Direct and correlated responses to selection for post-weaning weight gain on ad libitum or restricted feeding in mice

1982 ◽  
Vol 63 (2) ◽  
pp. 145-150 ◽  
Author(s):  
D. J. S. Hetzel ◽  
F. W. Nicholas
Keyword(s):  
Weight Gain ◽  
Restricted Feeding ◽  
Correlated Responses ◽  
Weaning Weight ◽  
Ad Libitum ◽  
Selection For

Pre-pubertal mammogenesis in the sheep 3. The effects of restricted feeding or daily administration of bovine growth hormone and bromocriptine on mammary growth and morphology

1986 ◽  
Vol 42 (1) ◽  
pp. 53-63 ◽  
Author(s):  
I. D. Johnsson ◽  
I. C. Hart ◽  
A. Turvey
Keyword(s):  
Growth Hormone ◽  
Weight Gain ◽  
Live Weight ◽  
Restricted Feeding ◽  
Fat Pad ◽  
Live Weight Gain ◽  
Parenchymal Tissue ◽  
Mammary Fat Pad ◽  
Ad Libitum ◽  
Plasma Gh

ABSTRACTIn crossbred female lambs reared on a concentrate diet between 8 and 20 weeks of age, a restriction in food intake to 40 g/kg body weight per day decreased live-weight gain (155 g/day) compared with that in control lambs fed ad libitum (284 g/day) and significantly reduced final live weight and the size of the mammary fat pad (P < 0·001). However, restricted lambs at 20 weeks had more total parenchymal deoxyribonucleic acid (DNA; 54·7 v. 47·5 mg) occupying a greater mass of mammary fat pad (17·0 v. 13·2 g) than control lambs (P > 0·10). Restricted feeding had little effect on mean plasma growth hormone (GH) concentrations at 12 and 18 weeks of age, but decreased plasma insulin and prolactin concentrations.In lambs fed ad libitum, daily subcutaneous (s.c.) injections of 0·1 mg bovine pituitary GH per kg live weight between 8 and 20 weeks of age significantly increased daily live-weight gain (347 g/day; P < 0·001) and also increased total mammary parenchymal DNA (71·2 mg; P < 0·10) and the mass of fat pad occupied by parenchymal tissue (20·6 g; P < 0·05), compared with the control treatment. Daily s.c. injection of bromocriptine (1 mg/day) had no effect on either body or mammary growth, but tended to reduce the effects of bovine GH when given in combination. Secretory activity was observed in the parenchymal tissue of the eight lambs receiving bovine GH alone, and also in five control lambs and three lambs receiving bromocriptine alone. Three lambs that had attained puberty by 20 weeks of age had the poorest mammary development of their respective treatment groups.Mammary gland development at 20 weeks of age was significantly correlated across treatment means with plasma GH concentrations estimated at 18 weeks of age (r = 0·95; P < 0·05), but no correlations of similar magnitude were found between individuals within treatments at 20 weeks. Strongest correlations were found among 8-week-old lambs, where mammary parenchymal DNA was positively correlated with mean plasma GH (r = 0·62) and the GH:insulin ratio (r = 0·79) and negatively correlated with the prolactin:GH ratio (r = -0·65).

Selection for lean growth in pigs with a restricted feeding regime

1994 ◽  
Vol 1994 ◽  
pp. 12-12
Author(s):  
M.K. Curran ◽  
N.D. Cameron ◽  
J.C. Kerr
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Restricted Feeding ◽  
Correlated Responses ◽  
Large White ◽  
Daily Food Intake ◽  
Feeding Regime ◽  
Lean Growth ◽  
Daily Food ◽  
Ad Libitum

Divergent selection lines for lean growth on a restricted feeding regime, in Large White and Landrace pigs, were established to complement the lean growth selection lines on ad-libitum feeding. This study estimated the direct and correlated responses after four generations of selection and the corresponding genetic and phenotypic parameters.The selection objective for lean growth on restricted or scale (LGS) feeding was to obtain equal correlated responses in growth rate and carcass lean content, measured in phenotypic s.d. The selection criterion included measurements of growth rate and ultrasonic backfat depth.Large White (LW) and Landrace (LR) boars and gilts were purchased from eight British nucleus herds and boars from national artificial insemination centres in 1982. Homozygous or heterozygous halothane positive pigs were not included in the experiment. The base populations consisted of 31 LW and 19 LR sires and 57 LW and 67 LR dams. Within each population, there were high and low selection lines with a control line, each consisting of 10 boars and 20 gilts, with a generation interval of 13.5 and 12 months for LW and LR pigs. Animals were performance tested in individual pens from 30±3 kg for a period of 84 days and fed a high energy (13.8 MJ DE/kg DM) and high protein (210 g/kg DM crude protein) pelleted ration. Daily food intake was equal to 0.75 g/g of the daily food intake for ad-libitum fed pigs and the total food intake was 134 kg for LW pigs and 150 kg for LR pigs. On average, 3 boars and 3 gilts were tested per litter. The total number of pigs tested per line and average inbreeding coefficients at generation four, by population are given below.

Divergent breeding values for fatness or residual feed intake in Angus cattle. 5. Cow genotype affects feed efficiency and maternal productivity

2018 ◽  
Vol 58 (1) ◽  
pp. 80 ◽  
Author(s):  
M. L. Hebart ◽  
J. M. Accioly ◽  
K. J. Copping ◽  
M. P. B. Deland ◽  
R. M. Herd ◽  
...  
Keyword(s):  
Weight Gain ◽  
Feed Intake ◽  
Feed Efficiency ◽  
Residual Feed Intake ◽  
Bodyweight Gain ◽  
High Fat ◽  
Low Fat ◽  
Weaning Weight ◽  
Angus Cattle ◽  
Selection For

Cow bodyweight gain, calf weaning weight, feed intake and maternal productivity of 500 Angus cows, in 64 replicate groups, were measured over three parities at two locations (Struan and Vasse) as part of the Beef CRC Maternal Productivity Project. The cows were sourced as heifers from the top and bottom 10% of BREEDPLAN Rib Fat EBV (High-Fat and Low-Fat), and from High and Low residual feed intake (RFI) selection lines (High-RFI and Low-RFI). Each of the four genotypes were run under High- and Low-Nutrition (measured as feed on offer) at both sites. The High-Fat cows were 7% more efficient at producing weaner calves under Low-Nutrition than were the Low-Fat cows. This was driven primarily by the 4% difference between the lines in weaning rate. When weaning rate differences were accounted for (as covariate), there was no difference between the Fat lines in the efficiency of weaner weight production. When the weight gain of the cow was included as an output in addition to calf weaning weight, there was also no difference between the Fat lines in efficiency. Low-RFI cows were always more efficient at producing weaner calves than were the High-RFI cows. This was primarily driven through a 7% reduction in annual feed intake (across both nutrition treatments). However, the Low-RFI cows were leaner, had 6.3% lower weaning rate and calved on average 5.4 days later than did the High-RFI cows. Furthermore, the largest differences in feed intake were in spring when feed availability is greatest. In the context of the results herein, a balanced breeding program should include selection for improved reproduction and low RFI.

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