Backfat Thickness Research Articles

PSXI-6 The Effects Cattle Breed (Holstein Vs Angus × Holstein) on Growth Performance, Energetic Efficiency, and Carcass Characteristics of Calf-Fed Steers

Abstract Objective of the current study was to evaluate the effects of cattle breed (Holstein vs Angus × Holstein) on growth performance, energetic efficiency, and carcass characteristics of calf-fed steers. Eighty Holstein (HOL), initial body weight (IBW) of 128.7 ± 3 kg, and 80 Angus × Holstein cross (CROS) with IBW of 127.1 ± 3 kg, were blocked by IBW and randomly assigned to 40 pens (4 steers/pen; 20 pens per breed). All steers were fed a similar steam-flaked corn-based diet (63.5% steam-flaked corn, 12.0% hay, 17.5% of dry distillers grains with solubles, 4.0% cane molasses, and 3.0% vitamin/mineral supplement). All cattle were slaughtered after 328 days of feeding. There was no effect (P ≥ 0.13) of cattle breed on final body weight (615 ± 22 kg) and overall average daily gain (1.48 ± 0.07 kg/day). However, calf-fed HOL steers had greater (P = 0.04) overall dry matter intake compared with calf-fed CROS steers (8.06 vs. 7.79 ± 0.39 kg/day; respectively). Therefore, calf fed CROS steers had greater (P ≤ 0.01) grain to feed ratio compared with calf-fed HOL steers (0.192 vs. 0.182 ± 0.005; respectively). Moreover, calf-fed CROS steers had greater (P < 0.01) utilization of dietary net energy for maintenance (2.29 vs. 2.29 ± 0.06 Mcal/kg; respectively) and gain (1.51 vs 1.61 ± 0.06 Mcal/kg; respectively) compared with calf-fed HOL steers. Calf-fed CROS steers had greater (P ≤ 0.02) hot carcass weight (HCW; 386.3 vs. 375.2 ± 14.7 kg; respectively), dressing percentage (DP; 62.3 vs. 61.4 ± 1.05%; respectively), longissimus muscle area (LMA; 86.9 vs. 79.1 ± 4.83 cm2; respectively), backfat thickness (0.89 vs. 0.55 ± 0.12; respectively), and marbling score (538 vs. 449 ± 48; respectively). However, there was no effect (P = 0.26) of cattle breed on calculated USDA yield grade (2.94 ± 0.24). Moreover, there was no effect (P = 0.39) of cattle breed on incidence of liver abscesses. Therefore, cross breeding calf-fed Angus × Holstein increased HCW, DP, LMA, and marbling compared with purebred calf-fed Holstein steers. Moreover, regardless of cattle breed, calf-fed steers in the current study had only 3.75% of liver with abscess.

249 The Effects of Breed and Early Supplementation on Bovine Intramuscular Fat Deposition, Adipogenic and Lipogenic Gene Expression

Abstract Wagyu cattle are known to deposit greater amounts of intramuscular fat, which can directly increase quality grade and carcass value. Supplementation can positively influence animal production and overall nutrient acquisition when used strategically. The objectives of this study were to evaluate 1) the effect of breed and early supplementation on intramuscular and subcutaneous fat deposition in Wagyu and Hereford cross calves, and 2) changes in adipogenic and lipogenic gene expression in longissimus muscle (LM) biopsies from Wagyu and Hereford cross calves during an early supplementation period. Angus cows (n = 34) were artificially inseminated with semen from a Wagyu bull. A Hereford bull was utilized as a clean-up bull. From this breeding, Wagyu cross steers (n = 8) and Hereford cross steers (n = 9) were produced and were placed on study on day 100 of age. At this time, calves were allowed access to four SuperSmart Feeder stalls and were individually supplemented with steam-rolled corn at 0.5% body weight (BWT). Calves were ultrasounded on day 0, day 43, and day 86 of the study to evaluate intramuscular fat deposition and backfat thickness. An longissimus muscle (LM) biopsy was taken on day 0 and day 86 of the study to evaluate gene expression. Supplemented steers tended (P < 0.10) to have more backfat than non-supplemented steers. Intramuscular fat amount differed (P < 0.05) by breed, while ribeye area tended (P < 0.10) to differ by breed. Wagyu exhibited a greater (P < 0.05) amount of intramuscular fat at the beginning and at the end of the study. Breed did not (P > 0.05) influence backfat thickness. Neither breed nor supplementation affected (P > 0.05) average daily gain or final body weights. Platelet-derived growth factor alpha (PDGRFA) and SREBP cleavage-activating protein (SCAP) differed (P < 0.05) between biopsy phases. Fatty acid binding protein-4 (FABP4) and stearoyl-coA desaturase-1 (SCD1) did not differ (P > 0.05) between breed or biopsy phase. In conclusion, changes in gene expression could indicate enhanced preadipocyte proliferation during this stage of calf development. Overall, supplementation altered backfat deposition but did not alter intramuscular fat levels. Opposingly, sire breed influenced intramuscular fat levels at an early age. A deeper understanding of the physical and molecular effects of supplementation and sire breed could provide additional avenues for manipulating adipose tissue.

354 Effect of Finishing System on Growth, Efficiency, and Carcass Quality of Dairy × Beef Hybrids

Abstract Our objective was to determine how calf-fed or yearling finishing systems affect the performance and efficiency of dairy-beef crossbred steers. Dairy-beef hybrid steers were acquired from Land O’ Lakes Calf Milk Research Facility at Grey Summit, Missouri at 12-wk (BW /SD) of age and transported to Willard Sparks Beef Research Center (WSBRC). Upon arrival at WSBRC, steers were weighed, vaccinated, treated for parasites, and implanted with 36 mg of zeranol (Ralgro). Alternating groups of steers were placed either directly on finishing diets (FIN) or on high-quality pasture and supplementation for 5 to 6 mo before returning to WSBRC for finishing (GRW/FIN). Steers in FIN were grown on successively higher energy growing diets through d 112, stepping up to a 20% roughage growing diet from d 28 to 112. On d 112, FIN steers were transitioned to a 12% roughage finishing diet. A final 8% roughage finishing was fed to FIN steers from d 224 to slaughter. Steers in FIN were reimplanted with Ralgro on d 56, Component TE-IS (80 mg trenbolone acetate, 16 mg estradiol, and 29 mg tylosin tartrate; Elanco US, Greenfield, IN) on d 112, and Component TE-S (200 mg progesterone, 20 mg estradiol benzoate, 29 mg tylosin tartrate; Elanco) on d 224. Steers in GRW/FIN were returned to WSBRC, weighed, and processed when they reached 312 ± 7.0 kg. Steers in GRW/FIN were implanted with Component TE-IS at the start of finishing, and Component TE-S on d 120. Steers in GRW/FIN were stepped up to the finishing diet when they reached 407 ± 6.0 kg. Finishing diets for the final 28 d for FIN and GRW/FIN included ractopamine hydrochloride at a rate of 300 mg·steer-1·d-1. At WSBRC, steers within each finishing system were sorted by BW into 4 to 5 head pens. Initial and terminal BW were greater (P < 0.01) in steers in the GRW/FIN finishing system. Body weight at reimplant was greater (P < 0.01) for FIN. Steers in the GRW/FIN system were on feed for fewer (P < 0.01) days compared with FIN steers. Average daily gain (ADG) and DMI (kg·steer-1·d-1) were greater (P < 0.01) for GRW/FIN. Steers in GRW/FIN had a greater (P < 0.02) feed:gain ratio than those placed directly into a finishing system. There were no differences (P < 0.10) in USDA Yield Grade, marbling, ribeye area (REA), or back-fat thickness (BFT) between finishing systems. Steers in FIN had a greater (P < 0.01) dressing percentage (DP) and lighter (P < 0.01) hot carcass weight than those for GRW/FIN. Finishing system has an impact on performance and efficiency of dairy-beef hybrid steers, but minimal impact on carcass quality.

PSVI-28 The Effects Supplementing Tannin Blend on Growth Performance, Energetic Efficiency, and Carcass Characteristics of Calf-Fed Steers

Abstract Objective of the current study was to evaluate the effects of tannin supplementation on cattle growth performance, energetic efficiency, and carcass characteristics of calf-fed steers. One hundred and sixty dairy steer calves with initial body weight (IBW) of 129.85 ± 3 kg, were blocked by IBW and randomly assigned to 40 pens (4 steers/pen; 10 pens per dietary treatment). Dietary treatments were: 1) Control (no additives); 2) MON (30 mg/kg monensin); 3) TAN (15 g/kg ByPRO; 70% condensed tannin; Silvateam USA, Tontitown, AR); and 4) MON+TAN (30 mg/kg monensin + 15 g/kg ByPRO). All steers were fed a similar steam-flaked corn-based diet (63.5% steam-flaked corn, 12.0% hay, 17.5% of dry distillers grains with solubles, 4.0% cane molasses, and 3.0% vitamin/mineral supplement). All cattle were slaughtered after 328 days of feed. There were no effects (P ≥ 0.13) of dietary treatment on final BW (615 ± 22 kg), overall average daily gain (1.48 ± 0.07 kg/day), overall dry matter intake (7.93 ± 0.39 kg/day), overall gain to feed ratio (0.187 ± 0.07), and overall observed vs. expected net energy for maintenance and gain (1.00 ± 0.03 and 1.00 ± 0.04, respectively). However, cattle receiving MON or MON+TAN supplementation increased (P ≤ 0.04) BW and gain to feed ratio in the first 112 days on feed compared with cattle in the control treatment. Moreover, cattle in the 2 dietary treatments receiving monensin supplementation tended (P ≤ 0.09) to increase average daily gain and gain to feed ratio on the first 112 days on feed compared with cattle in the control treatment. There were no effects (P ≥ 0.22) of feed additive supplementation on hot carcass weight (380.7 ± 14.7 kg), dressing percentage (61.83 ± 1.05%), kidney, pelvic, and heart fat (3.32 ± 0.19%), backfat thickness (0.73 ± 0.12 cm), longissimus muscle area (83 ± 4.83 cm2), marbling score (494 ± 48), and calculated yield grade (2.94 ± 0.24). Moreover, there were no effects (P ≥ 0.55) of dietary treatment on percent of liver abscess incidence, regardless of diet, calf-fed steers in the current study had 3.75% of liver with abscess.

29 The Role of Leptin and Its Regulation in the Hypothalamus of Neonatal Calves

Abstract The constant occurrence of increased feed intake in offspring exposed to intrauterine growth restriction has been noted across multiple species including ruminants. In ruminants, reduced circulating leptin concentrations from birth through the first week or two of life may influence the development of the appetite center of the hypothalamus. It should able be noted that increased circulating cortisol at birth has been associated with this decreased circulating leptin in the perinatal ruminants, yet information is limited as to any cause and effect relationship between the two hormones. The objectives of these studies were to test directly the effects of exogenous cortisol on leptin concentrations relative to development of the hypothalamus in perinatal calves and voluntary feed intake as yearling. In two experiments, Holstein bulls (n = 27) and calves (n = 32 males; n = 30 females) from commercial Angus cows were assigned to treatments at parturition (day 0). Calves were intravenously infused with either a low cortisol [LC; n = 9, 3.5 ug/kg of body weight (BW)], high cortisol (HC; n = 9, 7.0 ug/kg BW), or a control (CON; n = 9, saline). Calves were administered a half dose of their respective treatment 24h postpartum. Jugular vein blood samples were collected before infusion and daily until d 17 or necropsy. At 5 days of age Holstein bull calves were euthanized where cerebral-spinal fluid (CSF) and hypothalamic tissue were collected. Serum and CSF leptin concentrations were analyzed via RIA. Neuronal growth factors were analyzed in hypothalamus samples via qRT-PCR. In experiment 2, yearling calves entered a GROWSAFE System and daily feed intake (FI) measured. Animals were allowed a two-week adjustment period to a growing ration for heifers and a finishing ration for steers. Heifer body condition scores (BCS) were collected at the beginning and end of the trial. Heifers underwent the feeding trial for 70 days and steers until they obtained a back fat (BF) thickness of 1.15 cm. Blood samples were analyzed similar to experiment 1. All data were analyzed via repeated measures using appropriate models of SAS (SAS Institute Inc., Cary, NC). Perinatal dairy bull calves had decreased (P < 0.013) serum and CSF leptin concentrations of HC and LC calves compared with CON. Hypothalamic expression of BDNF, FGF1 and FGF2 were decreased (P < 0.006) in HC and LC compared with CON. During the feeding trial: BW gain, BCS change, and number of feed events were increased (P = 0.001) in LC compared with HC and CON heifers. However, LC observed greater daily FI (P = 0.047) and tended to have greater final BW (P = 0.080) compared with HC and CON steers. In summary, these data support that exogenous cortisol administered to perinatal calves affects leptin production and the appetite center of the hypothalamus when administered during the neonatal period.

123 Benchmarking of Artificial Neural Network Models for Genomic Prediction of Quantitative Traits in Pigs

Abstract Artificial neural networks (ANN) are a type of machine learning model that has been applied to various genomic problems, with the ability to learn non-linear relationships and model high-dimensional data. ANNs also have the potential in genomic prediction by capturing the intricate relationship between genetic variants and phenotypes. However, there is currently a limited effort to investigate the performance and feasibility of ANNs for pig genomic predictions. In this study, we evaluated the predictive performance of TensorFlow’s ANN models with one-layer, two-layer, and three-layer structures (with zero, one, and two hidden layers, respectively), in comparison with five linear methods, including GBLUP, LDAK, BayesR, SLEMM and scikit-learn’s ridge regression using data of six quantitative traits including off-test body weight (WT), off-test back fat thickness (BF), off-test loin muscle depth (MS), number of piglets born alive (NBA), number of piglets born dead (NBD), and number of piglets weaned (NW). Furthermore, we assessed the computational efficiency of ANNs on both CPU and GPU. The benchmarking was based on cross-validations of 26,190 genotyped pigs. We employed hyperband tuning to optimize the hyper-parameters and select the best model among one-layer, two-layer, and three-layer structures. Results showed that the one-layer structure, which is equivalent to ridge regression, yielded the best performance comparable to that of GBLUP. Using the optimal hyper-parameters for two-layer and three-layer structures, ANNs underperformed GBLUP in terms of accuracy. Of the five linear methods, BayesR and SLEMM performed similarly and the best, followed by LDAK, scikit-learn’s ridge regression, and GBLUP. Moreover, SLEMM was the fastest, which completed training with 21k individuals and 30k SNPs in 2.6 minutes. Compared with CPUs, GPUs exhibited a comparable computational speed for one-layer ANN but offered significant gains in computational efficiency for multi-layer ANNs. Based on our analysis of optimal hyper-parameters for two-layer ANN with BF, we found that using a GPU can lead to a five-fold increase in processing speed compared with using a conventional CPU, but it is still slower than GBLUP. In addition, hyper-parameter tuning (particularly for L2 regularization and the number of dense units in hidden layers) is critical for improving the genomic prediction accuracy in pigs. In conclusion, we found ANN with up to three layers could not improve genomic predictions compared with routine linear methods for pig quantitative traits.

218 Methane and Carbon Dioxide Emissions from Crossbred Beef Cattle Fall-Grazed on Native Aspen Parkland Pastures

Abstract Over 20 M ha of grazing land is utilized for beef production in western Canada, significantly contributing to the Canadian economy. Cattle are recognized for contributing to methane (CH4) and carbon dioxide (CO2), and individual animal contribution varies with several factors, one of them being feed efficiency as measured using residual feed intake adjusted for off-test backfat thickness (RFIfat). Given that commercial cattle spend a large portion of their production lifecycle grazing on diverse pastures in western Canada, understanding whether and how RFIfat measured in drylot and CH4 emissions reflect animal performance on pasture remains essential. This study quantified CH4 and CO2 production from beef cattle while grazing diverse diets on open-range aspen parkland pastures during fall. Cattle had been previously measured for RFIfat in drylot. Production of CH4 and CO2 (g/day) from crossbred beef cows (n = 22, with a range of -2.2 to +1.3 kg DM/day in RFIfat) and replacement heifers (n = 15; with a range of -2.6 to + 3.0 kg DM/day in RFIfat) were monitored using the GreenFeed emissions monitoring system over 40 days while grazing on native rangeland (70 ha) in the fall of 2022. Fall grazing was divided into two 20 ± 1 day' grazing periods; 20 days in September (SEP) vs. 20 days in October (OCT). Total spot measurements of CH4 and CO2 emissions in SEP and OCT were 1,096 vs. 1,054 for cows and 644 vs. 571 for heifers, respectively. The average number of daily visits per animal to the GreenFeed unit for cows and heifers were 2.8 ± 0.1 vs. 2.5 ± 0.1 in SEP, and 2.5 ± 0.1 vs. 2.0 ± 0.1 in OCT, respectively. Cows had greater average daily CH4 (SEP: 268.4 ± 6.1 vs. 196.1 ± 4.3; OCT: 243.9 ± 6.1 vs. 185.0 ± 4.3 g/day) and CO2 emission (SEP: 9,105.0 ± 143.1 vs. 6,485.3 ± 108.6; OCT: 8,544.3 ± 143.2 vs. 6,308.7 ± 108.9 g/day) than heifers (all P < 0.01). A negative relationship was evident between the CH4 emission and RFIfat in heifers (SEP: R2 = 0.043 vs. OCT: R2 = 0.014; P < 0.01), as well as CO2 emission and RFIfat (SEP: R2 = 0.083 vs. OCT: R2 = 0.020; P < 0.01), although the amount of variation explained by RFIfat is very small and is in disagreement with previous data. We speculate that the decline in CH4 and CO2 emissions from cattle in Oct might be due to various factors, including but not limited to changes in overall intake, daylight hours, air temperature, plant community, feeding and ruminating patterns, and rumen microbial profiles. Further analysis of forage quality, step counts, and GPS location, as well as rumen bacterial community, may shed more light on methane production in the fall.

Do carcass traits influence consumer perception of pork eating quality?

The objective of this study was to assess carcass traits' influence on pork eating quality as evaluated by consumers. A total of 1360 pork chops were used, with 824 from the sirloin end and 536 from the butt end of the loin (Longissimuss thoracis et lumborum), to produce 340 packages, each containing four pork chops. Untrained participants received one package of either sirloin or butt chops, being two pork chops from barrows and two from gilts. Participants answered a survey rating the tenderness, juiciness, flavour, and overall acceptability of each chop on an 8-point scale. Correlation analysis was conducted between carcass traits and pork eating quality attributes. For the descriptive analysis, classes (low, medium, and high) for carcass traits, Warner-Bratzler shear force (WBSF) and cooking loss were created based on our consumer responses dataset for palatability attributes. No significant correlations (P > 0.05) were observed between carcass traits and pork eating quality traits. Tenderness and overall acceptability were negatively correlated (P < 0.05) with cooking loss and WBSF. Loin intramuscular fat (IMF) content showed a weak negative correlation (P < 0.05) with WBSF and cooking loss. Consumers rated chops from the high and medium/high backfat thickness and loin IMF classes slightly higher for tenderness and juiciness, respectively. Additionally, chops from the low and/or medium WBSF and cooking loss classes received slightly higher scores for tenderness and juiciness than pork chops in the high classes. In conclusion, the study indicated that carcass traits had minimal impact on overall acceptability of pork by consumers.

Ultrasonographic image of fatty infiltration of the liver correlates with selected biochemical parameters and back fat thickness of periparturient Holstein-Friesian cows

Ultrasonographic image of fatty infiltration of the liver correlates with selected biochemical parameters and back fat thickness of periparturient Holstein-Friesian cows

Single-base editing in IGF2 improves meat production and intramuscular fat deposition in Liang Guang Small Spotted pigs

BackgroundChinese indigenous pigs are popular with consumers for their juiciness, flavour and meat quality, but they have lower meat production. Insulin-like growth factor 2 (IGF2) is a maternally imprinted growth factor that promotes skeletal muscle growth by regulating cell proliferation and differentiation. A single nucleotide polymorphism (SNP) within intron 3 of porcine IGF2 disrupts a binding site for the repressor, zinc finger BED-type containing 6 (ZBED6), leading to up-regulation of IGF2 and causing major effects on muscle growth, heart size, and backfat thickness. This favorable mutation is common in Western commercial pig populations, but absent in most Chinese indigenous pig breeds. To improve meat production of Chinese indigenous pigs, we used cytosine base editor 3 (CBE3) to introduce IGF2-intron3-C3071T mutation into porcine embryonic fibroblasts (PEFs) isolated from a male Liang Guang Small Spotted pig (LGSS), and single-cell clones harboring the desired mutation were selected for somatic cell nuclear transfer (SCNT) to generate the founder line of IGF2T/T pigs.ResultsWe found the heterozygous progeny IGF2C/T pigs exhibited enhanced expression of IGF2, increased lean meat by 18%–36%, enlarged loin muscle area by 3%–17%, improved intramuscular fat (IMF) content by 18%–39%, marbling score by 0.75–1, meat color score by 0.53–1.25, and reduced backfat thickness by 5%–16%. The enhanced accumulation of intramuscular fat in IGF2C/T pigs was identified to be regulated by the PI3K-AKT/AMPK pathway, which activated SREBP1 to promote adipogenesis.ConclusionsWe demonstrated the introduction of IGF2-intron3-C3071T in Chinese LGSS can improve both meat production and quality, and first identified the regulation of IMF deposition by IGF2 through SREBP1 via the PI3K-AKT/AMPK signaling pathways. Our study provides a further understanding of the biological functions of IGF2 and an example for improving porcine economic traits through precise base editing.

Effects of energy levels on growth performance, carcass characteristics, and fatty acid composition of Holstein steers at different slaughter ages.

We investigated the effect of energy levels on growth performance, carcass characteristics, and fatty acid composition of Holstein steers at different slaughter ages. Forty Holstein steers with an average body weight (BW) of 234.21 ± 7.42 kg and 7.78 ± 0.22 months were randomly allocated to two experimental groups; a 22-month-old experimental group and a 24-month-old experimental group. Total digestible nutrients (TDN) for each group were set to 70% (T1) and 72% (T2) during fattening phase and 74% (T3) and 76% (T4) for the finishing phase, respectively. No difference was observed in the final BW between the experimental groups during the fattening phase. However, in the finishing phase, the final BW of T4 (820.31 kg) group was significantly higher than that of T1 (745.57 kg; p < 0.05). The average daily gain (ADG) of T2 group in the finishing phase and overall period were 1.27 kg and 1.26 kg, respectively, which were significantly higher than those of T1 (1.11 kg and 1.12 kg; p < 0.05). The feed conversion ratio (FCR) and TDN conversion ratio of T2 group in the finishing phase also decreased by 10.23% and 7.73%, respectively, compared to those of T1. The cold carcass weight of T4 group was significantly higher (p < 0.05) than that of T1, whereas back fat thickness, longissimus area, and marbling score were not significantly different among groups. No differences were observed in physicochemical characteristics of the carcass including moisture, crude protein, and crude fat content among groups. However, the composition of fatty acids differed significantly between the groups. The content of C18:0 was significantly lower (p < 0.05) in T4 than in T1 group, and the content of C18:2 was higher in T4 than in T1 and T3 (p < 0.05). Therefore, feeding Holstein steers at a high-energy feeding level during the fattening and finishing phases improves ADG and reduces the slaughter age from 24 months to 22 months.

Effect of loading density and weather conditions on animal welfare and meat quality of slaughter pigs.

There are several factors that affect the welfare and meat quality of pigs during pre-slaughter transport. Among various factors, the effects of weather conditions and loading density were studied. A total of 3,726 finishing pigs were allotted to one of nine groups arranged in a 3 × 3 factorial design according to the weather conditions (low temperature [LT], under 10°C; normal temperature [NT], 10°C-24°C; high temperature [HT], upper 24°C), and loading density (low density [LD], upper 0.43 m2/100 kg; normal density [ND], 0.37-0.43 m2/100 kg; high density [HD], under 0.37 m2/100 kg). Each treatment group follow as: LTLD, LTND, LTHD, NTLD, NTND, NTHD, HTLD, HTND, HTHD. In terms of carcass composition, pigs had the highest carcass weight and backfat thickness at LT. Comparing the HD transport to the ND transport, the meat quality indicated a lower pH and more drip loss. The incidence rate of pale, soft, exudative (PSE) pork was high in the order of the HD, LD, and the ND transport (20%, 9%, and 2%, respectively). The HT transport showed the lowest pH and greatest L* value under the given weather conditions. Pigs transported under the HTHD and LTLD conditions had the greatest rates of PSE pork (40% and 20%, respectively). Pigs exposed to HD transport had the shortest laying time and the highest overplap behavior. The LDLT transport pigs had a shorter laying time than the LDNT and LDHT transport pigs. In conclusion, too high or too low density transport is generally not excellent for meat quality or animal welfare, however it is preferable to transport at a slightly low density at high temperature and at a slightly high density at low temperature.

Effects of lysine concentration of the diet on growth performance and meat quality in finishing pigs with high slaughter weights.

The present study aimed to investigate the feasibility of using a diet low in lysine content as a means for increasing the intramuscular fat (IMF) content and pork muscle quality of finishing pigs. Thirty-two crossbred gilts and barrows weighing approximately 80 kg were fed either a low-lysine diet (0.60%; Low-lys) or a control diet (0.80% lysine; Med-lys) under a 2 × 2 factorial arrangement of treatments. The animals were slaughtered at a 132-kg body weight (BW) on average, followed by physicochemical analyses and sensory evaluation on Longissimus lumborum (LL) and Semitendinosus (ST) muscles. The average daily gain (ADG) did not differ between the Med-lys and Low-lys groups. However, ADG exhibited a tendency of sex × diet interaction (p = 0.09), being greater for barrows vs. gilts on the Low-lys diet (p < 0.05), but not on the Med-lys diet. Backfat thickness adjusted for 132-kg BW also exhibited the interaction; it was greater for the Low-lys vs. Med-lys group within gilts but tended to be less for the former in barrows (p = 0.08). The IMF content was not influenced by the diet or sex in either LL or ST. The a*, b*, and Warner-Bratzler Shear Force values and fatty acid composition were influenced by the sex or diet in either or both of the muscles, but the treatment effects did not apparently influence the meat quality. Sensory scores for the flavor, juiciness, tenderness, umami, and palatability of cooked muscle were not influenced by the diet in either LL or ST. When the LL and ST data were pooled, scores for those sensory attributes were positively correlated with the IMF content, which was associated with overall greater IMF contents and greater sensory scores for ST vs. LL. Collectively, the Low-lysine diet seemingly elicited the intended lysine deficiency in gilts as indicated by the increased BFT due to the diet. However, the Low-lys diet was not effective for increasing the IMF deposition or eating quality of the pork muscle of finishing pigs slaughtered at high BW probably because its lysine content was not low enough to elicit either outcome.

Genetic Association Analysis of Copy Number Variations for Meat Quality in Beef Cattle.

Meat quality is an economically important trait for global food production. Copy number variations (CNVs) have been previously implicated in elucidating the genetic basis of complex traits. In this article, we detected a total of 112,198 CNVs and 10,102 CNV regions (CNVRs) based on the Bovine HD SNP array. Next, we performed a CNV-based genome-wide association analysis (GWAS) of six meat quality traits and identified 12 significant CNV segments corresponding to eight candidate genes, including PCDH15, CSMD3, etc. Using region-based association analysis, we further identified six CNV segments relevant to meat quality in beef cattle. Among these, TRIM77 and TRIM64 within CNVR4 on BTA29 were detected as candidate genes for backfat thickness (BFT). Notably, we identified a 34 kb duplication for meat color (MC) which was supported by read-depth signals, and this duplication was embedded within the keratin gene family including KRT4, KRT78, and KRT79. Our findings will help to dissect the genetic architecture of meat quality traits from the aspects of CNVs, and subsequently improve the selection process in breeding programs.

Loin Eye Muscle Ultrasonic Measurements, Live Weight and Some Body Measurements in Yalova Kıvırcık Lambs

Objective: This study was carried out to determine ultrasonic measurement parameters of the loin eye muscle characteristics, live weight and some body measurements in the marketing period of Yalova Kıvırcık lambs, and the relationships between them. Material and Methods: The research animal material consisted of 308 Yalova Kıvırcık lambs in 9 different farms under extensive conditions in Yalova province of Türkiye. Results: Least square means for backfat thickness (BFT), skin thickness, muscle depth (MD), body length (BL), chest girth (CG), and live weight (LW) at the mean age of 112 days were 0.20 cm, 0.15 cm, 1.94 cm, 60.50 cm, 73.82 cm, and 29.26 kg, respectively. Results of statistical analysis indicated that there was a significant difference between flocks in terms of MD, BFT, skin, BL, CG, and LW (P&amp;lt;0.001). The effect of gender was statistically significant on MD (P&amp;lt;0.05), BL (P&amp;lt;0.01), CG and LW (P&amp;lt;0.001). Conclusion: As a result, it was found that the MLD measurements, the live weight, and some body measurements in Yalova Kıvırcık lambs were similar to those in Kıvırcık breed and in some indigenous sheep breeds in Türkiye. Keywords: Loin eye muscle, carcass, backfat thickness, ultrasonic measurement, Yalova Kıvırcık

Genetic lines influenced the texture, collagen and intramuscular fat of pork longissimus and semimembranosus

The effects of genetic lines (PM-LR – Pure maternal, Landrace-type; PM-LW – Pure maternal, Large White-type; PM-D – Pure maternal, Duroc-type; SynT-LWLR – Synthetic terminal, Large white and Landrace-type; PT-D – Pure terminal, Duroc-type; and PT-LW – Pure terminal, Large White-type) on carcass traits and pork quality, including cooking loss, Warner-Bratzler shear force (WBSF), texture profile analysis (TPA), collagen content and solubility and intramuscular fat (IMF) content of Longissimus thoracis et lumborum (LTL) and Semimembranosus (SM), were investigated. The results showed that all terminal lines had lower backfat thickness than maternal lines, but muscles from line SynT-LWLR had the highest hardness and cohesiveness and the lowest IMF content. The SM showed higher hardness, adhesiveness, springiness, chewiness, collagen, and IMF content but lower WBSF and collagen solubility than LTL. Collagen and IMF content affected WBSF and TPA parameters across both muscles and in LTL alone. Significant relationships between collagen content and texture parameters were found in line PT-D. Genetic lines and muscles affect the contribution of collagen and IMF to pork texture.

179 Identification of Regulatory Mutations Affecting Complex Traits

Abstract Understanding genetic bases controlling complex traits of economic importance is fundamental to improve breeding programs. Recent efforts from FAANG consortium resulted in significant progress in the identification of regulatory regions in farm animals. However, most studies in cattle have focused on Bos taurus, and limited information is available for Bos indicus. Considering that Bos indicus is the predominant subspecies in tropical regions, the objective of this work was to identify regulatory variants associated with meat quality by combining information from whole genome sequence (WGS), gene expression (RNA-seq), and open chromatin regions (ATAC-seq). For genome wide association study (GWAS), an imputed panel of SNPs was obtained from WGS of 26 sires, a Bovine HD 770K panel of 374 progenies, and SNPs called from RNA-seq data of Longissimus thoracis muscle (LT) of 192 progenies. The SNPs were identified using GATK4, and the dataset included almost 4.5 million variants that were pruned to 553,581 tag-SNPs (PLINK, r2 = 0.8). ATAC-seq data was obtained from duplicated samples of LT collected from two animals. Phenotype data included back fat thickness (BFT), intramuscular fat (IMF), ribeye area (REA) and shear force (SF). Association of genotypes (553,581 SNPs) and gene expression (12,991 genes), performed in Matrix eQTL resulted in 36,916 cis-eQTL and 14,408 trans-eQTL (FDR &amp;lt; 0.05). For GWAS analysis of the eQTLs with phenotypic traits, we used a linear model in PLINK program (considering population stratification, contemporary group and hot carcass weight). GWAS resulted in 24 eQTLs associated with IMF, three with BFT, 12 with REA, and eight with SF (FDR &amp;lt; 0.10). ATAC-seq analysis (using nfcore/atacseq pipeline implemented in Nextflow) resulted in 33,734 consensus peaks with a mean size of 2.4 kb. The overlap analyses among GWAS, eQTL, and ATAC-seq positions resulted in two, four and one putative regulatory regions that control gene expression and are associated with BFT, IMF and SF, respectively. Functional studies are still necessary to establish if identified mutations are the causal mutation. In conclusion, integration of GWAS, RNAseq, and ATAC-Seq data can result in identification of regulatory mutations associated with phenotypes of economic importance.

189 The Effects of Dose Timing / Intervals on Grow-Finish Performance, Carcass Characteristics, Carcass Cutting Yields, and Meat Quality of Market Gilts Managed with Improvest

Abstract Improvest (Zoetis Canada Inc.) immunization provides temporary suppression of ovarian function and estrus in market gilts. The product requires two sequential injections administered at least 4 weeks apart, with full suppression of ovarian function demonstrated 4 to 10 weeks after the second injection. Recent research has shown the importance of closely monitoring the durations between the injections and between the second injection and slaughter. The objective was to determine the effects of dose timing and interval on grow-finish performance, carcass cutting yields, and meat quality of market gilts managed with Improvest when days on feed remained constant. The study consisted of 1,056 market gilts (average starting body weight of 31.7 kg) in 48 pens (22 pigs/pen) with experimental treatments arranged as a 2 × 2 factorial design with main effects of interval between the first and second Improvest injection (D1-D2; 4-week interval or 6-week interval) and time between the second Improvest injection and slaughter [D2-slaughter; weighted average of 34 to 35 days post-second injection (SHORT) or weighted average of 48 to 49 days post-second injection (LONG)]. Pigs were marketed using a similar strategy where the heaviest 3 to 5 pigs from each pen were marketed during study week 12, the next heaviest 3 to 5 pigs from each pen were marketed during study week 14, and the remaining pigs in the pen were marketed during study week 15. Hot carcass weight and optical probe readings (Destron PG-203; Anitech Identification System Inc.) were collected during slaughter. Following slaughter, 288 carcasses (24/treatment for each marketing event; pigs near the population average) were selected for evaluation of carcass cutting yields and meat quality. Data were analyzed with PROC MIXED of SAS, with pen serving as the experimental unit. There were limited interactions between D1-D2 and D2-slaughter, with nonsignificant interactions (P ≥ 0.07) for average daily feed intake (ADFI), average daily gain (ADG), and feed:gain (F:G) ratio during the grow-finish period, hot carcass weight, backfat thickness, or carcass primal weights. Overall, this study illustrated the trade-offs associated with altering the duration of time between D2-slaughter. From a live production standpoint, there were significant differences (P &amp;lt; 0.01) for D2-slaughter for ADFI and F:G ratio, with SHORT having reduced ADFI (2.47 kg versus 2.53 kg) and more efficient F:G (2.69 versus 2.74) compared with LONG (Table 1). From a meat processing standpoint, there were meaningful differences observed in fat deposition for D2-slaughter. In terms of fat quantity, backfat thickness and belly primal weight were affected (P &amp;lt; 0.01) by D2-slaughter (LONG had 0.78 mm greater backfat thickness and 0.15 kg heavier trimmed bellies). In terms of fat quality, iodine value and belly firmness were affected (P &amp;lt; 0.01) by D2-slaughter (LONG had 1.30 units lower iodine value and superior belly flop scores).

55 The Effects of Dietary Net Energy Levels on Grow-Finish Performance and Carcass Characteristics of Market Gilts Managed with Improvest

Abstract Improvest is a gonadotropin releasing factor (GnRF) analogue-diphtheria toxoid conjugate injection approved for temporary suppression of ovarian function and estrus in market gilts (Zoetis Canada Inc.). Study objectives were to determine the effects of three different net energy levels (LOW – 2.216 Mcal/kg, MID – 2.341 Mcal/kg, or HIGH – 2.466 Mcal/kg) during the grow-finish period on live performance and carcass characteristics of market gilts managed with Improvest (IMP) compared with market gilts not managed with Improvest (CON). The study consisted of 1,008 market gilts (average starting weight of 30.8 kg) in 48 pens (21 pigs/pen) with experimental treatments arranged as a 2 × 3 factorial design with main effects of Improvest (IMP or CON) and net energy level (LOW, MID, or HIGH). An equal number of pigs were marketed from each of the six treatment groups on day-83 (21.9% of the population), day-90 (21.9% of the population), day-97 (21.9% of the population), and day-104 (34.3% of the population) of the experiment. The weighted average for time post-second Improvest injection to marketing was 39.8 days. Data were analyzed with PROC MIXED of SAS, with pen serving as the experimental unit, fixed effects of Improvest (IMP or CON), net energy level (LOW, MID, or HIGH) and their interaction, and a random effect of pen location. There were no significant interactions (P ≥ 0.20) for average daily feed intake (ADFI), average daily gain (ADG), Feed:Gain (F:G), hot carcass weight (HCW), dressing percentage, backfat thickness, or predicted lean yield. However, IMP gilts consumed more feed (6.8% greater ADFI; P &amp;lt; 0.01), grew faster (5.0% greater ADG; P &amp;lt; 0.01), were less efficient (1.5% greater F:G; P &amp;lt; 0.01), were heavier (3.5 kg HCW; P &amp;lt; 0.01), and were fatter (1.9 mm greater backfat thickness and 0.9% less predicted lean yield; P &amp;lt; 0.01) than CON gilts. No difference (P = 0.21) in carcass dressing percentage between IMP and CON gilts was detected (Table 1). There were significant effects (P &amp;lt; 0.05) of net energy level for ADFI, ADG, F:G, HCW, and dressing percentage. Pigs fed LOW diets had the greatest ADFI, slightly less ADG, the least efficient F:G ratio, the lightest HCW, and reduced dressing percentage compared with HIGH (P &amp;lt; 0.01). There were no differences (P &amp;gt; 0.05) for backfat thickness or predicted lean yield among dietary energy level treatments. Overall, these data indicate that typical Improvest response levels were sustained at each of the net energy levels evaluated in this study (response levels for HCW of 2.6 kg for LOW, 3.4 kg for MID, and 4.5 kg for HIGH); however, consideration should still be provided to the known production impacts of low net energy diets when market gilts are managed with Improvest.

PSV-2 Impact of Diseases in Pig Production on Carcass and Meat Quality

Abstract Several diseases, including Porcine Respiratory and Reproductive Syndrome (PRRS), are present in pig herds. The effects of diseases on growth performance are generally well known, but there is a lack of information on the consequences on carcass and meat quality. The aim of this project was to assess the impact of diseases present in the nursery and finishing on performances, carcass yields and meat quality. The trial was carried out at the Deschambault Swine Evaluation Station, where a project aimed at evaluating disease resilience is being carried out. A total of 480 castrated piglets from 8 different batches entered the nursery barn every 3 weeks. Pigs were observed daily, and a careful examination of the clinical signs was carried out weekly on each animal, to separate pigs showing signs of disease from those in good health. Ultrasound measurements of back fat thickness, muscle depth and intramuscular fat (IMF) level were performed three different times during growth. When the pigs reached a body weight of approximately 120 kg, carcass quality and meat yield measurements were taken 18 to 24 hours after slaughter. The ultimate pH, color, water loss and marbling were measured on the loin. The presence of PRRS and other diseases had a significant impact on the growth performance of pigs in fattening and demonstrates that the presence of the virus in the herd significantly decreases the average daily gain (ADG). This difference has a direct impact on the number of days in fattening. Results for back fat thickness at the end of fattening show significant differences (P &amp;lt; 0.05) between uninfected pigs (14.7 mm), pigs infected in nursery (13.9 mm) and fattening (12.8 mm) only, and pigs that have been ill both in nursery and fattening (12.4 mm). These results indicate that the presence of diseases leads to a decrease in fat deposition in pigs at the end of fattening. However, results for IMF measured at the end of fattening demonstrate that the presence of diseases had no significant impact on the final IMF level (P &amp;gt; 0.10), varying between 2.05% for healthy pigs and 2.13% for animals that have been sick in nursery and fattening. The results obtained in the slaughterhouse have shown that the presence of diseases does not seem to have an impact on the various measures of meat quality (P &amp;gt; 0.05). Only drip loss shows a significant difference (P &amp;lt; 0.05) between healthy and sick animals. However, the low number of sick pigs in the batches evaluated could have limited the observed effects. The work carried out by the CDPQ has made it possible to quantify the impact of diseases by providing a better understanding of their impact on product quality.