Backfat Thickness Research Articles

Use of milk haptoglobin concentration as an indicator in animal health monitoring of dairy cows

The aim of the present study was to investigate relationships between elevated haptoglobin concentrations in milk and clinical as well as laboratory parameters in early lactating dairy cows. Furthermore, cut-off values should be identified for the differentiation of healthy and affected animals. 1462 dairy cows between 5.-65. days in milk were examined on 68 Bavarian farms. Milk and blood samples were taken once a week for a 7-week period per farm and body-condition-scoring, backfat thickness measurement and Metricheck examination, to evaluate uterine health, were performed. Milk samples were analysed for milk fat, milk protein, lactose, urea, ß-hydroxybutyrate and non-esterified fatty acids (indirect measurement, based on IR spectra), cell count, and milk haptoglobin. Blood samples were analysed for creatinine, aspartate aminotransferase, gamma-glutamyl transferase, glutamate dehydrogenase, total protein, albumin, creatine kinase, ß-hydroxybutyrate, non-esterified fatty acids, and blood haptoglobin.Cluster analyses were performed to determine cut-off values for haptoglobin. Besides milk haptoglobin (µg/ml) and blood haptoglobin (µg/ml), cell count (cells/ml milk), milk fat (%), milk protein (%), non-esterified fatty acids in blood (mmol/l), lactation number, days in milk, breed, season, and milk yield (kg) were included as significant input variables (p<0.005) in the cluster analyses. Cluster analysis, using k-means resp. k-prototypes algorithms, resulted in 5 (clusters 1-5 M1) resp. 4 different clusters (clusters 0-3 M2 and 0-3 B).A cut-off value of 0.5 µg/ml haptoglobin in milk was determined for the differentiation of healthy and affected animals. As milk is an easily available substrate, routine determination of haptoglobin in milk might be a suitable parameter for animal health monitoring. Using the detected cut-off value, apparently healthy animals with subclinical inflammatory diseases can be identified more quickly.

Genomic architecture of carcass and pork traits and their association with immune capacity

Carcass and pork traits have traditionally been considered of prime importance in pig breeding programmes. However, the changing conditions in modern farming, coupled with antimicrobial resistance issues, are raising the importance of health and robustness-related traits. Here, we explore the genetic architecture of carcass and pork traits and their relationship with immunity phenotypes in a commercial Duroc pig population. A total of nine traits related to fatness, lean content and meat pH were measured at slaughter (∼190 d of age) in 378 pigs previously phenotyped (∼70 d of age) for 36 immunity-related traits, including plasma concentrations of immunoglobulins, acute-phase proteins, leukocytes subpopulations and phagocytosis. Our study showed medium to high heritabilities and strong genetic correlations between fatness, lean content and meat pH at 24 h postmortem. Genetic correlations were found between carcass and pork traits and white blood cells. pH showed strong positive genetic correlations with leukocytes and eosinophils, and strong negative genetic correlations with haemoglobin, haematocrit and cytotoxic T cell proportion. In addition, genome-wide association studies (GWASs) pointed out four significantly associated genomic regions for lean meat percentages in different muscles, ham fat, backfat thickness, and semimembranosus pH at 24 h. The functional annotation of genes located in these regions reported a total of 14 candidate genes, with BGN, DPP10, LEPR, LEPROT, PDE4B and SLC6A8 being the strongest candidates. After performing an expression GWAS for the expression of these genes in muscle, two signals were detected in cis for the BGN and SLC6A8 genes. Our results indicate a genetic relationship between carcass fatness, lean content and meat pH with a variety of immunity-related traits that should be considered to improve immunocompetence without impairing production traits.

Genomic predictions and GWAS for heat tolerance in pigs based on reaction norm models with performance records and data from public weather stations considering alternative temperature thresholds.

Genetic improvement of livestock productivity has resulted in greater production of metabolic heat and potentially greater susceptibility to heat stress. Various studies have demonstrated that there is genetic variability for heat tolerance and genetic selection for more heat tolerant individuals is possible. The rate of genetic progress tends to be greater when genomic information is incorporated into the analyses as more accurate breeding values can be obtained for young individuals. Therefore, this study aimed (1) to evaluate the predictive ability of genomic breeding values for heat tolerance based on routinely recorded traits, and (2) to investigate the genetic background of heat tolerance based on single-step genome-wide association studies for economically important traits related to body composition, growth and reproduction in Large White pigs. Pedigree information was available for 265,943 animals and genotypes for 8686 animals. The studied traits included ultrasound backfat thickness (BFT), ultrasound muscle depth (MDP), piglet weaning weight (WW), off-test weight (OTW), interval between farrowing (IBF), total number of piglets born (TNB), number of piglets born alive (NBA), number of piglets born dead (NBD), number of piglets weaned (WN) and weaning-to-estrus interval (IWE). The number of phenotypic records ranged from 6059 (WN) to 172,984 (TNB). Single-step genomic reaction norm predictions were used to calculate the genomic estimated breeding values for each individual. Predictions of breeding values for the validation population individuals were compared between datasets containing phenotypic records measured in the whole range of temperatures (WR) and datasets containing only phenotypic records measured when the weather station temperature was above 10°C (10C) or 15°C (15C), to evaluate the usefulness of these datasets that may better reflect the within-barn temperature. The use of homogeneous or heterogeneous residual variance was found to be trait-dependent, where homogeneous variance presented the best fit for MDP, BFT, OTW, TNB, NBA, WN and IBF, while the other traits (WW and IWE) had better fit with heterogeneous variance. The average prediction accuracy, dispersion and bias values considering all traits for WR were 0.36 ± 0.05, -0.07 ± 0.13 and 0.76 ± 0.10, respectively; for 10C were 0.39 ± 0.02, -0.05 ± 0.07 and 0.81 ± 0.05, respectively; and for 15C were 0.32 ± 0.05, -0.05 ± 0.11 and 0.84 ± 0.10, respectively. Based on the studied traits, using phenotypic records collected when the outside temperature (from public weather stations) was above 10°C provided better predictions for most of the traits. Forty-three and 62 candidate genomic regions were associated with the intercept (overall performance level) and slope term (specific biological mechanisms related to environmental sensitivity), respectively. Our results contribute to improve genomic predictions using existing datasets and better understand the genetic background of heat tolerance in pigs. Furthermore, the genomic regions and candidate genes identified will contribute to future genomic studies and breeding applications.

The effect of tissue mobilization and stage of lactation on energy partitioning in lactating sows: an analysis of commercial data

AbstractThe objective of this paper was to investigate how the predicted level of body energy mobilized and the stage of lactation affects performance and energy partitioning in lactating sows kept under commercial conditions. Seventy-seven lactating sows from three consecutive batches were weaned at 28 d and all measures were taken over the first 20 d. Total feed consumption was measured and sows’ live weight was registered when entering the lactation facilities and at 21 d of lactation. Blood samples were collected at farrowing and once a week thereafter. Net energy (NE) mobilization or loss was calculated by difference using the general NRC equation for ME partitioning. Compared to low mobilizers (low NE loss values), high mobilizing sows had lower feed intake and higher loss of live weight, body fat and body protein. High mobilizers also weaned more piglets and had heavier litters than low mobilizers. Energy mobilization (NE loss) was higher from day 1 to 10 of lactation compared to day 11 to 20, and the difference in mobilized energy between high and low mobilizing sows was also higher in the first than in the second half of lactation. Body weight and back fat thickness losses were significantly correlated with NE loss. A more accurate prediction of the changes in live weight or back fat thickness over lactation should help better predict total amount of energy mobilized, and more research is needed to assess the relative contribution of lean and fat to mobilized tissue.

Effect of protein-restricted diet during growing period on performance and carcass quality traits of Duroc x Iberian crossbred barrows under different management conditions

This study investigated the effects of feeding protein-restricted diets during the growing period on performance and carcass quality traits of Duroc (boars) x Iberian (sows) crossbred pigs slaughtered at commercial weight for local pig production. Two trials were conducted in different management conditions, with 28 and 33 barrows, respectively. In each trial, pigs were divided into two dietary groups, one group received a control diet (CD, 16.5 % crude protein, CP) and the other one was fed a protein restricted diet (PRD_1 for Trial 1: 12.4 % CP; and PRD_2 for Trial 2: 10.0 % CP). At 100 kg of body weight (BW), five pigs per group and trial were slaughtered, while the remaining pigs were fattened on a standard finishing diet until reaching 160 kg BW before slaughter. No significant changes in growth, carcass and ham composition or backfat thickness due to decreased protein supply during the growing period were observed. However, the intramuscular fat content increased in Longissimus thoracis et lumborum (LTL) and ham muscles of PDR_2 pigs. Furthermore, the backfat fatty acid (FA) profile presented higher proportion of oleic and monounsaturated FAs in pigs fed PRD diets, while polyunsaturated FA decreased in PDR_2 pigs. The PRD_1 group exhibited higher redness and thawing water loss in LTL, while PDR_2 group showed greater redness, yellowness and thawing water loss values compared to the CD group. Overall, the results indicate that feeding protein-restricted diets during growing period did not have a substantial impact on growth or meat quality. The success of implementing such diets may be influenced by factors such as the protein restriction level and the animal management conditions.

The effect of dietary omega-3 fatty acid supplementation on fetal growth, piglet birth weight and plasma fatty acid concentrations, using docosahexaenoic acid in early gestation in sows

The objective of the study was to test the effect of the omega-3 fatty acid docosahexaenoic acid (DHA) on fetal and placental development as well as the birth weight of piglets. A total of 238 multiparous sows were allocated to either a control diet group or a DHA diet group with an omega-6 to omega-3 ratio of 9.8 and 2.4, respectively, from mating to day 43 of gestation. A blood sample was collected and back fat thickness was measured prior to mating, on days 14, 42 and 112 of gestation. On day 43 of gestation, 14 sows were slaughtered and measurements of fetuses and placentas were taken. Piglets in some litters were weighed individually at farrowing. Dietary treatment did not affect fetal characteristics and back fat thickness (P > 0.05). Dietary treatment increased the plasma concentrations of total omega-3 fatty acids in sows (P < 0.05). Sows fed the DHA diet had a shorter gestation length compared to the control sows (P < 0.05), but the number of born piglets was not affected (P > 0.05). The average piglet birth weight and the within-litter variation in birthweight were unaffected by dietary DHA (P > 0.05), however, sows fed DHA diet had fewer piglets under 800 g at birth compared to control sows (P < 0.05). In conclusion, addition of DHA decreased the dietary ratio of omega-6 to omega-3 fatty acids, increased plasma n-3 fatty acid concentrations in sows and decreased the number of piglets weighing under 800 g at birth.

Cloning and functional characterization of porcine AACS revealing the regulative roles for fat deposition in pigs.

Fat deposition is a quantitative trait controlled by multiple genes in pigs. Using transcriptome sequencing, we previously reported that AACS is differentially expressed in the subcutaneous fat tissue of Dingyuan pigs with divergent backfat thickness. Therefore, with the aim of further characterizing this gene and its protein, we cloned the entire 3286-bp mRNA sequence of the porcine AACS, and the encoded AACS protein is a hydrophilic protein without a signal peptide or transmembrane sequence. Our findings suggested that among various tissues and pig breeds, AACS was highly expressed in subcutaneous fat. We have identified three completely linked SNP loci in the AACS gene: A-1759C, C-1683T, and A-1664G. The double luciferase activity test in the 5' flanking region indicated that the flanking region of AACS contained several active regulatory elements. The three linked SNPs that were identified in one of the critical active elements, and might serve as important molecular markers regulating backfat thickness. Finally, we observed that AACS overexpression inhibited the proliferation and differentiation of subcutaneous preadipocytes. Collectively, our results suggest that AACS inhibits subcutaneous fat deposition in pigs. This study provides a new molecular marker for understanding the mechanism of porcine fat deposition.

Development and validation of a fully automated 2-dimensional imaging system generating body condition scores for dairy cows using machine learning

Monitoring body condition score (BCS) is a useful management tool to estimate the energy reserves of an individual cow or a group of cows. The aim of this study was to develop and evaluate the performance of a fully automated 2-dimensional imaging system using a machine learning algorithm to generate real-time BCS for dairy cows. Two separate datasets were used for training and testing. The training dataset included 34,150 manual BCS (MAN_BCS) assigned by 5 experienced veterinarians during 35 visits at 7 dairy farms. Ordinal regression methods and deep learning architecture were used when developing the algorithm. Subsequently, the testing dataset was used to evaluate the developed BCS prediction algorithm on 4 of the participating farms. An experienced human assessor (HA1) visited these farms and performed 8 whole-milking-herd BCS sessions. Each farm was visited twice, allowing for 30 d (±2 d) to pass between visits. The MAN_BCS assigned by HA1 were considered the ground truth data. At the end of the validation study, MAN_BCS were merged with the stored automated BCS (AI_BCS), resulting in a testing dataset of 9,657 single BCS. A total of 3,817 cows in the testing dataset were scored twice 30 d (±2 d) apart, and the change in their BCS (ΔBCS) was calculated. A subset of cows at one farm were scored twice on consecutive days to evaluate the within-observer agreement of both the human assessor and the system. The manual BCS of 2 more assessors (HA2 and HA3) were used to assess the interobserver agreement between humans. Finally, we also collected ultrasound measurements of backfat thickness (BFT) from 111 randomly selected cows with available MAN_BCS and AI_BCS. Using the testing dataset, intra- and interobserver agreement for single BCS and ΔBCS were estimated by calculating the simple percentage agreement (PA) at 3 error levels and the weighted kappa (κw) for the exact agreement. A Bland-Altman plot was constructed to visualize the systematic and proportional bias. The association between MAN_BCS and AI_BCS and the BFT was assessed with Passing-Bablok regressions. The system had an almost perfect repeatability with a κw of 0.99. The agreement between MAN_BCS and AI_BCS was substantial, with an overall κw of 0.69. The overall PA at the exact, ± 0.25-unit, and ± 0.50-unit BCS error range between MAN_BCS and AI_BCS was 44.4%, 84.6%, and 94.8%, respectively, and greater than the PA obtained between HA1 and HA3. The Bland-Altman plot revealed a minimal systematic bias of -0.09 with a proportional bias at the extreme scores. Furthermore, despite the low κw of 0.20, the overall PA at the exact and ± 0.25-unit of BCS error range between MAN_BCS and AI_BCS regarding the ΔBCS was 45.7 and 88.2%, respectively. A strong linear relationship was observed between BFT and AI_BCS (ρ = 0.75), although weaker than that between BFT and MAN_BCS (ρ = 0.91). The system was able to predict single BCS and ΔBCS with satisfactory accuracy, comparable to that obtained between trained human scorers.

Association analysis of mitochondrial genome polymorphisms with backfat thickness in pigs

Mitochondrial DNA (mtDNA) variations and associated effects on economic traits have been widely reported in farm animals, as these genetic polymorphisms can affect the efficiency of energy production and cell metabolism. In studies related to metabolism, the deposition of fat was highly correlated with mitochondria. However, the effect of mtDNA polymorphisms on porcine backfat thickness (BFT) remained unclear. In this study, 243 pigs were collected to analyse the relationship between BFT and mtDNA polymorphisms. There were considerable differences in BFT, ranging from 5 mm to 18 mm. MtDNA D-loop sequencing discovered 48 polymorphic sites. Association analysis revealed that 30 variations were associated with BFT (P < 0.05). The polymorphism m.794A > G showed the maximum difference in BFT between A and G carriers, which differed at ∼2.5 mm (P < 0.001). The 48 polymorphic sites generated 22 haplotypes (H1-H22), which clustered into 4 haplogroups (HG1-HG4). HG1 had a lower BFT value than other three haplogroups (P < 0.01), whereas H4 in HG1 exhibited the lowest BFT of all haplotypes analyzed (P < 0.01). The results of this study highlight an association between mtDNA polymorphisms and BFT, and suggest the potential application of mtDNA in pig molecular breeding practices.

The Effect of Replacing Whole-Plant Corn Silage with Daylily on the Growth Performance, Slaughtering Performance, Muscle Amino Acid Composition, and Blood Composition of Tan Sheep.

The shortage of high-quality coarse feed resources is the main factor that restricts the development of animal husbandry in many developing countries. The present study aimed to investigate the effects of replacing corn silage with daylily silage on the growth performance, slaughter performance, blood biochemical indicators, meat quality, and muscle amino acid composition of Tan sheep. A total of 72 healthy Tan sheep were randomly assigned to four groups. In each group, 0%, 20%, 40%, and 60% of corn silage were replaced with daylily silage (denoted as CON, HC20, HC40, and HC60, respectively). Tan sheep fed with daylily silage showed no significant adverse effects on their growth performance, meat quality, and muscle amino acid composition (p > 0.05). Some increase was observed in the carcass fat content value (GR-value, p < 0.05), thickness of backfat (p < 0.05), and the blood urea level (p < 0.05). These findings indicate that the utilization of daylily silage instead of whole-plant corn silage has no adverse effects on the growth performance and meat quality of Tan sheep, thus indicating that it can partially replace whole-plant corn feed as a feed resource for Tan sheep.

PSXII-16 Evaluation of a Grade Ruler Approach for Yield Grading of Veal Carcasses

Abstract Introduction: yield estimations in carcass grading systems are important for the meat industry to assign value and sort carcasses for different market specifications. Previous studies in different species have reported yield estimations performed using anatomical linear measurements that segregate carcasses into grades or classes. However, veal carcasses are not currently segregated in terms of carcass yield performance and the Canadian veal industry is now discussing the option of implementing yield assessments for veal carcass grading purposes. The aim of the present study was to evaluate the feasibility of a grade ruler approach to predict yield performance of veal carcasses for grading purposes. A total of ~300 (males and females) veal carcass sides representative of the current Canadian veal population (body weight: 127.5 to 189.2 kg; backfat: 0.5 to 20.7 mm) were use in the present study. Carcass sides were scanned using a Lunar iDXA unit to evaluate the content of total fat, lean and bone. Results and discussion: total carcass lean was mainly correlated with the hot carcass weight (r = 0.65), ¼ backfat thickness (r = -0.33) and rib eye area (REA: r = 0.58) at the 11th – 12th rib-eye location (P &amp;lt; 0.05). Because the time to grade veal carcasses at the grading stand is limited and the efficiency of the grading tools (e.g., ruler) has to be maximized, the ¼ backfat thickness and the width and length of the ribeye were the main factors considered to develop a prediction equation. These continues variables (backfat thickness and REA) were then categorized assigning fat classes (1-10) in 2 mm increments and 4 muscle scores (small-large). The new equation developed for the estimation of lean yield incorporating the anatomical traits of muscle score and fat class showed a R2 of 0.62 and a root mean square error of 2.14 %. Based on this equation, a matrix of estimated lean meat yield percentage using the fat class and muscle score descriptors (Table 1) was developed for the implementation in a yield ruler. The results of the present study suggest that lean yield percentage from veal carcasses might be objectively and accurately predicted applying a yield ruler approach. This tool will facilitate the veal yield grading by just determining the fat class (at ¼ backfat thickness) and muscle score at the 11th – 12th rib location.

PSV-23 Characterization of Katahdin Lamb Carcasses in a Traditional Lamb Marketing Context

Abstract The Katahdin breed has grown in popularity in the US, but it is relatively unknown if their carcasses conform to expectations of the traditional commodity lamb industry. Purebred Katahdin wethers (n = 223) were sourced from the genetic reference flock at the U.S. Meat Animal Research Center over two consecutive years. The flock is enrolled in the National Sheep Improvement Program (NSIP) and estimated breeding values (EBV) were available on standard production traits. Lambs were assigned to one of three groups per year based on body weight (BW) and fed a common finishing diet through harvest at similar end BW (51.3 ± 5.6 kg) but varying age (223.8 ± 32.2 d). Lambs were harvested at a commercial processor, hot carcass weight (HCW) was recorded, dressing percentage (DP) was calculated, and carcasses were chilled for 24 h. Carcasses were then ribbed and 12th rib backfat thickness (BFT), and loin muscle area (LMA) were measured. Traits were analyzed in mixed models with fixed class effects of finishing group (6 levels) and rearing type (single or multiple), a linear covariate of harvest age, and a random effect of sire (n = 16). There were no differences in BW, HCW, BFT, and LMA between rearing types but lambs reared as multiples had greater DP than those reared as singles (P = 0.02; Table). End BW increased while DP decreased with lamb harvest age (P ≤ 0.03). Pearson correlation coefficients were estimated between traits including post-weaning weight (PWWT) NSIP EBV. There was a strong, positive correlation between HCW and BFT (0.52) and HCW and BWT (0.54; P &amp;lt; 0.001). In contrast, HCW was only moderately correlated to LMA (0.35; P &amp;lt; 0.001). The PWWT EBV is the best genetic predictor of post-weaning lamb growth and was moderately correlated with end BW (0.38), HCW (0.35), and LMA (0.35; P &amp;lt; 0.001). Traditional markets prefer carcasses to be 29.5 – 36.3 kg HCW and &amp;lt; 6.4 mm BFT; 91% and 51% of Katahdin carcasses were below the HCW and BFT thresholds, respectively. Katahdins are capable of producing lean carcasses that conform to packer ideals for BF when fed to harvest BW of the present study, which may reduce excess fat trimming during fabrication. However, HCW observed in the present study may suggest greater suitability for non-traditional (i.e., ethnic) markets. Lower correlations between carcass traits in Katahdin compared with past research in Western white-faced lambs may highlight important biological differences in growth and fat deposition among divergent breed types. Crossbreeding Katahdin ewes with terminal sire breeds and within breed selection will improve growth and carcass traits without exceeding HCW thresholds commonly reached in wool sheep but should be considered in tandem with other breeding objectives.

PSXIV-26 Live Animal Longissimus Thoracis Mitochondrial Capacities at 10, 13, and 18 Months of Age Are Related to Meat Quality in Angus and Brahman Steers

Abstract Mitochondrial abundance and efficiency correlate with meat color, but relationships between live animal mitochondria and other markers of beef quality remain largely unknown. To test the hypothesis that live animal skeletal muscle mitochondrial markers would be correlated with post-harvest hot carcass weight, ribeye area, calculated yield grade, backfat thickness, and marbling, samples were collected from the longissimus thoracis of Brahman and Angus steers at 10 mo (25 Angus, 23 Brahman), 13 mo (35 Angus, 33 Brahman), and 18 mo (35 Angus, 33 Brahman) of age. Mitochondrial volume density and function were quantified by citrate synthase (CS) and cytochrome c oxidase activities, respectively. Mitochondrial oxidative phosphorylation (OxP) and electron transfer (E) capacities were determined via high-resolution respirometry. Relationships between mitochondrial variables and carcass quality were determined using PROC CORR in SAS (v9.4). Within Angus at 10 mo, integrative (per mg tissue) complex I-supported OxP (PCI), maximal OxP (PCI+II), maximal E (ECI+II), and E supported by complex II (ECII) were positively correlated with hot carcass weight (P ≤ 0.05). Also, within 10 mo Angus, integrative OxPCI and flux control ratio (FCR) for OxPCI were positively correlated with backfat thickness (P ≤ 0.03). Within 10 mo Brahman, integrative PCI was positively correlated with ribeye area (P = 0.04). Within 13 mo Brahman, integrative mitochondrial proton LEAK was positively correlated with hot carcass weight (P = 0.02) and intrinsic (relative to CS activity) LEAK, PCI, and ECI+II were positively correlated with marbling (P ≤ 0.05). Conversely, CS activity was negatively correlated with marbling in 13 mo Brahman (P = 0.05). Integrative, FCR, and intrinsic LEAK were negatively correlated with ribeye area (P ≤ 0.05) but positively correlated with calculated yield grade in 13 mo Angus (P ≤ 0.03). However, at 18 mo, integrative, FCR, and intrinsic LEAK were positively correlated with ribeye area (P ≤ 0.008) but negatively correlated with calculated yield grade (P ≤ 0.01) in Angus steers. Furthermore, integrative and intrinsic OxPCI+II, ECI+II, and ECII were positively correlated with marbling in 18 mo Angus (P ≤ 0.04). Within 18 mo Brahman, CS activity was positively correlated with ribeye area (P = 0.006). Cytochrome c oxidase activity was not correlated with any markers of meat quality. These results suggest that mitochondrial capacity for energy production in Angus and Brahman steers at different life and production stages may dictate potential for skeletal muscle growth and lipid metabolism leading to differences in beef quality at slaughter. This project was supported by USDA NIFA Award #2021-67015-33392.

320 Effects of Sorting Strategy on Within-Pen Variation and Profitability

Abstract Decreasing variation in a pen of feedlot cattle reduces overfeeding, increases carcass quality and uniformity, and improves economic returns. The objective of this study was to evaluate the effect of sorting by body weight (BW) or expected days on feed (DOF) on pen performance and profitability. Ninety-six Angus-cross steers (initial BW = 360 ± 28 kg) were randomly assigned to sorting by BW or DOF determined using the Davis Growth Model and initial body measurements for BW, hip height, back fat thickness (BF), and ribeye area. Steers within BW and DOF sort groups were randomly assigned to one of two replicates. Within replicate, BW groups were divided into light and heavy pens (initial BW = 323 and 366 kg, respectively), and DOF groups were divided into short and long pens (DOF = 119 and 160 d, respectively), for a total of 8 pens with 12 steers in each pen. Pen feeding was managed using the slick bunk method and time of marketing was determined based on observation of an average pen BF of 1.1 cm. Steers were harvested at a commercial abattoir and individual carcass characteristics were recorded. Profit was calculated as carcass value minus feed costs. For comparison of sorting treatments, pen was the experimental unit, and treatment means and variances were compared using a t-test and F-test, respectively. Steers were harvested in three groups: both heavy-BW sort pens and both short-DOF sort pens were harvested after 84 d, both long-DOF sort pens and one light-BW sort pen were harvested after 104 d, and the final light-BW sort pen was harvested after 116 d on the finishing ration. There were no differences in mean initial BW (P = 0.95) or initial percent empty body fat (EBF; P = 0.28), but variation in initial BW was reduced (P &amp;lt; 0.01) for the BW sort group. Final mean BW did not differ between sort groups (P = 0.54), but variance in final BW and hot carcass weight was less (P &amp;lt; 0.01) for the group sorted by BW. Final percent EBF also did not differ between groups (P = 0.41), but percent EBF variance was 2.4 %-units for DOF and 2.9 %-units for BW sorted pens, although differences were not statistically significant. There were no differences in average daily gain or feed conversion rate between sort groups. Variation in yield grade, BF, and marbling score were numerically reduced for the DOF group; however, differences were not statistically significant (P &amp;gt; 0.10). Average profit per steer was $ 321.42 and $ 235.05 for DOF and BW sorted groups, respectively. Sorting by DOF increased profitability by 26% by increasing harvest BW, improving uniformity, and decreasing overweight carcasses.

82 Critical Comparison of Water Buffalo (Bubalus bubalis) and Cattle on Growth Performance and Carcass Traits: a Review

Abstract The multipurpose water buffalo (Bubalus bubalis) has been exploited mostly for dairy purposes while being poorly utilized for meat production. However, in the marketplace, a prejudice exists against Buffalo carcasses due to most of the carcasses coming from animals at the end of their productive life on the dairy farm. Unfortunately, scarce literature establishes comparative biological endpoints between water buffaloes and cattle (Bos indicus or Bos taurus) as meat producers. Furthermore, the literature has not considered the effects of gender (i.e., male castration) for any interspecific comparison. Many unknown answers remain regarding Buffalo growth performance, carcass traits and composition with respect to cattle. Therefore, this review will discuss the pros and cons of water buffalo meat production with respect to cattle, particularly research carried out in tropical conditions, regarding the production traits indicated previously. In a few studies, water buffaloes have proven to be adaptable to tropical grazing conditions and have shown consistently faster body weight gains; but, under confinement conditions, water buffalo have shown a slower growth rate performance than cattle, requiring more days than cattle to reach a comparable body weight. Water buffaloes present heavier carcasses but ldecreased dressing percentages than cattle at different ages which are explained by their significantly greater body proportions of the head, hide and internal organs at the post-weaning ages than cattle. Additionally, under similar grazing or confinement conditions, water buffalo had abundant fat cover distribution and back fat thickness than cattle. Consequently, their carcasses yielded greater percentages of trimmed fat, with a reduced proportion of total cuts. Based on the observed growth and carcass traits, water buffalo offers a promising alternative for meat production, a specialty under tropical grazing conditions.

32 Feeding Gilts and Sows to Maximize Their Mammary Development

Abstract The task of feeding growing replacement gilts, gestating gilts and sows to maximize their future milk yield is not easy. Yet, this is particularly important when considering the great demands made by the large litters of our current hyperprolific sow genetic lines. One aspect that needs to be considered is the effect of feeding on mammary development taking place before the onset of lactation, which is a major determinant of potential milk yield. One can only attempt to stimulate mammogenesis during periods with rapid mammary development. In swine, these periods are from three months of age until puberty, from 90 days of gestation until farrowing, and throughout lactation. Early studies showed that a 20% or 26% feed restriction from 90 days of age until puberty drastically reduces mammary parenchymal tissue mass. However, in a more recent study, sow milk yield was not altered following a 10% or 20% feed restriction, or a 25% dietary fiber addition (diluting dietary energy by 5%) from 90 days of age to breeding. This absence of effect may be due to the greater feed intake of control gilts in that recent study compared with the older studies. Such a difference in feed intake was likely brought about by genetic selection for faster growing pigs, and it appeared that feed intake of growing gilts can be reduced to 2.7 kg/day without detrimental effects on their future milk yield. During prepuberty, inclusion of the phytoestrogen genistein (2.3 g/day) in the diet increases the number of mammary parenchymal cells. During late gestation, feeding very high energy levels (10.5 Mcal ME/day) may have detrimental effects on mammary development and subsequent milk production. Furthermore, feed intake throughout gestation is important because of its effect on body condition. Gilts that are too thin (&amp;lt; 16 mm backfat thickness) in late gestation have reduced mammary development. A 40% increase in SID Lys via inclusion of additional soybean meal to the diet of gilts from days 90 to 110 of gestation increased mammary parenchymal mass by 44%. On the other hand, providing the same 40% increase in dietary SID Lys to multiparous sows during late gestation had no significant effect on mammary parenchymal mass. These findings therefore support the use of phase-feeding during gestation of gilts only. Increasing circulating concentrations of the growth factor IGF-1 during late gestation also increased mammary parenchymal mass by 22%. Current data clearly demonstrate that feeding management before lactation can be used to improve sow milk yield.

215 Optimizing the Standardized Ileal Digestible Lys-To-Net Energy Ratio for Nitrogen Utilization of Sows Throughout a 24-Day Lactation Period

Abstract Fifty multiparous sows (average parity 3.7±0.9 and initial BW 245.6±32.5 kg) were used to evaluate the effects of dietary standardized ileal digestible (SID) Lys-to-net energy (NE) ratios on nitrogen utilization throughout a 24-day lactation period. Sows were randomly assigned to one of five isoenergetic feeding programs that provided equally spaced and increasing Lys-to-NE ratios between 2.79 and 5.50 g SID Lys/Mcal NE. The feeding programs were generated by blending the two extreme diets in varying proportions using a precision feeding system and were provided to sows immediately after farrowing (d1) and until weaning at d 24 ± 1. At farrowing, litters were standardized to 12 piglets. Three nitrogen balances were conducted from d 4 to 7±1 (NB1), 12 to 15 ± 1 (NB2), and 20 to 23 ± 1 (NB3) using total urine collection and fecal grab sampling. Contrast statements were used to determine linear and quadratic effects of increasing Lys-to-NE ratios. Linear (LBL) and quadratic (QBL) broken-line and polynomial quadratic (QPM) models were used to determine the optimum dietary Lys-to-NE ratios for N retention. The Bayesian information criterion was used to assess best fit. Feeding program did not influence sow ADFI (5.96 ± 0.19 kg/d), BW change (-5.4 ± 4.1 kg) or change in backfat thickness (-2.0 ± 1.1 mm) over the entire 24-d lactation period, but piglet ADG increased with dietary Lys-to-NE ratio (linear; P &amp;lt; 0.05). Sow N intake increased with dietary Lys-to-NE ratio in NB2 and NB3 (linear; P&amp;lt; 0.001). Nitrogen retention (N intake – N output in urine and feces) increased with dietary Lys-to-NE ratio in all NB (linear; P = 0.05, P &amp;lt; 0.001, and P &amp;lt; 0.001 for NB1 -to 3, respectively). The QPM showed an inflection point at 3.75 g Lys/Mcal NE during NB1 and the QBL model showed break points at 2.87 and 4.83 g Lys/Mcal NE in NB2 and NB3, respectively. Nitrogen retention in milk increased with dietary Lys-to-NE ratio only in NB1 (linear; P &amp;lt; 0.05) and the QPM showed inflection points at 4.31, 4.37, and 4.90 g Lys/Mcal NE for NB1-to-3, respectively. Maternal nitrogen retention (N intake – N output in urine, feces, and milk) decreased and then increased in NB1 (quadratic; P &amp;lt; 0.01) and increased in NB2 and NB3 (linear; P &amp;lt; 0.01) with dietary Lys-to-NE ratio. The QPM showed inflection points at 4.01 and 3.01 g Lys/Mcal NE for NB1 and NB2, respectively, and the QBL model showed a breakpoint at 4.83 g Lys/Mcal NE for NB3. To optimize N retention, feeding programs with a Lys-to-NE ratio between 3.75 and 4.31, 2.87 and 4.37, and 4.83 and 4.90 g SID Lys/Mcal NE should be considered during early, mid, and peak lactation, respectively. Therefore, precision feeding programs can be developed to match the ideal SID Lys-to-NE ratio more closely at different stages of lactation to improve sow performance and reduce nitrogen excretion to the environment.

PSXI-14 Effect of a Sensory Additive to Maximize Sow Feed Intake and Performance of Piglets During Lactation Under Heat Stress Conditions

Abstract Longevity of the sows is a major concern in pig production, which is negatively affected when the sow body condition is not properly restored shortly after weaning. Therefore, feed intake (FI) becomes crucial to prevent the excessive body reserve mobilization during lactation, but also in promoting milk production and therefore maximizing litter performance. This situation is more exacerbated under heat stress conditions, in which FI is severely affected. The aim of the present study was to increase the sow FI and to maximize litter performance during lactation under heat stress conditions. A total of 20 Landrace x Large White sows were used. Animals were individually caged in farrowing crates one week before parturition according to their body weight, backfat thickness and parity and randomly assigned to two treatments (10 sows/treatment): Control diet, (C) or a diet containing a sensory additive (SA) included at 0.075% (Luctamax Sows, Lucta S.A., Barcelona, Spain). All diets were offered restricted from entry to the farrowing unit until parturition and ad libitum afterwards until weaning. For the sows’ body weight (BW, kg) a scale was used; back fat (BF, mm) was registered by ultrasound echography (in mm). Both measurements were performed at the entry to the farrowing unit and at weaning. Piglets’ performance was also monitored from birth to weaning (21 d of life). Higher temperature during the trial was over 30ºC (reaching a maximum of 37ºC). Data were analyzed by using the TTEST procedure of SAS. Results showed that SA sows increased up to 6.2% their FI compared with the C group (5.86 kg/d vs 5.52 kg/d, P = 0.08) from farrowing to weaning. Regarding the body reserves mobilization, BW (-24.7 kg vs -29.4 kg) and BF (-1.00 mm vs -3.30 mm) loses were numerically less in SA sows compared with C sows, respectively (P &amp;gt; 0.05). Finally, concerning performance of piglets, the inclusion of the SA tended to increase the growth during the first week after farrowing (0.174 kg/d vs 0.156 kg/d, P = 0.06) compared with the C group, respectively with no significant differences for the whole lactation period. Similarly, piglets weaning BW was slightly numerically greater for piglets born from SA sows compared with the control group (5.62 kg vs. 5.53, P &amp;gt; 0.05), respectively. Results suggest that the dietary inclusion of the sensory additive Luctamax Sows at 0.075% in the lactation diet from entry to the farrowing unit until weaning increased sows FI and prevented body reserves mobilization, having also benefits in the offspring, specially one week after farrowing. These results prove the potential of a sensory additive in helping the sows to cope with the lactation phase, especially under heat stress conditions.

PSXII-14 Effects of Feeding 10-G on Performance and Carcass Quality of Yearling Beef Steers

Abstract Life Products’ direct fed microbial, 10-G, is a lipid-coated and heat protected mixed culture containing Lactobacillus acidophilus, Enterococcus faecium, Pediococcus pentosaceus, Lactobacillus brevis, and Lactobacillus plantarum. Previous small-pen research has reported inconsistent benefits to performance and carcass characteristics from feeding 10-G. The objective of this trial was to evaluate the effects of feeding 10-G on growth performance and carcass quality in yearling steers. In this randomized complete block design, 6,400 yearling steers were allocated to treatment (10-G or control) within a block (n = 16), where pen served as experiment unit. Trial diets were composed of steam-flaked corn, wheat silage, corn silage, and Sweet Bran Plus. The addition of 10-G within the treatment diet was at an inclusion of 2 g·animal-1·day-1 to provide 1x109 cfu for approximately 170 days. Mean initial body weight was 358 kg and cattle were on feed for an average of 182 days. No differences (P &amp;gt; 0.10) were observed between treatments for dry matter intake (control: 9.75 vs 10-G: 9.80 kg), final body weight (control: 641vs 10-G: 641 kg), average daily gain (control: 1.55 vs 10-G: 1.55 kg/d), or feed efficiency (control: 2.85 vs 10-G: 2.87). When evaluating carcass characteristics, there were no differences (P &amp;gt; 0.10) for hot carcass weight (control: 415 vs 10-G: 413 kg) or liver abscess prevalence (control: 17.4 vs 10-G: 18.2%). However, dressed carcass yield was decreased (P = 0.05) by 0.17% for cattle fed 10-G (control: 64.51 vs 10-G: 64.34%). No differences (P &amp;gt; 0.10) were observed for marbling score (control: Small29 vs 10-G: Small27), ribeye area (control: 100.00 vs 10-G: 100.00 cm2), backfat thickness (control: 1.30 vs 10-G: 1.30 cm). USDA quality grade outcomes. In conclusion, the supplementation of 10-G direct fed microbial did not influence live or carcass performance within this trial.

PSXII-19 Effects of Feeding Hybrid Rye Grain as a Replacement for Barley Grain on Feed Intake, Growth Performance and Carcass Characteristics of Finishing Beef Cattle

Abstract The objective of this study was to evaluate effects of increasing hybrid rye as a replacement for barley grain on feed intake, growth performance, and carcass characteristics for growing and finishing cattle. Commercial steers (n = 360) with an initial body weight (BW) of 348 ± 6.6 kg were stratified by BW and randomly assigned to 1 of 24 pens (15 steers/pen) for growing (n = 8; 65 d) phase and re-randomized for the finishing (n = 6; 118 d) phase. The control diet (BCON) for the growing phase included 60.2% barley grain, 28.0% barley silage, 7.0% corn silage, 3.4% oat hulls, with the remainder as mineral, vitamins, and urea. Hybrid rye was then included by replacing 50 or 100% of the barley grain (DM basis). Treatments for the finishing phase included a control containing 10% hay, 85.2% barley grain, with the remainder coming from mineral and vitamins (FCON). Hybrid rye grain was included by replacing 33 (33R), 67 (67R), and 100% (100R) of the barley grain (DM basis). Data were analyzed using the MIXED procedure for each phase independently with carcass data analyzed using the GLIMMIX procedure of SAS (SAS version 9.4; SAS Institute, Inc. Cary, NC). There was no effect of hybrid rye inclusion on DMI or G:F during the growing phase, but ADG increased quadratically (P = 0.04) with 50% rye having the greatest value. During finishing, DMI decreased linearly as hybrid rye inclusion increased (P = 0.03). Average daily gain was quadratically affected (P = 0.03) with an initial increase from FCON to 33% rye followed by a decrease with increasing rye grain inclusion, but G:F was not affected (0.148 kg BW/kg DMI). There was no effect of hybrid rye inclusion on hot carcass weight, dressing percentage, back-fat thickness, ribeye area, marbling score, and yield score. Increasing the inclusion of hybrid rye quadratically (P &amp;lt; 0.01) increased the proportion of severe liver abscesses with an average of 34.6% severely abscessed livers when hybrid rye grain was included compared with 11.1% for FCON. Partial replacement of barley grain with hybrid rye may improve ADG without affecting DMI or G:F during the growing phase. However, replacing barley grain in finishing diets with hybrid rye decreases DMI, increases risk for severe liver abscesses, but does not affect feed conversion suggesting hybrid rye could replace up to 33% of the barley grain.