RESPONSES TO INDEX SELECTION FOR REDUCED BACKFAT THICKNESS AND INCREASED GROWTH RATE IN SWINE

1990 ◽  
Vol 70 (3) ◽  
pp. 973-977 ◽  
Author(s):  
R. M. McKAY
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Average Daily Gain ◽  
Selection Response ◽  
Backfat Thickness ◽  
Index Selection ◽  
Selection Differential ◽  
Differential Selection ◽  
Selection For ◽  
Daily Gain

Selection resulted in a decrease in probed backfat thickness and a negligible change in postweaning average daily gain. Realized heritabilities in the Yorkshire and Hampshire select lines were 0.41 ± 0.04 and 0.34 ± 0.18, respectively, for probed backfat thickness and 0.38 ± 0.43 and 0.65 ± 0.19, respectively, for postweaning average daily gain. Key words: Swine, selection differential, selection response, backfat, growth rate

Effect of index selection for reduced backfat thickness and increased growth rate on sow weight changes through two parities in swine

1992 ◽  
Vol 72 (2) ◽  
pp. 403-408 ◽  
Author(s):  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Selection Pressure ◽  
Backfat Thickness ◽  
Index Selection ◽  
Weight Changes ◽  
Selection For ◽  
The Impact

The impact of continued selection for reduced backfat thickness and improved growth rate on weight changes in Yorkshire and Hampshire sows, from breeding as gilts to weaning their second litter, was studied. Results suggest that some sow weight changes may have been influenced by selection pressure exerted. Key words: Sows, Canadian Yorkshire, Hampshire, liveweight change

Preweaning losses of piglets as a result of index selection for reduced backfat thickness and increased growth rate

1993 ◽  
Vol 73 (2) ◽  
pp. 437-442 ◽  
Author(s):  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Selection Index ◽  
Backfat Thickness ◽  
Index Selection ◽  
Selection For ◽  
Preweaning Period

Index selection for reduced backfat thickness and increased postweaning growth rate resulted in increased preweaning death losses due either directly or indirectly to the sow in the Yorkshire and Hampshire breeds. This resulted in a reduced percentage of piglets weaned in the Yorkshire breed. Key words: Swine, selection index, preweaning period, mortality, survival

scholarly journals The Impact of Selection using Residual Average Daily Gain and Marbling EPDs on Growth Performance and Carcass Traits in Angus Steers

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
T. R. Krause ◽  
E. R. Moore ◽  
J. Duggin ◽  
J. R. Segers ◽  
T. D. Pringle
Keyword(s):  
Growth Performance ◽  
Feed Efficiency ◽  
Average Daily Gain ◽  
Backfat Thickness ◽  
Feeding Trial ◽  
Body Weights ◽  
Selection For ◽  
Carcass Merit ◽  
The Impact ◽  
Daily Gain

ObjectivesProfitability in the beef industry has narrow margins regulated by revenue from output traits like growth and carcass merit, but profitability is also largely impacted by input expenses like feed costs. Selecting for improvements in feed efficiency during the finishing phase, one of the most feed intensive segments of the industry, can help to mitigate those input costs. This study compared growth performance, feed efficiency, body composition, and carcass characteristics in Angus steers (n = 321) from bulls divergently selected for feed efficiency and marbling.Materials and MethodsAngus sires were selected based on high (10th percentile or better) and low (85th percentile or worse) residual average daily gain (RADG) EPD as well as high (fifth percentile or better) and average (near 50th percentile) marbling (MARB) EPD. These criteria resulted in a 2 × 2 factorial design with four breeding lines: high RADG/high MARB, high RADG/average MARB, low RADG/high MARB, low RADG/average MARB. Data were analyzed using MIXED procedures of SAS with RADG and MARB as main effects. Significance was set at α = 0.05. Generation was also analyzed, where generation one (GEN1) steers were from a selected sire while generation two (GEN2) steers were from a selected sire and a selected dam.ResultsUltrasound and carcass data revealed no differences (P ≥ 0.12) in 12th rib backfat thickness from weaning through slaughter for the RADG EPD groups. Yield grade and dressing percent did not differ (P ≥ 0.56) across RADG or MARB groups. At the beginning and end of the feeding trial, the high RADG (P ≤ 0.02) group had larger ultrasound ribeye area (REA) than the low RADG group. Carcass REA tended (P = 0.08) to be larger in the high versus low RADG steers. During the feedlot trial and through slaughter, body weight was heavier (P ≤ 0.006) for the high versus low RADG steers but did not differ (P ≥ 0.44) across MARB EPD. Feed efficiency measures did not differ (P ≥ 0.32) across RADG or MARB groups apart from the tendency (P = 0.08) for residual feed intake to be lower in the high versus low RADG steers. Marbling scores differed (P ≤ 0.04) across RADG and MARB groups with the low RADG steers and the high MARB steers having improved marbling. The quality grade distribution across MARB EPD revealed that the average MARB steers graded 73% Choice and 25% Prime while the high MARB steers graded 56% and 42%, respectively. Slice shear force did not differ (P ≥ 0.32) across RADG or MARB EPD. Body weights tended (P = 0.06) to be heavier at the start of the feeding trial for GEN1 versus GEN2 steers. Total gain, average daily gain, and feed to gain (F:G) differed by generation (P ≤ 0.007) with increased rates of gain and reduced F:G in the GEN2 versus GEN1 steers. Body weights did not differ (P = 0.72) across GEN at the end of the feeding trial. Backfat thickness at the start and end of the feedlot phase was less (P ≤ 0.03) and marbling score was improved (P = 0.02) in the GEN2 versus GEN1 steers, respectively.ConclusionThese results suggest that selection using RADG EPD has negligible impacts on meat quality; and that progress in selection for efficiency can be achieved while advancing carcass quality and value. Furthermore, continued divergent selection for feed efficiency and marbling has the potential to improve feed efficiency through advancements in the rate of gain, while enhancing carcass merit through marbling.

Feed requirements for maintenance and growth of one-year-old Angus steers selected for either fast or slow yearling growth rate

1991 ◽  
Vol 31 (5) ◽  
pp. 591 ◽  
Author(s):  
RM Herd ◽  
PA Speck ◽  
PC Wynn
Keyword(s):  
Growth Rate ◽  
Average Daily Gain ◽  
Biological Efficiency ◽  
Angus Cattle ◽  
High Line ◽  
Feed Utilisation ◽  
Metabolisable Energy ◽  
Selection For ◽  
One Year ◽  
Daily Gain

The efficiency of feed utilisation for maintenance and growth at 1 year of age was examined in 11 steers from each of 2 lines of Angus cattle selected for either fast (high line) or slow (low line) average daily gain to 1 year of age. The steers were established on a range of dietary energy intakes for 2 trials, each of 3 weeks duration. Fasted liveweights (LW) were measured at the start and end of each trial. Body fat was estimated at the end of the first trial. At the start of the experiment the high line steers were heavier (P<0.001) than the low line steers (278 v. 203 kg). The high line steers required more (P<0.001) feed per day [48.0 v. 39.3 MJ metabolisable energy (ME)] to maintain their greater LW but required less (P = 0.05) feed to sustain each kilogram of this LW (0.174 v. 0.192 MJ ME/kg LW) and, so, were more efficient. There was no difference in the efficiency of feed use for gain in LW (0.042 v. 0.040 kg LW/MJ ME.day). However, after adjusting feed intakes for the different mature sizes (A) of the 2 lines, there was no difference in the biological efficiency of feed use for either maintenance (0.369 v. 0.359 MJ ME/kg A0.73) or gain (5.45 v. 4.37 kg LW/MJ ME.kg A0.73). These results suggest that divergent selection for growth rate in this study has produced different-sized animals whose ability to convert feed to gain in LW has not been altered.

MASS SELECTION FOR POST-WEANING GROWTH IN SWINE. IV. SELECTION RESPONSE AND CONTROL POPULATION STABILITY

1976 ◽  
Vol 56 (4) ◽  
pp. 783-790
Author(s):  
G. W. RAHNEFELD ◽  
I. GARNETT
Keyword(s):  
Additive Genetic Variance ◽  
Average Daily Gain ◽  
Selection Response ◽  
Relative Magnitude ◽  
Control Population ◽  
Mass Selection ◽  
Gene Effects ◽  
Selection For ◽  
And Control ◽  
Daily Gain

Recurrent mass selection for post-weaning average daily gain was practiced for 11 generations in a population of Lacombe swine. Response to selection was assessed from predicted response, 0.241 ± 0.023 kg; observed response, 0.146 ± 0.018 kg; estimated heritability, 0.327 ± 0.031; and realized heritability, 0.198 ± 0.016. Observed response was estimated to be 0.61 of the predicted. Examination of additive genetic variance, selection differentials, drift variance, inbreeding and regression of post-weaning average daily gain on generation time indicated that the pedigreed Yorkshire control population served as an adequate control. Gene effects were not found to be dependent on the sex of the organism as assessed by the genetic correlation between sexes, covariance between half-sib family means and the relative magnitude of parent–offspring-based estimates of heritability.

scholarly journals Genetic parameters and predicted response to selection for lean growth in an Australian commercial nucleus pig herd

2000 ◽  
Vol 51 (7) ◽  
pp. 833 ◽  
Author(s):  
Nguyen Hong Nguyen ◽  
Cam P. McPhee ◽  
Claire M. Wade ◽  
Brian G. Luxford
Keyword(s):  
Growth Rate ◽  
Genetic Parameters ◽  
Average Daily Gain ◽  
Genetic Correlations ◽  
Genetic Response ◽  
Lean Growth ◽  
Derivative Free ◽  
Total Data ◽  
Selection For ◽  
Daily Gain

Genetic parameters for performance traits in a pig population were estimated using a multi-trait derivative-free REML algorithm. The 2590 total data included 922 restrictively fed male and 1668 ad libitum fed female records. Estimates of heritability (standard error in parentheses) were 0.25 (0.03), 0.15 (0.03), and 0.30 (0.05) for lifetime daily gain, test daily gain, and P2-fat depth in males, respectively; and 0.27 (0.04) and 0.38 (0.05) for average daily gain and P2-fat depth in females, respectively. The genetic correlation between P2-fat depth and test daily gain in males was –0.17 (0.06) and between P2-fat and lifetime average daily gain in females 0.44 (0.09). Genetic correlations between sexes were 0.71 (0.11) for average daily gain and –0.30 (0.10) for P2-fat depth. Genetic response per standard deviation of selection on an index combining all traits was predicted at $AU120 per sow per year. Responses in daily gain and backfat were expected to be higher when using only male selection than when using only female selection. Selection for growth rate in males will improve growth rate and carcass leanness simultaneously.

Effectiveness of selection for growth rate in Zebu × British crossbred cattle. II.* Post-weaning growth and genetic estimates

1975 ◽  
Vol 26 (6) ◽  
pp. 1093 ◽  
Author(s):  
GW Seifert
Keyword(s):  
Growth Rate ◽  
Birth Weight ◽  
Average Daily Gain ◽  
Genetic Correlations ◽  
Female Offspring ◽  
High Birth Weight ◽  
Environmental Correlations ◽  
Final Weight ◽  
Selection For ◽  
Daily Gain

The response to one generation of selection for weight per day of age at 18 months (W/Af), in Africander cross (AX) and Brahman cross (BX) cattle, was evaluated in the female offspring of the up and down selected parents. The high W/A< line gained significantly more than the low line over a year from weaning. The advantage of the high W/A line occurred during flush nutritional periods. The realized heritability (h2) of W/Af at 18 months was 0.52, while the estimates of h2 from mid-parental means computed within sires was higher. Heritability estimates for birth weight (Wb), weaning weight per day of age (W/Aw), pre-weaning average daily gain (Gbw) and total average daily gain from birth to final weight (Gt) were all high, while the estimate for post-weaning average daily gain from weaning to final weight (Gpw) was low. The correlated responses of all the traits were high. The genetic correlations estimated from the response and the parent-offspring regressions were all positive and high. Birth weight was the most highly correlated with Gt. All phenotypic correlations were positive but lower than the genetic correlations, the correlation between Gbw and Gpw being the lowest. Environmental correlations between birth weight and pre-weaning traits were essentially zero, and between birth weight and post-weaning traits and Gt, negative. Weight per day of age at 18 months appeared to be the most efficient and practical single trait to select beef cattle for increased growth rate.

scholarly journals Studies on dehorning steers in Alberta feedlots

1991 ◽  
Vol 71 (4) ◽  
pp. 1241-1247 ◽  
Author(s):  
L. A. Goonewardene ◽  
R. K. Hand
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Average Daily Gain ◽  
Daily Gain

The study contained 507 crossbred steers from seven lots in five owner-operated feedlots. The objective was to determine the effects of dehorning (DH) at the feedlot on growth rate, compared to a control (CO) consisting of polled or previously dehorned steers. Significant (P < 0.01) treatment differences (DH = 1.11 ± 0.01 kg d−1, CO = 1.16 ± 0.01 kg d−1) and treatment × lot interaction were observed for average daily gain from 0 to 106 d. Key words: Dehorning, steers, feedlot, gain

EFFECT OF ANABOLIC IMPLANT AND IONOPHORE ON THE PERFORMANCE OF GRAZING STEERS

1987 ◽  
Vol 67 (2) ◽  
pp. 461-467 ◽  
Author(s):  
L. M. RODE
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Factorial Design ◽  
Key Words ◽  
Average Daily Gain ◽  
Grazing Season ◽  
17Β Estradiol ◽  
Anabolic Implants ◽  
Daily Gain ◽  
Cattle Feedlot

In a 110-d grazing study, 75 yearling steers were left unimplanted or implanted at Day 0 with 24 mg 17β-estradiol, 36 mg zearanol, 72 mg zearanol, or 36 mg zearanol at Day 0 and 84. Within each implant group, steers were also supplemented with barley (0.5 kg head−1 d−1) with or without lasalocid (0.75 mg kg body weight−1 d−1) or were given no supplement in a 5 × 3 factorial design. Average daily gain (ADG) for all implanted steers was 17.5% greater (0.94 vs. 0.80 kg d−1) than for unimplanted steers (P < 0.01). Increasing the dosage of zearanol from 36 to 72 mg extended the time over which ADG was increased but total liveweight gain and ADG over the 110-d grazing season were similar for all implant types. A second implant of zearanol (2 × 36 mg) increased ADG during the final 26 d of the pasture phase and during the drylot period, compared with 72 mg zearanol given initially. Barley + lasalocid-supplemented steers had ADG 17.3% greater (1.02 vs. 0.87 kg d−1) than barley-supplemented steers (P < 0.01). During the following drylot phase, when no lasalocid was fed, ADG was lower (P < 0.10) for steers that had previously received lasalocid than for other groups. No interactions were observed between implant and supplement type. Thus, the anabolic implants and ionophores used in this study are additive in improving growth rate. Key words: Cattle, feedlot, grazing, lasalocid, zearanol, 17β-estradiol, growth

Carcass quality characteristics of swine selected for reduced backfat thickness and increased growth rate

1993 ◽  
Vol 73 (3) ◽  
pp. 483-494 ◽  
Author(s):  
R. L. Cliplef ◽  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Subcutaneous Fat ◽  
Quality Characteristics ◽  
Backfat Thickness ◽  
Carcass Quality ◽  
Growth Selection ◽  
Selection For ◽  
Seven Generations

Selection for reduced backfat thickness and increased growth rate in Yorkshire (eight generations) and Hampshire (seven generations) swine resulted not only in less backfat but carcasses which were longer with higher percentages of dissectible lean in the fresh hams. Selected carcasses also had a higher incidence of more severe loin lean-fat separation and subjectively perceived softness in the subcutaneous fat. Boar carcasses were longer and leaner with smaller loin eye areas compared with gilt carcasses. Key words: Swine, carcass quality, backfat, growth, selection

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