Nucleotide sequence of myostatin gene and its developmental expression in skeletal muscles of Japanese Black cattle

Myostatin, a member of the transforming growth factor‐β superfamily, is a well known negative regulator of skeletal muscle growth. In the present study, the 6660 bp nucleotide sequence of the myostatin gene in Japanese Black cattle (JBC), including the entire coding region of 1128 bp, was determined. The amino acid sequence deduced from the nucleotide sequence of JBC was well conserved with its sequence of other cattle, although it was found that an Α→G transition at nucleotide position 641 results in the substitution of asparagine by serine at amino acid position 214. In order to examine the expression pattern of the myostatin gene in the skeletal muscles of JBC, its expression in three skeletal muscles, Semitendinosus (ST) muscle, Biceps femoris muscle and Longissimus lumborum muscle, of fetal and calf stages was analyzed by real time polymerase chain reaction. The highest level of the myostatin expression was observed in the fetal stage. In calf stages the highest expression was observed in ST muscle compared with the other two muscles. These results suggest that a higher expression of myostatin gene, especially in the fetal stage and in ST muscle during calf stages, is involved in the arrest in skeletal muscle growth and that its functional domains and genomic structure in JBC are well conserved with those in other mammals.     

Genetic parameter estimates of meat quality traits in Duroc pigs selected for average daily gain, longissimus muscle area, backfat thickness, and intramuscular fat content

Using a multitrait animal model BLUP, selection was conducted over seven generations for growth rate (ADG), real-time ultrasound LM area (LMA), backfat thickness (BF), and intramuscular fat content (IMF) to develop a new line of purebred Duroc pigs with enhanced meat production and meat quality. This selection experiment examined 543 slaughtered pigs (394 barrows and 153 gilts) from the first to the seventh generation for meat quality traits. Further, electric impedance and collagen content of loin meat were measured from the fourth to sixth generation. The present study was intended to estimate genetic parameters of the correlated traits of tenderness (TEND), meat color (pork color standard: PCS; lightness = L*), drip loss (DL), cooking loss (CL), pH (PH), electric impedance (IMP), and collagen (COL) of the LM, and the genetic trends of these traits. Respective heritability estimates for IMF, TEND, DL, CL, PCS, L*, PH, IMP, and COL were 0.39, 0.45, 0.14, 0.09, 0.18, 0.16, 0.07, 0.22, and 0.23. Genetic correlations of IMF with ADG and BF were low and positive, but low and negative with LMA. Tenderness was correlated negatively with ADG (-0.44) and BF (-0.59), but positively correlated with LMA (0.32). The genetic correlation between LMA and DL was positive and high (0.64). The genetic correlations of TEND with IMF and COL were low (-0.09 and 0.26, respectively), but a moderate genetic correlation (0.43) between COL and IMF was estimated, suggesting related increases of IMF and connective tissue. Genetic correlations among meat quality traits suggested that when IMF increases, the water holding capacity improves. Genetic trends of meat quality traits showed increased IMF and lighter meat color.     

Kinetics of Nitrogen Excretion by Cultured Flounder Paralichthys olivaceus

This study was undertaken to quantify the rate of nitrogen excretion by the cultured Japanese flounder as a function of body weight and water temperature. Measurements of the did rate of nitrogen excretion for the cultured flounder were made at mean water temperature of about 16, 19, and 23 C. The excretion rate of nilmgen was estimated by adding the nitrogen excreted in the forms of ammonia and urea nitrogens. The diurnal pattern in the excretion rate of nitrogen was governed mainly by the feeding time. The proportions of excreted ammonia to total nitrogen were 77.9% at 16 C, 84.5% at 19 C, and 83.2% at 23 C. The average was 81.9%. The relationship between the body weight and excretion rate of nitrogen ( E_N , mg N/fish per h) is expressed as E_N =α,.W', where α, = nitrogen excretion rate at temperature 0 . The parameter α, is dependent on water temperature, such that α, =α₂₀ Q₀₁^(0–200) where α₂₀= nitrogen excretion rate at 20 C, and Q₀₁, = temperature coefficient. The values of the kinetics parameters for the cultured flounder were found to be γ = 0.57, α₂₀= 0.060, and Q₀₁= 1.12.     

Genetic parameters for feed efficiency traits and their relationships with growth and carcass traits in Duroc pigs

Genetic parameters for feed efficiency traits of 380 boars and growth and carcass traits of 1642 pigs (380 boars, 868 gilts and 394 barrows) in seven generations of Duroc population were estimated. Feed efficiency traits included the feed conversion ratio (FCR), and nutritional (RFI(nut)), phenotypic (RFI(phe)) and genetic (RFI(gen)) residual feed intake. Growth and carcass traits were the age to reach 105-kg body weight (A105), loin eye muscle area (EMA), backfat (BF), intra-muscular fat (IMF) and meat tenderness. The mean values for RFI(phe) and RFI(gen) were close to zero and for RFI(nut) was negative. All the measures of feed efficiency were moderately heritable (h(2) = 0.31, 0.38, 0.40 and 0.27 for RFI(nut), RFI(phe), RFI(gen) and FCR respectively). The heritabilities for all growth and carcass traits were moderate (ranged from 0.37 to 0.45), except for BF, which was high (0.72). The genetic correlations of RFI(phe) and RFI(gen) with A105 were positive and high. Measures of RFI were correlated negatively with EMA. BF was more strongly correlated with measures of RFI (r(g) > or = 0.73) than with FCR (r(g) = 0.52). Selection for daily gain, EMA, BF and IMF caused favourable genetic changes in feed efficiency traits. Results of this study indicate that selection against either RFI(phe) or RFI(gen) would give a similar correlated response in carcass traits.