Brian Sullivan

Carnosine content in the porcine longissimus thoracis muscle and its association with meat quality attributes and carnosine-related gene expression

Muscle carnosine has pH-buffering, antioxidant and carbonyl scavenging properties, which may affect pork quality attributes. Study objectives were to: (1) compare muscle carnosine content and carnosine-related gene mRNA abundance in purebred pigs (n=282), (2) study the effect of muscle carnosine content on pork quality attributes and gene expression across breeds, and (3) study transcript abundance of carnosine-related genes in various tissues. Pigs were raised under similar conditions and slaughtered at 120±4.5kg. Longissimus thoracis muscles were sampled on the dressing line for gene expression and at 24h for meat quality measurements. Muscle carnosine content and carnosine-related gene mRNA abundance were modulated according to pig breeds. Greater pH24h, better water holding capacity and improved meat color values were found in pigs with high muscle carnosine content. Data suggest that high muscle carnosine is associated with improved pork meat quality attributes. The pig genetic background may be a key determinant for muscle carnosine content regulation.

Genomic data reveals large similarities among Canadian and French maternal pig lines

Abstract: Combining reference populations from different countries and breeds could be an affordable way to enlarge the size of the reference populations for genomic prediction of breeding values. Therefore, the main objectives of this study were to assess the genetic diversity within and between two Canadian and French pig breeds (Landrace and Yorkshire) and the genomic relatedness among populations to evaluate the feasibility of an across-country reference population for pig genomic selection. A total of 14 756 pigs were genotyped on two single nucleotide polymorphism (SNP) chip panels (∼65K SNPs). A principal component analysis clearly discriminated Landrace and Yorkshire breeds, and also, but to a lesser extent, the Canadian and French purebred pigs of each breed. Linkage disequilibrium (LD) between adjacent SNPs was similar within Yorkshire populations. However, levels of LD were slightly different for Landrace populations. The consistency of gametic phase was very high between Yorkshire populations (0.96 at 0.05 Mb) and high for Landrace (0.88 at 0.05 Mb). Based on consistency of gametic phase, Canadian and French pig maternal lines are genetically close to each other. These results are promising, as they indicate that the accuracy of estimated genomic breeding values may increase by combining reference populations from the two countries.

An efficient method for saliva collection from mature pigs to determine their enzymatic and electrolytic profiles

In this study, a novel ‘rope-assisted swab method’ for the collection of saliva samples from 45 adult pigs was established and validated. This method was efficient for harvesting 2 milliliters or more of saliva from each of the pigs for subsequent analyses within two min. The amount of α-amylase and lipase in the collected saliva samples was between 38−6,655 and 2−52 U/l, respectively. For HCO3− and electrolytes, the range was between 9−40, 15−76, 4.3−48.5 and 7−65 mM for HCO3−, Na+, K+ and Cl−, respectively. No significant differences in the enzymatic and electrolytic profiles were observed among sows with a high average litter size (SHA), sows with a low average litter size (SLA) and non-pregnant gilts (NPG) in this study. Our work reveals the efficiency of this collection method for mature pigs, and enzymatic and electrolytic profiling of saliva, which may be a useful reference for multiple diagnostic applications.

Impact of genetics and feeding on loin marbling levels of Canadian hogs

Intramuscular fat (IMF) is a highly heritable trait but is also strongly influenced by feeding strategies. Since 2009, loin IMF predicted on live pigs using ultrasonic scanning has been included in the Canadian swine technician accreditation program and in genetic evaluations for Duroc pigs. A research project involving 6,000 Duroc pigs scanned across Canada was designed to broaden the live IMF database and confirm genetic parameters estimated in a previous study. Data collected in the project were also used for genetic evaluation and selection of Duroc boars with extreme (high or low) breeding values for IMF to produce commercial pigs tested in two research trials (in Western and Eastern Canada) using two different feeding programs to study the impact of genetics and feeding on loin marbling levels.