Publikationsdatenbank

Untersuchungen des Haarkleides und der Mast- und Schlachtleistung von Haarschafen und Haarschafkreuzungen (2002)

Art

Hochschulschrift

Autor

Diehl, Manuela Christine

Quelle

Berlin, 2002 — 178 Seiten

Kontakt

Institut für Tierernährung

Königin-Luise-Str. 49
14195 Berlin
+49 30 838 52256
tierernaehrung@vetmed.fu-berlin.de

Abstract / Zusammenfassung

The purpose of the study was to investigate whether the crossing of wool sheep with hair sheep resulted in a sheep type, which combined the advantage of moulting with high fattening performance and improved carcass quality. Age-related and seasonal changes of fleece characteristics were investigated in 8 adult sheep which had been produced by crossing German milksheep x Cameron hairsheep (F!). In addition, hair quality and growth and carcass performance were studied in lambs of the following crossings: Texel x Cameron hairsheep (KI)German milksheep x Cameron hairsheep X Texel x Cameron hairsheep (K2) and pure breed hair sheep (KHS).Each group consisted of 4 female and 4 male lambs.
Fiber samples of different areas of the body were analyzed for their fleece composition (ratio of wool, hair and kemp fibers) as determined by fibre diameter.
The fleece composition of the animals within the investigated group varied, however the changes with season and age were consistent throughout all animals. There are 2 groups of sheep : one type with fibre diameter between 31 and 35 pin and an other one with 40-44 µm. Significant differences in the degree of fines were found between the different body areas (shoulder, 32,2 µm < back, 32,7 pin < hip, 38,3 µm< belly 43,5 pin). Seasonal changes are manifested in changes of the fleece composition, with a eduction of the wool fibers in April and May, the time of seasonal shedding, results in a dominance of hair and kemp fibres in summer through October. Further, during summer a decrease of the average length of the fibers occurs in all areas of the body.In contrast, age-related changes in fibre diameter result in a change of the fiber diameter of all three fiber categories while fleece composition emained the same. Fibre quality in the 3 groups of lambs was analyzed for its changes over the first 5 months after birth.The birth coat varied between the groups. Of the crossed breeding groups, K2 showed a higher degree of woolliness than K1. In both groups, the moulting of hair and kemp fibers was finished at the age of three months, and mainly wool fibers remained. The birth coat of the pure breed hair sheep did not vary significantly from that of the crossed breeding lambs. However, the developmental changes in the hair composition of the pure breed group continued up to an age of 5 months, and mainly consisted of heterotype fibers.The birth weight is significant different between the three groups but there is no difference between the sex (KI: 3,75 kg, K2: 3,25 kg, KHS: 2,65 kg). To determine fattening performance and nutritional requirements, a feeding test was used under standardized conditions. The daily gain in body weight was significant higher in the crosses compared to the pure breed animals.
As a consequence, their growth capacity exceeded that of the pure breed group.
Feed utilization only varied between the sex, there are no differences between the groups. The birth weight of K2 is lower than of KI. Surprisingly, the gap had been eliminated and even reversed by 14 weeks of age.
A comparison between the groups showed significantly heigher weight gains in the crosses than in the hairsheep group. All results showed gender differences. Carcass performance was evaluated using the following parameters Final liveweight, carcassweight, dressing percentage, carcass evaluation, measurement of leg and rack, breast girth, back length, inner body fat weight, weights and proportions of the carcass cut parts, weights and proportions of he dissected tissues (lean, fat and bone), eye muscle area, pH values of 1,5 and 24 h p.m., meat colour, water binding capacity, measurements of femur and cannon bone. As expected, all absolute weights and sizes were higher in crossed groups than in the pure breed animals, and higher in males than in females. The results indicate that the crossed breeding sheep provide an advantage over the pure breed hair sheep.
They combine two economically valuable aspects, carcass of high-quality with seasonal shedding, which eliminates the cost of shearing.