Birgitta Malmfors

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.

Consumer reactions to boar meat - A review

Abstract Over the last ten years, consumer reactions to boar meat have been studied in nine experiments performed in six European countries. In these different studies, conditions have differed with regard to experimental design, proportions of tainted boars and products tested. The proportions of consumers judging the odour of the tested boar meat to be less pleasant than that of normal pig meat has mainly varied from about 5 to 35%. This should be compared with 3–10% for meat tested from gilts and castrates. The results differ between countries and also between products. The most favourable results have been obtained for cured bacon, cooked ham and sausage. The conclusion must be drawn that most boar meat would be accepted by consumers. Further research should be directed to finding a reliable screening test for sorting out tainted boar carcasses.

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.

Incidence of boar taint in Swedish Landrace and Yorkshire boars

Abstract Boar taint in 500 Swedish Landrace and Yorkshire boar carcasses was tested by smelling fat samples heated on the tip of a soldering iron at 150°C. About 40% of the boars were scored as non-tainted; in another 40%, the judges were unsure whether taint was present or not. Boar taint was judged present in only 20% of the boars. The effects of weight and sex on boar taint were studied in approx. 275 boars, barrows and gilts slaughtered at 70, 90, 110 and 130 kg live weight. The number of boars scored as tainted increased with weight, but weight did not affect the level of taint in all boars. When the taste of boar meat and fat was compared to castrates, no differences were found in 80% of comparisons at 70 or 90 kg. The effect of weight on boar taint was studied in 69 boars reared on ad libitum or restricted feed. Biopsies were taken, by a needle biopsy technique, at 70, 90 and 100 kg live weight. The incidence of boar taint did not increase from 70 to 100 kg when boars were on restricted feed, but the weight effect was significant and linear at the ad libitum feeding level. The cause was probably an interaction between physiological development, age and weight of the boars.

Participatory definition of breeding objectives for sheep breeds under pastoral systems—the case of Red Maasai and Dorper sheep in Kenya

Crossing local breeds with exotic breeds may be an option for increased livestock productivity. However, there is a risk for endangerment of the local breeds. One such case is in Kenya where the imported Dorper breed is used for crossbreeding with Red Maasai sheep. The aim of this study was to investigate farmers’ trait preferences as a basis for determination of breeding objectives for Red Maasai and Dorper sheep at two sites, Amboseli and Isinya, in Kenya. Within their own flock, each farmer identified three ewes representing the best, average and poorest within each breed group: Red Maasai, Dorper and Crosses. Farmers gave reasons for their ranking. Body measurements and weights were also taken. At the harshest site, Amboseli, differences between breed groups in body weight were small and breeds were equally preferred. In Isinya, where environmental conditions are better and farmers are more market oriented, Dorper and Crosses had significantly higher body weights and market prices and were thus preferred by the farmers. Red Maasai were preferred for their maternal and adaptive traits. Breeding objectives should emphasize growth traits and milk production in both breeds at both sites. Body condition needs to be specifically considered in the breeding objectives for sheep in Amboseli, whereas adaptive traits need to be generally emphasized in Dorper.