Performance testing of Simmental bulls in Serbia, II: Phenotypic variability of body developmental traits

Abstract

The performance test of Simmental bulls has been carried out in Serbia Since l982. Ever since the test has been carried out in accordance with a recommendation of the EAAP. Data on 371 tested Simmental bulls, born from 1983-1996, and tested from 1983 to 1997, were used in this study with the aim to analyze a phenotypic variability of major linear body measurements: height at withers (HW), circumference of chest (Cir), depth of chest (DC), width of round (WR), width of hip (WH) and body length (BL). Based on the available linear measurements several relative body developmental indices were also calculated. In order to complete analyze on body developmental traits the following indices were obtained: index of body frame was calculated as IBF=(BL/HW)x1OO, index of chest depth was calculated as ICD=(DC/HW)x1OO, index of body compactness was calculated as ICBL=(Cir/BL)x100 index of massiveness was calculated as IM=(Cir/HW)xlO0, and index of body weight was calculated as IBW=(BW/HW)x1OO. All body measurements are characterized by a linear increase during the test as a result of a very intensive growth pattern. Average test-on (120 days of age) and test-off (365 days of age) height at withers (HW), circumference of chest (Cir), depth of chest (DC), width of round (WR), width of hip (WH) and body length (BL) were 99.88±3.49 and 126.00±2.65 cm, 127.42±6.14 and 184.76±5.95 cm, 42.55±2.25 and 60.90±2.15 cm, 32.56±3.01 and 47.63±2.67 cm, 30.26±2.12 and 44.14±1.93, 106.69±5.99 and 147.57±4.65 cm, respectively. It should be noted that the range of body measurements decreased during the test as a result of bulls' compensatory growth. Furthermore, it is interesting to indicate that variability of traits whose importance for beef production increased with age (i.e. width of round or width of hip) is slightly greater than in the rest of body measurements. Average values for test-on and test-off index of body frame (IBF), index of chest depth (ICD), index of body compactness (ICBL), index of massiveness (IM) and index of body weight (IBW) were 106.8±4.44 and 117.13±3.11%, 42.61±1.90 and 48.34±1.45%, 119.59±5.19 and 125.27±4.26%, 127.58±4.86 and 146.65±4.30%, 194.71±21.34 and 409.32±27.05%, respectively. Obtained results confirm that sufficient variability in major body developmental traits in Simmental bulls exist and it can be utilized for genetic improvement of beef traits. To achieve this goal it is necessary to define proper breeding methods in order to improve beef traits and at the same time to maintain milk traits on the achieved level of their phenotypic expression.

Fenotipska varijabilnost osobina telesne razvijenosti kod simentalskih bikova u performans testu analizirana je na osnovu zvaničnih podataka Centra za reprodukciju i veštačko osemenjavanje iz Velike Plane. Za analizu su upotrebljeni podaci o 371 testiranom biku rođenih u periodu 1983-96, odnosno testiranih od 1983. do 1997. Osobine telesne razvijenosti obuhvatale su s jedne strane najvažnije telesne dimenzije (visina grebena, obim grudi, dubina grudi, širina butova, širina kukova i dužina tela), a sa druge indekse telesne razvijenosti (indeks formata, indeks dubine grudi, indeks zbijenosti trupa, indeks masivnosti, kao i indeks telesne mase). Prosečne vrednosti ± standardna devijacija za visinu grebena, obim grudi, dubinu grudi, širinu butova, širinu kukova i dužinu tala na početku i na kraju testa iznosile su: 99.88±3.49 i 126.00±2.65 cm, 127.42±6.14 i 184.76±5.95 cm, 42.55±2.25 i 60.90±2.15 cm, 32.56±3.01 i 47.63±2.67 cm, 30.26±2.12 i 44.14±1.93, 106.69±5.99 i 147.57±4.65 cm, za linearne dimenzije tela redom navedene. Prosečne vrednosti za izračunate indekse telesne razvijenosti merene na početku i na kraju testa iznosile su: za indeks formata 106.8±4.44 i 117.13±3.11%, za indeks dubine grudi 42.61±1.90 i 48.34±1.45%, za indeks zbijenosti trupa 119.59±5.19 i 125.27±4.26%, za indeks masivnosti 127.58±4.86 i 146.65±4.30%, i za indeks telesne mase 194.71±21.34 i 409.32±27.05%.