Response to selection of a breeding program for Suffolk sheep in the Czech Republic

Abstract

Lamb growth performance traits in relation to parental breeding values (BVs) for these traits were evaluated in a purebred Suffolk sheep population in the Czech Republic. The research lasted over 8 years and included 24 886 lambs. Four relevant parental BVs were observed: BV predicted for lamb live weight direct effect (BVLW-DE), BV predicted for lamb live weight maternal effect (BVLW-ME), BV predicted for lamb musculus longissimus lumborum et thoracis depth (BV-MLLT), and BV predicted for lamb backfat thickness (BV-BT). The lamb live weight (LW; kg), musculus longissimus lumborum et thoracis depth (MLLT; mm), and backfat thickness (BT; mm) were assessed at 100 days of age. A dataset was created using the most current parental BVs for each year (2007–2014) and subsequent growth traits of their lambs in the next season (2008–2015). Linear regressions showed an increased tendency when one point in dam BVs was associated with an increase in lamb LW (0.393 kg; P < 0.01 in BVLW-DE and 0.090 kg; P < 0.05 in BVLW-ME), MLLT (0.340 mm; P < 0.01 in BV-MLLT), or BT (0.243; P < 0.01 mm in BV-BT). Lower (but significant – P < 0.01) values on linear regression were detected for sire BVs, when 0.135 kg of LW, 0.217 mm of MLLT, and 0.214 mm of BT corresponded to 1-point increases of BVLW-DE, BV-MLLT, or BV-BT. This was confirmed by ANOVA evaluation, especially for LW and MLLT traits. Maximal differences (P < 0.05) in lamb LW were 1.84 kg or 0.88 kg regarding to dam or sire BVLW-DE groups. Similarly, the difference (P < 0.05) in lamb MLLT reached 0.82 mm in dam BV-MLLT, while 0.57 mm was detected in sire BV-MLLT groups. These results have practical implications for the objectives of selection schemes used in the Suffolk sheep population in the Czech Republic.