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Genetic relationships of measures of residual feed intake and daily feed intake with serum IGF-I concentrations at 8 wk of age and at 105 kg of BW, serum leptin concentration at 105 kg of BW, meat quality, and different fat accumulation traits on 834 Duroc pigs in 7 generations were estimated. Two measures of residual feed intake were estimated from the differences between actual and predicted feed intake: phenotypic residual feed intake ([RFI.sub.phe]) and nutritional residual feed intake ([RFI.sub.nut]). Meat quality traits included drip loss, cooking loss, pork color score, pork lightness ([L.sup.*]), and pH, whereas fat accumulation traits were subcutaneous fat, intermuscular fat, and total fat percent at 5-6th thoracic vertebra; subcutaneous fat, intermuscular fat, abdominal fat, and total fat percent at one-half body length and at last thoracic vertebra, and seam fat score. The IGF-I concentrations at 8 wk of age and 105 kg of BW had weak genetic correlations with measures of residual feed intake and daily feed intake (absolute values ranging from 0.14 to 0.24). The genetic correlations between measures of residual feed intake and serum leptin concentration were strong and positive ([r.sub.g] with [RFI.sub.phe] and [RFI.sub.nut] were 0.74 and 0.80, respectively). Residual feed intake was moderately but negatively correlated with cooking loss ([r.sub.g] with [RFI.sub.phe] and [RFI.sub.nut] were -0.42 and -0.49, respectively), whereas daily feed intake was moderately and positively correlated with drip loss and pH (0.33 and 0.36, respectively). Daily feed intake was also moderately correlated with subcutaneous fat accumulations at the 5-6th thoracic vertebra (0.31) and one-half body length (0.31) regions and was strongly correlated with accumulations at the last thoracic vertebra region (0.57). The genetic correlations between daily feed intake and intermuscular fat accumulations at all of the carcass sites were strong (0.60, 0.76, and 0.56 for intermuscular fat at 5-6th thoracic vertebra, one-half body length, and last thoracic vertebra, respectively). Residual feed intake was strongly and positively correlated with all of the fat accumulation traits (ranging from 0.53 to 0.88). The results indicate that reducing residual feed intake (increased efficiency) would lead to increased cooking loss and darkness, and decreased serum leptin concentration, fat accumulations at the different sites, and seam fat at the 6th rib interface of pork carcasses. Key words: carcass trait, fat accumulation, genetic relationship, hormone trait, performance trait

To identify DNA markers associated with performance, carcass, and meat production traits including muscle postmortem cathepsin activity, several porcine genes encoding for lysosomal proteinases (cathepsin B, CTSB; cathepsin D, CTSD; cathepsin F, CTSF; cathepsin H, CTSH; cathepsin L, CTSL; and cathepsin Z, CTSZ) and for a cathepsin inhibitor (cystatin B) were investigated. Single nucleotide polymorphisms were identified in CTSD, CTSH, CTSL, and CTSZ genes with a combination of in silico expressed sequence tag database mining and single-strand conformation polymorphism analysis. Sequencing and PCR-RFLP protocols were used to validate the identified polymorphisms. Allele frequencies at these loci were investigated in Italian Large White, Landrace, Duroc, Pietrain, Belgian Landrace, Hampshire, and Meishan breeds. Genotyping CTSD and CTSH markers made it possible to genetically map these genes to SSC 2 and 7, respectively. Markers in CTSD, CTSH, CTSL, and CTSZ genes, together with mutations we previously reported in cystatin B, CTSB, and CTSF genes, were genotyped in an Italian Large White sib-tested population (272 or 482 animals). For these animals, meat quality traits (cathepsin B activity, pH measured at 2 h postmortem, pH measured at 24 h postmortem, glycogen, lactate, and glycolytic potential of semimembranosus muscle) and EBV for ADG, lean cuts (LC), backfat thickness (BFT), ham weight (HW), and feed:gain ratio (FGR) were determined. Analyzed markers did not show any association with muscle cathepsin B activity. Thus, it could be possible that different genes, other than these investigated candidates, affect this trait, which is correlated with the excessive softness defect of dry-cured hams. The results of association analysis confirmed the effects we already reported in another study for CTSF on ADG (P = 0.008), LC (P = 0.001), and BFT (P = 0.02). Moreover, CTSD was associated with ADG, LC (P < 0.0001), BFT, HW, and FGR (P < 0.001); CTSH was associated with FGR (P = 0.026); and CTSZ was associated with ADG (P = 0.006), LC (P = 0.01), HW (P = 0.024), and FGR (P = 0.029). The biochemical and physiological functions of the lysosomal proteinases, together with the results obtained in our investigation, suggest that the cathepsin gene family might play important roles affecting economic traits in pigs. Key words: candidate gene, cathepsin, cystatin, meat production, pig, single nucleotide polymorphism

A genome-wide scan for QTL affecting economically important traits in beef production was performed using an [F.sub.2] resource family from a Japanese Black x Limousin cross, where 186 [F.sub.2] animals were measured for growth, carcass, and meat-quality traits. All family members were genotyped for 313 informative microsatellite markers that spanned 2,382 cM of bovine autosomes. The centromeric region of BTA2 contained significant QTL (i.e., exceeding the genome-wide 5% threshold) for 5 carcass grading traits [LM area, beef marbling standards (BMS) number, luster, quality grade, and firmness), 8 computer image analysis (CIA) traits [LM lean area, ratio of fat area (RFA) to LM area, LM area, RFA to musculus (M.) trapezius area, M. trapezius lean area, M. semispinalis lean area, RFA to M. semispinalis area, and RFA to M. semispinalis capitis area], and 5 meat quality traits (contents of CP, crude fat, moisture, C16:1, and C18:2 of LM). A significant QTL for withers height was detected at 80.3 cM on BTA5. We detected significant QTL for the C14:0 content in backfat and C14:0 and C14:1 content in intermuscular fat around the 62.3 to 71.0 cM region on BTA19 and for C14:0, C14:1, C18:1, and C16:0 content and ratio of total unsaturated fatty acid content to total SFA content in intramuscular fat at 2 different regions on BTA19 (41.1 cM for C14:1 and 62.3 cM for the other 4 traits). Overall, we identified 9 significant QTL regions controlling 27 traits with genome-wide significance of 5%; of these, 22 traits exceeded the 1% genome-wide threshold. Some of the QTL affecting meat quality traits detected in this study might be the same QTL as previously reported. The QTL we identified need to be validated in commercial Japanese Black cattle populations. Key words: bovine, [F.sub.2] family, meat quality, quantitative trait loci

Many QTL analyses related to meat production and meat quality traits have been carried out using an [F.sub.2] resource population produced by crossing 2 genetically different breeds. This experiment was intended to investigate whether these QTL were segregating in a purebred Duroc population that had been selected for meat production and meat quality traits during 7 generations. Sus scrofa chromosome 7, for which significant QTL of intramuscular fat and many other traits have already been reported, was studied. The polymorphism of 10 microsatellite markers that were arranged at about 20-cM intervals was investigated on 1,004 pigs. In the selected population, 954 progeny were produced from mating of 99 sires and 286 dams. The QTL analysis for a full-sib family population was examined with the multigeneration pedigree structure of the population. Variance component analysis was used to detect QTL in this population and was examined for the multigeneration pedigree population. In this study, multigenerational pedigree estimated identical by descent coefficients among sibs were produced using Markov chain Monte Carlo methods. The maximum likelihood of odds score was found at the 70-cM position for the LM area, at the 0-cM position for the pork color standard, and at the 120-cM position for the number of thoracic vertebra, but no significant QTL for intramuscular fat were detected on SSC 7. These results indicate that QTL analysis via a variance component method within a purebred population was effective to determine that QTL were segregating in a population of purebred Durocs. Key words: Duroc pig, meat quality, multiple generation, quantitative trait loci, selected population

Residual feed intake (RFI) is a measure of feed efficiency defined as the difference between the observed feed intake and that predicted from the average requirements for growth and maintenance. The objective of this study was to evaluate the response in a selection experiment consisting of a line selected for low RFI and a random control line and to estimate the genetic parameters for RFI and related production and carcass traits. Beginning with random allocation of purebred Yorkshire littermates, in each generation, electronically measured ADFI, ADG, and ultrasound backfat (BF)were evaluated during a ~40- to ~ll5-kg of BW test period on ~90 boars from first parity and ~90 gilts from second parity sows of the low RFI line. After evaluation of first parity boars, ~12 boars and ~70 gilts from the low RFI line were selected to produce ~50 litters for the next generation. Approximately 30 control line litters were produced by random selection and mating. Selection was on EBV for RFI from an animal model analysis of ADFI, with ontest group and sex (fixed), pen within group and litter (random), and covariates for interactions of on- and offtest BW, on-test age, ADG, and BF with generations. The RFI explained 34% of phenotypic variation in ADFI. After 4 generations of selection, estimates of heritability for RFI, ADFI, ADG, feed efficiency (FE, which is the reciprocal of the feed conversion ratio and equals ADG/ADFI), and ultrasound-predicted BF, LM area (LMA), and intramuscular fat (IMF) were 0.29, 0.51, 0.42, 0.17, 0.68, 0.57, and 0.28, respectively; predicted responses based on average EBV in the low RFI line were -114, -202, and -39 g/d for RFI (= 0.9 phenotypic SD), ADFI (0.9 SD), and ADG (0.4 SD), respectively, and 1.56% for FE (0.5 SD), -0.37 mm for BF (0.1 SD), 0.35 [cm.sup.2] for LMA (0.1 SD), and -0.10% for IMF (0.3 SD). Direct phenotypic comparison of the low RFI and control lines based on 92 low RFI and 76 control gilts from the second parity of generation 4 showed that selection had significantly decreased RFI by 96 g/d (P = 0.002) and ADFI by 165 g/d (P < 0.0001). The low RFI line also had 33 g/d lower ADG (P = 0.022), 1.36% greater FE (P = 0.09), and 1.99 mm less BF (P = 0.013). There was not a significant difference in LMA and other carcass traits, including subjective marbling score, despite a large observed difference in ultrasound-predicted IMF (-1.05% with P < 0.0001). In conclusion, RFI is a heritable trait, and selection for low RFI has significantly decreased the feed required for a given rate of growth and backfat. Key words: feed efficiency, pig, residual feed intake, selection

Feed intake and feed efficiency of beef cattle are economically relevant traits. The study was conducted to identify QTL for feed intake and feed efficiency of beef cattle by using genotype information from 100 microsatellite markers and 355 SNP genotyped across 400 progeny of 20 Angus, Charolais, or Alberta Hybrid bulls. Traits analyzed include feedlot ADG, daily DMI, feed-to-gain ratio [F:G, which is the reciprocal of the efficiency of gain (G:F)], and residual feed intake (RFI). A mixed model with sire as random and QTL effects as fixed was used to generate an F-statistic profile across and within families for each trait along each chromosome, followed by empirical permutation tests to determine significance thresholds for QTL detection. Putative QTL for ADG (chromosome-wise P < 0.05) were detected across families on chromosomes 5 (130 cM), 6 (42 cM), 7 (84 cM), 11 (20 cM), 14 (74 cM), 16 (22 cM), 17 (9 cM), 18 (46 cM), 19 (53 cM), and 28 (23 cM). For DMI, putative QTL that exceeded the chromosome-wise P < 0.05 threshold were detected on chromosomes 1 (93 cM), 3 (123 cM), 15 (31 cM), 17 (81 cM), 18 (49 cM), 20 (56 cM), and 26 (69 cM) in the across-family analyses. Putative across-family QTL influencing F:G that exceeded the chromosome-wise P < 0.05 threshold were detected on chromosomes 3 (62 cM), 5 (129 cM), 7 (27 cM), 11 (16 cM), 16 (30 cM), 17 (81 cM), 22 (72 cM), 24 (55 cM), and 28 (24 cM). Putative QTL influencing RFI that exceeded the chromosome-wise P < 0.05 threshold were detected on chromosomes 1 (90 cM), 5 (129 cM), 7 (22 cM), 8 (80 cM), 12 (89 cM), 16 (41 cM), 17 (19 cM), and 26 (48 cM) in the across-family analyses. In addition, a total of 4, 6, 1, and 8 chromosomes showed suggestive evidence (chromosome-wise, P < 0.10) for putative ADG, DMI, F:G, and RFI QTL, respectively. Most of the QTL detected across families were also detected within families, although the locations across families were not necessarily the locations within families, which is likely because of differences among families in marker informativeness for the different linkage groups. The locations and direction of some of the QTL effects reported in this study suggest potentially favorable pleiotropic effects for the underlying genes. Further studies will be required to confirm these QTL in other populations so that they can be fine-mapped for potential applications in marker-assisted selection and management of beef cattle. Key words: beef cattle, feed intake, feed efficiency, quantitative trait loci

Body composition traits have potential use in fish breeding programs as indicator traits for selective improvement of feed efficiency. Moreover, feed companies are increasingly replacing traditional fish meal (FM) based ingredients in feeds for carnivorous farmed fish with plant protein ingredients. Therefore, genetic relationships of composition and feed utilization traits need to be quantified for both current FM-based and future plant-based aquaculture feeds. Individual whole-body lipid% and protein%, daily gain (DG), ADFI, and G:F (daily gain/daily feed intake) were measured on 1,505 European whitefish (Coregonus lavaretus) from 70 half/full-sib families reared in a split-family design with either a typical FM or a novel soybean meal (SBM) based diet. Diet-specific genetic parameters were estimated with multiple-trait animal models. Lipid% was significantly greater in the FM diet group than in the SBM group, even independent of final BW or total feed intake. In both diets, lipid% showed moderate heritability (0.12 to 0.22) and had positive phenotypic and genetic correlations with DG (0.37 to 0.82) and ADFI (0.36 to 0.88). Therefore, selection against lipid% can be used to indirectly select for lower feed intake. Protein% showed low heritability (0.05 to 0.07), and generally very weak or zero correlations with DG and ADFI. In contrast to many previous studies on terrestrial livestock, lipid% showed zero or very weak phenotypic and genetic correlations with G:F. However, selection index calculations demonstrated that simultaneous selection for high DG and reduced lipid% could be used to indirectly increase G:F; this strategy increased absolute genetic response in G:F by a factor of 1.5 to 1.6 compared with selection on DG alone. Lipid% and protein% were not greatly affected by genotype-diet environment interactions, and therefore, selection strategies for improving body composition within current FM diets should also improve populations for future SBM diets. Key words: feed efficiency, genetic selection, genotype-environment interaction, lipid, protein

The purpose of this study was to estimate genetic parameters for ADG, backfat thickness and loin eye area (LEA), and measures of feed intake and efficiency for purebred Large White boars born from 1990 to 1997. Boars from 60% of the litters were culled at weaning based on a maternal breeding value (index) of the dam, and remaining boars (n = 26,706) were grown to 100 d of age. Selection of boars for individual pen testing was based on a combination of growth and maternal indices. Boars were fed a corn-soybean meal diet that was 1.14% lysine, 19% protein, and 3,344 kcal/kg ME for approximately 77 d. Boars were weighed at the beginning and end of the test, and feed intake was recorded. Daily feed intake (DFI), ADG, and feed:gain ratio (FG) were computed. Four measures of residual feed intake (RFI) were estimated as the difference between actual feed intake and that predicted from models that included 1) initial test age and weight and test ADG (RFI1); 2) initial test age and weight, test ADG, and backfat (RFI2); 3) initial test age and weight, test ADG, and LEA (RFI3); and 4) initial test age and weight, test ADG, backfat, and LEA (RFI4). Genetic parameters were estimated using an animal model and single- or multiple-trait DFREML procedures. Models included fixed effects of contemporary groups and initial test age as a covariate and random animal and litter effects. Heritability estimates for test ADG, DFI, FG, backfat, LEA, RFI1, RFI2, RFI3, and RFI4 were .24, .23, .16, .36, .24, .17, .11, .15, and .10, respectively. Genetic correlations between ADG and backfat, ADG and LEA, ADG and DFI, and ADG and FG were .37, .36, .82, and -.32, respectively. Genetic correlations between ADG and measures of residual feed intake ranged from .11 to .18. Genetic correlations of backfat with LEA, DFI, and FG were -.27, .64, and .40, respectively. Genetic correlations of backfat with RFI measures were higher when backfat was not included in the estimation of RFI. Genetic correlations for LEA with DFI and FG were 0 and -.52, respectively. Genetic correlations for LEA with RFI measures were all negative and ranged from -.31 to -.51. Genetic correlations indicate that selection for reduced RFI could be made without adversely affecting ADG. Backfat should also decrease, and LEA should increase. The amount of change in backfat or LEA would depend on the measure of RFI used. Key Words: Pigs, Genetic Parameters, Feed Intake

An experiment at the Agricultural University of Norway provided data to estimate genetic parameters of roughage intake (RI), fat-corrected milk yield (FCM), smoothed BW (SW), weight change (WC), and energy balance (EB). Weekly measurements were averaged in four consecutive 6-wk periods after parturition for each of 331 primiparous Norwegian cows of 20 sires. Amount of concentrate fed was adjusted according to stage of lactation and cows were randomly assigned to a normal or a low level. Animals were given ad libitum access to grass silage. Multiple-trait animal models with all additive genetic relationships incorporated were applied to the subsets of all averages of one trait and all averages in one period. Each model contained for every trait 165 observations, 24 mo-year seasons of calving, and 313 additive genetic effects. (Co)variance components were estimated by an EM-REML algorithm. The heritability of RI increased with negative energy balance from .25 to .86, whereas the estimates were approximately .2 for FCM, .6 to .7 for SW, and .03 to .4 for WC and EB. The correlations between RI and FCM were .37 to .58 phenotypically and -.11 to .88 genetically; between RI and SW they were .57 to .73 phenotypically and .7 to 1 genetically; between FCM and SW they were -.06 to .35 phenotypically and -.33 to .70 genetically; and between WC and EB they were .52 to .92 phenotypically and -.09 to .88 genetically. Correlations between WC and EB and other traits were inconsistent over periods and had very high SE.

Retained heterosis for different measures of gain efficiency was estimated in |F.sub.3^ generation castrate male progeny in three composite populations finished on two levels of dietary energy density (2.82 and 3.07 Mcal of ME and 11.50% CP) and serially slaughtered at four end points at intervals of 20 to 22 d. Breed effects were evaluated in nine parental breeds (Red Poll |R^, Hereford |H^, Angus |A^, Limousin |L^, Braunvieh |B^, Pinzgauer |P^, Gelbvieh |G^, Simmental |S^, and Charolais |C^) that contributed to the three composite populations (MARC I = 1/4 B, 1/4 C, 1/4 L, 1/8 H, 1/8 A; MARC II = 1/4 G, 1/4 S, 1/4 H, 1/4 A; and MARC III = 1/4 R, 1/4 P, 1/4 H, and 1/4 A). Gain efficiency was evaluated in time constant (0 to 207 d), gain constant (310 to 540 kg), carcass weight constant (333 kg), and retail product weight constant (225 and 210 kg) end points and to different marbling score and longissimus muscle fat end points. Expressions of gain efficiency included live weight gain/megacalories of ME and retail product weight/megacalories of ME. Significant differences were observed among breeds in all measures of gain efficiency. Breeds that had the smallest weight to maintain tended to be more efficient in live weight gain in the time constant period, whereas breeds with the highest rate of gain tended to be more efficient in the gain constant period. To marbling score or longissimus muscle fat end points, breeds with the lowest marbling scores and smallest percentage fat in the longissimus muscle on an age constant basis (e.g., Limousin and Gelbvieh) tended to be less efficient, whereas breeds with the highest marbling score and highest percentage of fat in the longissimus muscle on an age constant basis (e.g., Hereford and Angus) tended to be more efficient. Breeds with the highest percentage of retail product (Limousin and Gelbvieh) were more efficient to retail product weight end points, or when retail product weight was the measure of output. Steers fed the higher energy density diet were more efficient in live weight gain to time constant, live weight gain constant, marbling score constant, and longissimus fat constant end points and were more efficient in the production of retail product weight to retail product weight end points because of the shorter period of maintenance. Retained heterosis was not consistent among composites in different measures of gain efficiency. Higher initial weights resulting in greater requirements for maintenance had a negative effect in composites for most measures of gain efficiency.

Five generations of laying hens in a breeding experiment to improve income minus feed cost (IFC) resulted in increased egg weight which adversely affected hatchability. The selection procedure was modified based on restricted BLUP (rBLUP) breeding values in the next two generations to continue selecting for higher IFC while keeping egg weight constant. The restriction reduced genetic gain in IFC from 4.1% to 2.0% in the sixth generation, and from 3.9% to 2.2% in the seventh generation. The average estimate of breeding value for egg weight remained nearly constant after exhibiting strong increase in the first five generations.