Effect of divergent selection for weaning weight on liveweight and wool growth responses to feed intake in Merino ewes

1993 ◽  
Vol 33 (6) ◽  
pp. 699 ◽  
Author(s):  
RM Herd ◽  
VH Oddy ◽  
GJ Lee
Keyword(s):  
Organic Matter ◽  
Feed Intake ◽  
Divergent Selection ◽  
Growth Responses ◽  
Weaning Weight ◽  
Wool Growth ◽  
Digestible Organic Matter ◽  
Selection For ◽  
Response To Change

During a 6-week experiment, the feed requirements for maintenance of liveweight (LW) by adult Merino ewes were measured in 2 flocks selected over 32 years for divergent weaning weight. Also examined were the net efficiency of LW gain and wool growth in response to change in feed intake, and the ability to digest dietary organic matter. Ewes selected for high weaning weight (W+) were 31% heavier than those selected for low weaning weight (W-) at the start of the experiment. To maintain LW, W+ ewes ate 24% more digestible organic matter (DOM) per day than W- ewes. There were no differences (P>0.2) in the net efficiency of feed use for LW gain. The W+ ewes digested more (P<0.01) dietary organic matter, by 1.8 percentage units, than W- ewes and, consequently, required only 22% more dry feed to maintain their heavier LW. Ewes from the 2 flocks did not differ (P>0.4) in the amount of wool grown, and as W+ ewes were larger, they produced less (P<0.01) wool per kg LW for the same DOM intake.

Stimulation of wool growth by thyroxine implantation. II. Feed intake of grazing Merino wethers treated repeatedly with thyroxine.

1964 ◽  
Vol 15 (4) ◽  
pp. 676 ◽  
Author(s):  
LJ Lambourne
Keyword(s):  
Organic Matter ◽  
Feed Intake ◽  
Sheep Grazing ◽  
Wool Production ◽  
Wool Growth ◽  
Digestible Organic Matter ◽  
The Difference ◽  
Maintenance Requirements ◽  
Substantial Rise ◽  
Stimulation Of

Estimates have been made of the feed intake of wethers that received implantations of 60 mg thyroxine every 3 months, and of untreated sheep, grazing together. The estimated intake of digestible organic matter (D.O.M.) by treated wethers was higher than that of controls in 24 out of 27 measurement periods. The difference in feed intake was least in the iirst month after implantation, when the treated sheep lost weight, and greatest in the second and third months when the treated sheep were regaining weight. The overall increase in intake resulting from thyroxine treatment (20–25%) was greater than the increase in wool production (7% greasy weight, 3-7 % clean weight), and the efficiency of wool production was therefore lower in thyroxinetreated wethers. From the relationships between feed intake and rate of weight change it was concluded that in the month after implantation, when pulse rates indicated a substantial rise in metabolic rate, the maintenance feed requirement was raised from about 560 g to about 780 g D.O.M. per day. Observations in two winters with recently shorn sheep gave estimates of maintenance requirements for untreated wethers ranging from 850 to 1300 g D.O.M. per day. During recovery from repeated thyroxine implantation the wethers gained in weight no more efficiently than the controls. The mechanism of action of exogenous thyroxine is discussed in the light of these and other data.

Selection for weaning weight in Merino sheep. 3. Maintenance requirements and the efficiency of conversion of feed to wool in mature ewes

1967 ◽  
Vol 7 (25) ◽  
pp. 117 ◽  
Author(s):  
WA Pattie ◽  
AJ Williams
Keyword(s):  
Body Weight ◽  
Feed Intake ◽  
Weaning Weight ◽  
Gross Efficiency ◽  
Wool Growth ◽  
Body Weights ◽  
Unit Body Weight ◽  
Selection For ◽  
Feed Costs ◽  
Maintenance Requirements

Net and gross efficiencies of wool growth have been estimated for ewes from three Trangie selection flocks, one selected for high weaning weight (Weight Plus), one for low weaning weight (Weight Minus), and a random control flock. Weight Plus ewes had 15 and 11 per cent heavier body weights than Weight Minus ewes at maintenance and unlimited levels of feeding respectively. At each level, feed intake was proportional to body weight both between and within flocks. In addition, the feed costs of a unit gain and loss of body weight were the same for each flock at each level of feeding. The Weight Plus ewes grew 7 and 10 per cent more wool than Weight Minus ewes at maintenance and unlimited levels of feeding. Consequently, there was only a small difference between the flocks in efficiency of conversion of feed to wool at maintenance, and there was no difference on unlimited intake. These results indicate that there is no genetic correlation between weaning weight and efficiency of conversion of feed to wool. At the three levels of controlled feeding (543, 725, 902 grams of dry matter a day) there were no differences in gross efficiency of wool growth, either between flocks or between levels within flocks, despite differing changes in body weight. During unlimited feeding, gross efficiency of wool growth was lower than that during controlled feeding. This was due to a reduced response in wool growth, as feed costs per unit body weight change were constant. As both production and feed intake changed in proportion to body weight, it is concluded that attention to weaning weight has little place in a Merino breeding program aimed at increasing wool production. However, selection for high weaning weight may be a useful tool in selecting ewes for crossbreeding because of the associated increases in milk production and lamb growth rate.

230 Effect of divergent selection for residual feed intake on whole body protein turnover in growing gilts fed either adequate or lysine deficient diets

2016 ◽  
Vol 94 (suppl_2) ◽  
pp. 108-109 ◽  
Author(s):  
D. J. Hewitt ◽  
C. F. M. de Lange ◽  
T. Antonick ◽  
J. C. M. Dekkers ◽  
A. R. Pendleton ◽  
...  
Keyword(s):  
Feed Intake ◽  
Protein Turnover ◽  
Residual Feed Intake ◽  
Divergent Selection ◽  
Whole Body ◽  
Body Protein ◽  
Selection For

Effects of shelter, exposure and level of feeding over winter on the productivity of Welsh Mountain ewes and lambs

1973 ◽  
Vol 17 (1) ◽  
pp. 21-32 ◽  
Author(s):  
W. I. Robinson ◽  
W. Brown ◽  
I. A. M. Lucas
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Organic Matter ◽  
Live Weight ◽  
Outdoor Exposure ◽  
Wool Growth ◽  
Digestible Organic Matter ◽  
Maintain Body Weight ◽  
Fourth Experiment ◽  
Different Levels

SUMMARYPregnant Welsh Mountain ewes were kept over winter on a hill. All were penned individually, either in a shed or out of doors. In Experiments 1 and 2 different levels of digestible organic matter (DOM) were given in each environment and in Experiment 3 only a single level was offered. In Experiment 2 all ewes were grazed together after lambing; in Experiment 3 some from each treatment were moved to a shed after lambing and their milk yields recorded between 10 and 15 days later.In a fourth experiment on low land, pregnant ewes were either housed or kept in an exposed or a sheltered paddock. All were grazed together after lambing.The results indicated that the requirement of indoors penned sheep to maintain body weight and produce a single lamb is 9·5 g DOM/kg live weight per 24 hr at 16 weeks pre-partum, rising to 15·0 g DOM/kg live weight per 24 hr at 1 week pre-partum. A 10% weight loss during pregnancy would be expected in ewes receiving 75 to 80 % of these requirements. Low intakes during pregnancy reduced wool growth and lamb birth weights.Outdoor exposure reduced pre-partum ewe weight by about 1·5 kg, and so was equivalent to a 10% reduction in daily DOM intake. The magnitude of this effect was not changed significantly by level of feeding. Exposure did not affect wool growth and its influence on lamb birth weight and growth was variable.

scholarly journals The Relation Between the Responses of Wool Growth and Body Weight to Changes in Feed Intake

1962 ◽  
Vol 15 (4) ◽  
pp. 720 ◽  
Author(s):  
KA Ferguson
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Feed Intake ◽  
Weight Change ◽  
Productive Efficiency ◽  
Intake Rate ◽  
Body Weight Change ◽  
Growth Responses ◽  
Wool Growth

The wool growth responses to changes in feed intake are related to the changes produced in body weight. The relation is expressed by the equation W = Ei-kG, where W = wool growth rate, i = feed intake rate, G = rate of body weight change, and E and k are constants. The ratio of E to k in sheep of different productive efficiency was found to be constant.

Effects of duration of introductory feeding and barley content of pelleted diets on the feed intake and liveweight of export sheep

1989 ◽  
Vol 29 (2) ◽  
pp. 169 ◽  
Author(s):  
MH Round
Keyword(s):  
Organic Matter ◽  
Feed Intake ◽  
Digestible Organic Matter ◽  
Ad Libitum

The liveweights and feed intakes of 409 adult wethers, from 2 pastoral sources, were measured in an experiment that simulated the assembly and shipping stages of the export of live sheep. The sheep were held separately with 17 wethers per group, and were introduced in outdoor yards to pelleted diets containing 0, 25 or 50% barley for either 5 or 9 days (adaptation) during which time lucerne hay or oaten hay were also fed. The wethers were then housed in intensive indoor pens (0.33 m21wether) for 14 days and fed the pelleted diets ad libitum without hay. During indoor feeding, wethers fed pellets containing 50% barley ate less pellets than did other sheep (1127 v. 1376 g DM/day, s.e.m. = 25.2, P<0.001). They had similar intakes of digestible organic matter (DOM) (732 v. 757 g/day, s.e.m. = 15.6), but lost more liveweight than did other sheep (- 1.88 v. -0.54 kg, s.e.m. = 0.200, P< 0.001). Increasing adaptation from 5 to 9 days significantly reduced the liveweight loss of wethers fed the diets containing 0% (-1.22 v. -0.20 kg, s.e.m. =0.283, P<0.05) and 25% barley (-1.35 v. 0.63 kg, s.e.m. = 0.283, P< 0.001) but had no effect on wethers fed diets containing 50% barley. Wethers fed lucerne hay during adaptation lost less liveweight indoors than wethers fed oaten hay (-0.66 v. -1.31 kg, s.e.m. = 0.163, P<0.01). Wethers fed lucerne for 9 days tended (P< 0.06) to eat more pellets indoors than other sheep (1386 v. 1262 kg, s.e.m. = 17.9). The wethers had an estimated intake of 37.9 g digestible organic matter/kg0.75 liveweight, which greatly exceeded expected requirements for maintenance and may be partly due to stress associated with intensive housing of the wethers.

Lablab (Lablab purpureus) and lupin (Lupinus angustifolius) seeds as supplements for sheep fed low quality roughage

1998 ◽  
Vol 38 (1) ◽  
pp. 23
Author(s):  
R. M. Dixon ◽  
E. S. Garcia ◽  
J. A. Domingo ◽  
J. H. G. Holmes
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
Nutritional Value ◽  
Synthetic Fibre ◽  
Rumen Fluid ◽  
Lupinus Angustifolius ◽  
Lablab Purpureus ◽  
Wool Growth ◽  
Digestible Organic Matter ◽  
Ad Libitum

Summary. The seeds of lablab (Lablab purpureus) and lupin (Lupinus angustifolius) were investigated as supplements for young sheep. In experiment 1, rumen-cannulated sheep were offered low quality roughage ad libitum alone or supplemented with about 5, 10 or 20 g/kg liveweight whole lupin or lablab seed. Rumen ammonia concentrations were increased by each level of both supplements, and the increases were greater with lupins than with lablab. The pH of rumen fluid was decreased by both supplements, particularly when the higher levels were fed. Dry matter of broken seeds of both legume species rapidly disappeared from synthetic fibre bags incubated in the rumen. Roughage dry matter disappearance from synthetic fibre bags decreased (P<0.05) when 20 g/kg liveweight lupins was fed, and this level of both supplements reduced (P<0.05) roughage intake. Total dry matter intake was increased more by lablab than by lupins, but dry matter and organic matter digestibility tended to be increased to a lesser extent by lablab. Overall, digestible organic matter intake and liveweight gain were increased to similar extents by both supplements. Wool growth was lower (P<0.05) with lablab than lupins, particularly at the highest level of supplementation, suggesting that availability of some amino acids was lower with lablab supplement. In experiment 2, rumen-cannulated sheep were fed low quality roughage ad libitum and supplemented with about 10 g/kg liveweight of either lupin or lablab seed. Lectins and protease inhibitors present in the lablab seed disappeared rapidly from synthetic fibre bags incubated in the rumen. In conclusion the nutritional value of lablab seed as a supplement for sheep fed low quality roughage was similar to that of lupin seed for liveweight gain, but was lower for wool growth.

scholarly journals Meat quality and the calpain system of feedlot steers following a single generation of divergent selection for residual feed intake

2001 ◽  
Vol 41 (7) ◽  
pp. 1013 ◽  
Author(s):  
M. B. McDonagh ◽  
R. M. Herd ◽  
E. C. Richardson ◽  
V. H. Oddy ◽  
J. A. Archer ◽  
...  
Keyword(s):  
Feed Intake ◽  
Shear Force ◽  
High Efficiency ◽  
Subcutaneous Fat ◽  
Residual Feed Intake ◽  
Divergent Selection ◽  
Muscle Area ◽  
Eye Muscle ◽  
Single Generation ◽  
Selection For

Residual feed intake (RFI) is calculated as the difference between an animal’s actual feed intake and its expected feed intake based on its size and growth over a specified test period. Following a single generation of divergent selection for postweaning RFI, Angus steers and Angus × Hereford, Angus×Poll Hereford and Angus × Shorthorn crossbred steers born in 1996 and 1997 were fed in a feedlot. Cohorts of steers were slaughtered at the same age and had attained similar (P&gt;0.05) final liveweights: 467 kg for steers selected for low RFI (high efficiency; HE, n = 91) and 459 kg for steers selected for high RFI (low efficiency; LE, n = 98). The HE and LE steers had similar (P>0.05) carcass weight (247 and 244 kg), dressing percentage (53.1 and 53.2&percnt;) and eye-muscle area (58.9 and 60.3 cm 2 ). The HE steers had slightly less subcutaneous fat over the rib than the LE steers (9.2 v. 10.1 mm, P&lt;0.05), and there was a trend towards less fat over the rump of HE steers (11.5 v. 12.1 mm, P = 0.10). For meat samples taken from the M. longissimus dorsi (LD) there were no differences (P>0.05) between the HE and LE steers in content of intramuscular fat (5.4 and 5.3% fresh weight), marbling scores, meat colour and fat colour. There were also no differences (P>0.05) between HE and LE steers in shear force and compression values for samples of LD aged for 1 day (4.6 and 4.6 kg shear force, 1.45 and 1.44 kg compression), or for 14 days (3.8 and 3.5 kg, 1.36 and 1.32 kg). Myofibril fragmentation index (MFI) measures the breakdown of these structural elements which occurs as an initial step in the process of protein degradation and meat tenderisation. MFI was lower (i.e. less fragmentation; P<0.05) in LD samples from HE steers than from LE steers, both in samples aged for 1 day (67.7 v. 72.5 units) and in samples aged for 14 days (87.8 v. 91.1 units). The rate of decline in MFI between 1 and 14 days post slaughter was similar in the LD samples from both lines of steers. There were no differences (P>0.05) between HE and LE steers in the activity of m-calpain and &micro;-calpain in LD immediately after slaughter (HE steers: 1.9 and 2.3 units, LE steers: 1.8 and 2.1 units). The level of calpastatin in LD from the HE steers was 13% higher than in the LD from the LE steers (5.2 and 4.6 units respectively, P<0.05). Rate of myofibril fragmentation was positively correlated (P<0.01) with the ratios of both m-calpain and µ-calpain to calpastatin, but not (P>0.10) with levels of either calpain or calpastatin. A single generation of divergent selection for RFI produced differences in calpastatin and myofibril fragmentation that may, with on-going selection for low RFI, negatively affect meat tenderness.

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