caa a22 4500 397567456 CHVBK 20180308164831.0 cr unu---uuuuu 161202e199607 xx s 000 0 eng 10.3382/ps.0750828 doi (NATIONALLICENCE)oxford-10.3382/ps.0750828 Selection for High and Low Threshold Body Weight at First Egg in Broiler Strain Females [Elektronische Daten] 7. Effect of Photoperiod on Body Weight and Age at Onset of Mature Semen Production, in Males of The Selection Lines, and in Commercial Broiler and Layer Males [YOAV EITAN, MORRIS SOLLER] Effect of photoperiod on age and BW at attainment of mature semen production was examined in males of lines selected for high (HL) and low (LL) threshold BW at onset of lay, and in males of a commercial Cornish male line (MC), a commercial broiler breeder female line cross (BX), and a commercial layer cross (LX). Photoperiod treatments were: I, increasing natural spring light; and D, steadily decreasing artificial light provided in a light-controlled room. Under I, age at onset of mature semen production was 168.5, 133.6, 138.1, 124.0, and 118.0 d for HL, LL, MC, BX, and LX males, respectively. Under D, age at onset of mature semen production increased by 18.3, 8.0, 55.9, 60.9, and −2.0 d, respectively. The differential effect of Treatment D on the various genetic stocks is attributed to differences between stocks in photoperiodic drive. Therefore, the very great increase in age at onset of mature semen production in BX and MC males points to a severe reduction in photoperiodic drive in males of these stocks, and to future problems in male fertility in broiler breeder flocks entering lay in the summer and fall. Lines HL, LL, BX, and LX rank the same with respect to photoperiodic drive, whether measured in males as in this experiment, or in females, as in a previous experiment. This result suggests that genetic factors affecting photoperiodic drive come to similar expression in males and females. Thus, selection for increased photoperiodic drive in broiler line males may be able to increase photoperiodic drive in broiler line females, and in this way improve female reproductive performance. © 1996 Poultry Science Association, Inc. Breeding and Genetics nationallicence semen production nationallicence photoperiodic drive nationallicence males nationallicence threshold weight nationallicence selection nationallicence EITAN YOAV aut SOLLER MORRIS aut Poultry Science Oxford University Press 75/7(1996-07), 828-832 0032-5791 75:7<828 1996 75 ps https://doi.org/10.3382/ps.0750828 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.3382/ps.0750828 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- EITAN YOAV aut NATIONALLICENCE 700 1- SOLLER MORRIS aut NATIONALLICENCE 773 0- Poultry Science Oxford University Press 75/7(1996-07), 828-832 0032-5791 75:7<828 1996 75 ps Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence SWISSBIB 397065264 BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford