No abstract

Environmental factors affecting fasting metabolic rate (FMR) were quantified and a short-time recording system was developed. Discontinuous measurements of gas exchange of 1,120 medium weight brown egg layers were taken after 24 and 36 hr of starvation. Body weight (BW) and shank length (SL) were measured and feather cover and activity evaluated by scores. The FMR increased with deterioration of plumage cover. Differences between hens with complete feather cover (Score 1) and nearly naked birds (Score 4) were 8 kJ2/hr at night and 11 kJ/hr during the light phase. Fully fed hens measured during the light phase showed the same curvilinear relationship as starved birds. Only a small proportion of the heat increment generated by ingested food is used by poorly feathered hens to maintain body temperature. Gaseous exchange was affected by locomotor activity in the respiration chamber. The FMR of resting and quietly standing birds were 29.75 +/- 1.00 kJ/hr and 30.55 +/- 1.00 kJ/hr, respectively. During the prelaying phase, FMR showed an increment of 13 kJ/hr with a peak shortly before oviposition. The following exponential relationships between BW in kilograms, and SL in centimeters with FMR were estimated for light phase FMR = 18.52 BW .59 +/- .05 kJ/hr, R2 = .11; for dark phase FMR = 15.21 BW 54 +/- .04 kJ/hr, R2 = .17 and FMR = .32 SL 1.64 +/- .10 kJ/hr, R2 = .19. In poorly feathered strains, SL was as good a predictor of body size as BW. Correcting FMR data for feather loss changed regression coefficients and allometric functions significantly: for light phase FMR = 15.47 BW .74 +/- .03 kJ/hr and R2 = .15; for dark phase FMR = 13.11 BW .66 +/- .03 kJ/hr and R2 = .28.

Inhalt: Bs wird eine neue Translokation heim Schwein beschriehen. Mit Bandmuster analysen wird diese Chromosomenmutation als eine reziproke, autosomale t (1p‐; 16p+) Tranlokation identifiziert. Diese Translokation wird erstmals beschrieben und stellt die erste bekannt gewordene reziproke Translokation bei der Deutschen Landrasse dar.

SUMMARYTwo mouse populations, randombred albino mice and a cross of four inbred strains, were divergently selected for high (H8) and low (L8) 8-week body weight over 18 generations using within-family and individual selection. The crossbreds showed asymmetry of selection response and realized heritabilities (H8 0·29 ± 0·01; L8 0·17 ± 0·01). In the randombred population realized heritabilities were symmetrical (H8 0·23 ± 0·01; L8 0·22 ± 0·02). Over the first nine generations individual selection was nearly 40 per cent better than within-family selection, as was expected from the full sib correlation in both populations. As selection progressed, within-family selection reached 82% and 61% of the responses obtained with individual selection in the crossbreds and randombred respectively. Correlated responses for 3-week (weaning) and 5-week body weights agreed with observations made on direct responses, but selection for L8 did not reduce weaning weight. Selection for L8 decreased and selection for H8 increased first litter size at birth. However, mass-selected L8-pairs had a higher life-reproduction and life-span than H8-pairs.