Ractopamine does not rescue Halothane and Rendement Napole metabolism postmortem

The objective of this study was to determine if ractopamine (RAC) impacts postmortem muscle metabolism and subsequent pork quality in Halothane (HAL) and Rendement Napole (RN) mutant pigs. All RAC fed pigs had increased (P < 0.04) L* values. HAL and RN mutants muscle had lower (P < 0.01) pH values but RAC feeding had no effect. RN mutants had higher and lower (P < 0.05) muscle pH and temperatures, respectfully at 15 min and RN mutant pigs had greater (P < 0.0001) glycogen initially but lactate levels similar to wild type (WT) pigs at 24 h. RAC lowered (P < 0.05) glycogen in RN mutants but not in HAL mutated or WT pig muscle. These data show RAC feeding changes postmortem energy metabolism but does not change pH and pork quality hallmark of two major pig gene mutations and supports our contention that ultimate meat quality traits and their biochemical drivers may be more complex than originally reasoned.

Definition of Environmental Variables and Critical Periods to Evaluate Heat Tolerance in Large White Pigs Based on Single-Step Genomic Reaction Norms

Properly quantifying environmental heat stress (HS) is still a major challenge in livestock breeding programs, especially as adverse climatic events become more common. The definition of critical periods and climatic variables to be used as the environmental gradient is a key step for genetically evaluating heat tolerance (HTol). Therefore, the main objectives of this study were to define the best critical periods and environmental variables (ENV) to evaluate HT and estimate variance components for HT in Large White pigs. The traits included in this study were 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). Seven climatic variables based on public weather station data were compared based on three criteria, including the following: (1) strongest G×E estimate as measured by the slope term, (2) ENV yielding the highest theoretical accuracy of the genomic estimated breeding values (GEBV), and (3) variable yielding the highest distribution of GEBV per ENV. Relative humidity (for BFT, MDP, NBD, WN, and WW) and maximum temperature (for OTW, TNB, NBA, IBF, and IWE) are the recommended ENV based on the analyzed criteria. The acute HS (average of 30 days before the measurement date) is the critical period recommended for OTW, BFT, and MDP in the studied population. For WN, WW, IBF, and IWE, a period ranging from 34 days prior to farrowing up to weaning is recommended. For TNB, NBA, and NBD, the critical period from 20 days prior to breeding up to 30 days into gestation is recommended. The genetic correlation values indicate that the traits were largely (WN, WW, IBF, and IWE), moderately (OTW, TNB, and NBA), or weakly (MDP, BFT, and NBD) affected by G×E interactions. This study provides relevant recommendations of critical periods and climatic gradients for several traits in order to evaluate HS in Large White pigs. These observations demonstrate that HT in Large White pigs is heritable, and genetic progress can be achieved through genetic and genomic selection.

Review: Genetic selection of high-yielding dairy cattle toward sustainable farming systems in a rapidly changing world

The massive improvement in food production, as a result of effective genetic selection combined with advancements in farming practices, has been one of the greatest achievements of modern agriculture. For instance, the dairy cattle industry has more than doubled milk production over the past five decades, while the total number of cows has been reduced dramatically. This was achieved mainly through the intensification of production systems, direct genetic selection for milk yield and a limited number of related traits, and the use of modern technologies (e.g., artificial insemination and genomic selection). Despite the great betterment in production efficiency, strong drawbacks have occurred along the way. First, across-breed genetic diversity reduced dramatically, with the worldwide use of few common dairy breeds, as well as a substantial reduction in within-breed genetic diversity. Intensive selection for milk yield has also resulted in unfavorable genetic responses for traits related to fertility, health, longevity, and environmental sensitivity. Moving forward, the dairy industry needs to continue refining the current selection indexes and breeding goals to put greater emphasis on traits related to animal welfare, health, longevity, environmental efficiency (e.g., methane emission and feed efficiency), and overall resilience. This needs to be done through the definition of criteria (traits) that (a) represent well the biological mechanisms underlying the respective phenotypes, (b) are heritable, and (c) can be cost-effectively measured in a large number of animals and as early in life as possible. The long-term sustainability of the dairy cattle industry will also require diversification of production systems, with greater investments in the development of genetic resources that are resilient to perturbations occurring in specific farming systems with lesser control over the environment (e.g., organic, agroecological, and pasture-based, mountain-grazing farming systems). The conservation, genetic improvement, and use of local breeds should be integrated into the modern dairy cattle industry and greater care should be taken to avoid further genetic diversity losses in dairy cattle populations. In this review, we acknowledge the genetic progress achieved in high-yielding dairy cattle, closely related to dairy farm intensification, that reaches its limits. We discuss key points that need to be addressed toward the development of a robust and long-term sustainable dairy industry that maximize animal welfare (fundamental needs of individual animals and positive welfare) and productive efficiency, while also minimizing the environmental footprint, inputs required, and sensitivity to external factors.

Ractopamine changes in pork quality are not mediated by changes in muscle glycogen or lactate accumulation postmortem

Pork quality is a product of the rate and extent of muscle pH decline paced by carbohydrate metabolism postmortem. The beta-adrenergic agonist ractopamine (RAC) alters muscle metabolism but has little impact on pork quality. The objective of this study was to determine how feeding RAC alters postmortem carbohydrate metabolism in muscle. Muscle pH was higher early postmortem in pigs fed RAC for 2 wks compared to control, while other time points and temperatures were largely unaffected. Early postmortem, muscle lactate levels were reduced (P < 0.05) after feeding RAC for 1 and 2 wks. Similarly, pigs fed RAC for 4 wks had reduced (P < 0.05) glycogen levels early postmortem compared to control pigs, but unexpectedly, L* values (lightness) increased (P < 0.05) after inclusion of RAC in the diet for 4 wk. These data show RAC feeding reduces glycogen content and changes lactate accumulation postmortem, but raise questions about the role glycolytic flux has in driving pork quality development.

Utilisation of a mix of powdered oils as fat supplement in nursery- and growing-pig diets

Two experiments were conducted to challenge nursery and growing pigs to increased levels of dietary fat (5–10% as fed), using a crystallised powdered oil mix (CPOM), produced by a modified freeze-drying process. Growth performance of nursery pigs was determined and a digestibility trial was also conducted with growing pigs (Experiment 2). The CPOM was compared, at similar levels of lipid inclusion (10% total lipids), with other fat sources commonly used in swine diet, namely soybean oil (SBO) and hydrogenated palm oil. For the growth assay (Experiment 1), the CPOM was prepared and added at different levels (0%, 2.6% and 3.8%) commonly used in commercial diets (Phase 1–4 diets). Seventy-five weaning pigs (28 days of age) were housed in 15 pens (5 pigs per pen) and randomly assigned into the three dietary treatments until 70 days of age. Growth performance and feed utilisation were compared weekly among experimental groups. The use of CPOM improved average daily gain (~60%), and increased average daily feed intake by 40% and 50% at the 2.6% and 3.8% CPOM levels respectively. In the digestibility trial (Experiment 2), pigs fed with 5% incorporation of CPOM (10% of total lipid content) had digestibility of energy and ether extract similar to those fed the SBO-supplemented diet, although the SBO diet had a significantly greater polyunsaturated fatty acid concentration. The powdered crystallisation process of the CPOM fat allowed an equivalent digestibility of this fat source with more saturated fatty acids, and the physical-property effect of this processed oil source on apparent total-tract digestibility should be further studied.

Interactive effect of dietary protein and dried citrus pulp levels on growth performance, small intestinal morphology, and hindgut fermentation of weanling pigs

Weanling pigs ( = 108, 21 d of age, 5.82 ± 0.16 kg initial BW) were assigned to a 2 × 2 factorial arrangement of treatments to evaluate the effects of dietary levels of CP (high- and low-CP diets) and dried citrus pulp (DCP; 0% and 7.5%) on growth performance, small intestinal morphology, and hindgut fermentation. Pigs were blocked by initial BW and allotted to 1 of 9 pens, each containing 3 pigs. The high-CP diets consisted of feeding 20% and 21% CP levels throughout phase 1 (0 to 14 d) and phase 2 (14 to 28 d), respectively. For the low-CP diets, CP levels were reduced by 4% units as compared with the high-CP diets in both phases. Crystalline AA were supplied to maintain an ideal AA pattern. Pig BW and pen feed disappearance were recorded weekly. On d 7 and 28 postweaning, 1 pig from each pen was euthanized for collection of small intestinal tissues and digesta from cecum and colon. There were no CP × DCP interactions for growth performance and gut morphology. Although the low-CP diet decreased ADG ( = 0.03) and G:F ( = 0.02) from d 21 to 28 postweaning, overall performance was unaffected by the treatments. On d 7 postweaning, pigs fed the low-CP diet tended to have increased ( = 0.09) crypt depth in the duodenum. Low-CP diets tended to increase ( = 0.06) crypt depth and reduce ( = 0.08) villus:crypt ratio in the jejunum on d 7. Dietary treatments did not affect ileal morphology. On d 7 postweaning, low-CP diets tended to reduce ( = 0.09) cecal total VFA, whereas dietary DCP inclusion tended to decrease ( = 0.07) colonic propionate. Including 7.5% DCP to the diet decreased ( < 0.05) colonic isovalerate and ammonia N concentrations on d 7 only for pigs fed the low-CP diet. On d 28 postweaning, DCP inclusion in low-CP diets decreased ( < 0.05) butyrate, isovalerate, and valerate concentrations in the cecum, as well as isovalerate, valerate, and ammonia N concentrations in the colon. Including 7.5% DCP to the diet increased ( < 0.05) acetate:propionate ratio in the hindgut on both d 7 and 28 postweaning only for pigs fed the high-CP diet. Lactate concentration was unaffected by the treatments. These results indicate that feeding low-CP AA-supplemented diets did not compromise overall growth performance, but slightly increased damage in the gut morphology of weanling pigs. Moreover, adding 7.5% DCP to low-CP AA-supplemented diets shifted the fermentation pattern in the hindgut of weanling pigs by decreasing protein fermentation metabolites.

Analysis of lactation feed intakes for sows with extended lactation lengths

The objectives of this research were to quantify and model daily feed intakes to 28 d of lactation in modern sows. A total of 4,512 daily feed intake (DFI) records were collected for 156 Hypor sows from February 2015 to March 2016. The mean lactation length was 27.9 ± 2.0 d. The data included 9 parity 1, 33 parity 2 and 114 parity 3+ sows. Data were collected using a computerized feeding system (Gestal Solo, JYGA Technologies, Quebec, Canada). The feeding system was used to set an upper limit to DFI for the first 7 d of lactation. Overall, the least-squares means of a model including the random effect of sow indicated that DFI's continued to slowly increase to 28 d of lactation. The DFI data were fitted to Generalized Michaelis-Menten (GMM) and polynomial functions of day of lactation (t). The GMM function [DFI_i,t (kg/d) = DFI₀ + (DFI_A - DFI₀)(t/K)^C/[1 + (t/K)^C]] was fitted with 2 random effects for DFI (dfi_Ai) and intercept (dfi_0i) using the NLMIXED procedure in SAS®. The polynomial function DFI_i,t (kg/d) = [B₀ + B₁ t + B₂ t² + B₃ t³ + B₄ t⁴] was fitted with three random effects for B₀, B₁, and B₂ using the MIXED procedure in SAS®. Fixed effects models of the two functions had similar Akaike's Information Criteria (AIC) values and mean predicted DFI's. The polynomial function with 3 random effects provided a better fit to the data based on R² 30 (0.81 versus 0.79), AIC (14,709 versus 15,158) and RSD (1.204 versus 1.321) values than the GMM function with two random effects. The random effect for B₂ in the polynomial function allowed for the fitting of the function to lactation records that had decreased DFI after 15 d of lactation. The random effects for the polynomial function were used to sort the lactation records into three groups based on the derivative of the function at 21 d of lactation. Lactation records of the three groups had similar DFI the first two weeks of lactation (P > 0.40). The three groups of sows had substantially different DFI's after 18 d of lactation (P < 0.028). The differences in both actual and predicted DFI's between the three groups increased with each day of lactation to day 28 (P < 0.001). Mixed model polynomial functions can be used to identify sows with different patterns of DFI after 15 d of lactation.

Ractopamine with dietary lysine concentrations above basal requirements of finishing barrows improves growth performance, carcass traits and modifies the mTor signalling pathway

A 28-day study was conducted to evaluate the effects of three step-up levels of ractopamine hydrochloride (RAC) together with two additional levels of standardised ileal digestible lysine (Lys) above the basal requirements on growth performance, carcass characteristics and the mechanism of action on adipose and muscle tissue. In all, 108 finishing pigs (initial bodyweight 75.37 kg ± 2.88) were used for growth data and 54 pigs for carcass data. Samples from 18 pigs were used for the molecular study. Pigs were blocked by initial bodyweight and allotted to one of the following nine treatments: negative control (NC) without addition of RAC or Lys supplementation, constant 7.5 mg/kg RAC, 5 mg/kg RAC for 14 days, followed by 10 mg/kg for 14 days (Step-up 1), 5 mg/kg RAC for 21 days, followed by 10 mg/kg for 7 days (Step-up 2) and 5 mg/kg RAC for 7 days followed by 10 mg/kg for 21 days (Step up 3); on constant and step-up treatments were added 15% or 30% Lys above the basal level, giving a 4 × 2 + 1 factorial with six replicates. Loin muscle and fat tissue were collected for carcass-characteristic analysis and western blotting for p-AKT, p-P70S6K and carnitine palmitoyltransferase I. Feeding RAC increased gain to feed ratio and efficiency of energy utilisation (EF) from Day 0 to Day 13 (P &lt; 0.05) compared with NC. From Day 14 to Day 27, greater average daily gain (ADG) was observed in RAC-treated animals (P &lt; 0.05), except in the Step-up 2 with 30% additional Lys. During the second half of the trial, RAC positively affected ADG, gain to feed ratio and EF (P &lt; 0.01), while a Step-1 versus Step-2 effect was observed for ADG (P &lt; 0.03). For the overall period, RAC-treated pigs had greater ADG than did NC pigs (P &lt; 0.05). An average of 8.1% improvement on feed efficiency and 30% improvement on EF were observed for RAC-fed pigs in comparison to NC pigs (P &lt; 0.05). Chilled carcass weight and loin eye area were increased in pigs fed RAC (P &lt; 0.01). Western blotting showed greater p-P70S6K in muscle samples from pigs fed RAC with 15% additional Lys than in those from NC pigs (P &lt; 0.10). RAC was effective at improving efficiency of production. Lys supplementation of 15% was enough for optimal performance of the pigs in the present study; however, step-up programs did not outperform RAC-constant programs. Results of the present study suggest that RAC stimulates protein synthesis through the mTOR signalling pathway.