. Mean DWG was 811 and 686 g on the 100 and 80% levels, respectively. The feed conversion ratio did not differ between treatments. A higher frequency of rooting and a lower frequency of behaviours categorised as other activities were observed on the 80% level than on the 100% level. Grazing and rooting were more frequent on newly allotted areas compared with the transfer and dwelling areas, whereas passive behaviour and other activities were more frequent in the transfer area. Defecation and urination were most frequent in newly allotted areas, followed by the dwelling area. The results suggest that successive allocation of new land gives rise to a distinct foraging area, which also is frequently used for excretory behaviour. Reducing feed allowance by 20% increased the nutrient intake from the herbage by ∼5%.

A Genetic Study of Pubertal Age, Litter Traits, Weight Loss during Lactation and Relations to Growth and Leanness in Gilts

Abstract Multivariate REML analysis was used to treat the results of a selection experiment for lean tissue growth rate that included 393 purebred Swedish Yorkshire gilts. Heritabilities were estimated to be 0.51, 0.33, 0.45 and 0.41 for pubertal age, litter size, mean piglet birth weight and weight loss during first lactation, respectively. There was a negative genetic correlation between pubertal age and growth rate and a positive one between pubertal age and leanness. The genetic correlation was positive between growth rate and piglet weight and negative between litter size and piglet weight. Age at puberty, litter size and piglet weight showed a positive genetic correlation with weight loss during lactation.

Production Results and Technological Meat Quality for Pigs in Indoor and Outdoor Rearing Systems

The objective of the study was to compare production results and technological meat quality for pigs born outdoors and reared indoors or outdoors during the summer period. A total of 279 pigs was reared in a large pen on deep litter, or outdoors. Daily weight gain and lean meat percentage were higher for pigs outdoors than indoors during year one (864 vs. 841g; 56.9 vs. 55.9%), but were similar for year two (859 vs. 844g; 55.9 vs. 55.6%). Outdoor pigs grew faster when fed ad libitum, but slower during the second phase when restricted, with inferior feed conversion. Most technological meat quality traits (surface and internal reflectance, marbling, pHBF, filter paper wetness, cooking loss and maximal Warner-Bratzler shear force) were similar between rearing systems, whereas pHLD was higher indoors. Total work of Warner-Bratzler shear force was lower in outdoor reared pigs. Maternal sire breed (Duroc or Landrace) and sex (castrate or gilt) did not notably affect meat quality traits. RN genotype had a stronger impact on meat quality than rearing system. It can be concluded from the similarities in production results and meat quality in both systems, that both indoor and outdoor rearing are good alternatives for summer rearing of pigs.

Refined localization of the FAT1 quantitative trait locus on pig chromosome 4 by marker-assisted backcrossing

BackgroundA major QTL for fatness and growth, denoted FAT1, has previously been detected on pig chromosome 4q (SSC4q) using a Large White – wild boar intercross. Progeny that carried the wild boar allele at this locus had higher fat deposition, shorter length of carcass, and reduced growth. The position and the estimated effects of the FAT1 QTL for growth and fatness have been confirmed in a previous study. In order to narrow down the QTL interval we have traced the inheritance of the wild boar allele associated with high fat deposition through six additional backcross generations.ResultsProgeny-testing was used to determine the QTL genotype for 10 backcross sires being heterozygous for different parts of the broad FAT1 region. The statistical analysis revealed that five of the sires were segregating at the QTL, two were negative while the data for three sires were inconclusive. We could confirm the QTL effects on fatness/meat content traits but not for the growth traits implying that growth and fatness are controlled by distinct QTLs on chromosome 4. Two of the segregating sires showed highly significant QTL effects that were as large as previously observed in the F2 generation. The estimates for the remaining three sires, which were all heterozygous for smaller fragments of the actual region, were markedly smaller. With the sample sizes used in the present study we cannot with great confidence determine whether these smaller effects in some sires are due to chance deviations, epistatic interactions or whether FAT1 is composed of two or more QTLs, each one with a smaller phenotypic effect. Under the assumption of a single locus, the critical region for FAT1 has been reduced to a 3.3 cM interval between the RXRG and SDHC loci.ConclusionWe have further characterized the FAT1 QTL on pig chromosome 4 and refined its map position considerably, from a QTL interval of 70 cM to a maximum region of 20 cM and a probable region as small as 3.3 cM. The flanking markers for the small region are RXRG and SDHC and the orthologous region of FAT1 in the human genome is located on HSA1q23.3 and harbors approximately 20 genes. Our strategy to further refine the map position of this major QTL will be i) to type new markers in our pigs that are recombinant in the QTL interval and ii) to perform Identity-By-Descent (IBD) mapping across breeds that have been strongly selected for lean growth.

Two strategies for meeting energy demands of growing pigs at pasture

Abstract In Sweden it is mandatory to keep pigs at pasture between May and September in organic farming. Farmers are recommended to increase feed allowance by 15–20%. We compared two methods for accomplishing the feed energy increment, with regard to pasture intake and total consumption ability. Growing pigs at pasture were given 15% extra metabolizable energy (ME) above indoor recommendations by increasing energy concentration (Conc.) or volume (Vol.) of a standard diet. A total of 54 pigs were included divided on the two treatments and on two replicates. In total, Conc. groups increased their DM intake by 10% (pasture) and ME intake by 19% (13.7 feed and 5.7 pasture) above indoor requirements. Correspondingly, the Vol. groups increased their DM intake by 15% (7.6 feed and 7.6 pasture) and ME intake by 12% (7.6 feed and 4.2 pasture). Daily weight gain (DWG) for Conc. and Vol. treatments was 879 and 912 g ( P =0.109) and the dressing percentage was 77.8 and 75.8 ( P =0.002). Carcass traits were not significantly different. Both Conc. and Vol. pigs grazed at pasture. An increment in ME intake up to 10% can be carried out either by increasing feed volume (amount) or feed ME concentration in addition to grazing. For a further increase, feed ME concentration must be enhanced to avoid limitations in total consumption ability.

Effects of Piglet Weight and Fraternity Size on Performance, Puberty and Farrowing Results

Abstract Effects of fraternity size, birth weight and early growth rate on the pig were studied. 985 gilts were used to study factors affecting performance traits. They were selected for lean tissue growth rate in two different lines, one fed a high protein diet, the other a low protein diet. The puberty analysis comprised 474 gilts. 482 sows with 937 litters were used in the farrowing study. Birth weight was favourably related to growth rate for all the periods measured, and to lean percent as well as high litter weights at farrowing. Fraternity size was unfavourably related to growth rate from birth to 25 kg in both lines and age at puberty in the low protein line. However, fraternity size was favourably related to growth rate from 25–90 kg, and to litter size and litter weight at farrowing. The gilts piglet growth rate was not related to litter size or litter weight at farrowing.

Estimated Mature Weights and Growth Curves for Large White Sows

Mature weight for Large White sows was estimated as the asymptote of a negative exponential growth curve. The data consisted of 2620 weight recordings from 147 sows for the period 1995?1999. Body weight was recorded every 2 weeks from 150 days of age until first service and at parturition and weaning in each parity. A starting point of 150 days was chosen in order to fit the Brody function to the data. Estimates of mature weight in relation to the number of records available (5?10, 11?15, 16?20 and >20) per sow were 285, 258, 260 and 270 kg, respectively. The goodness of fit was calculated as a residual standard deviation (9.7?15.4). No significant effect on mature weight was found for feeding level during rearing or age at first service. The estimated mature weights increased with the number of records available and was more reasonable if the weights were collected throughout the growth and reproductive period.