BackgroundFat deposits in chickens contribute significantly to meat quality attributes such as juiciness, flavor, taste and other organoleptic properties. The quantity of fat deposited increases faster and earlier in the fast-growing chickens than in slow-growing chickens. In this study, Affymetrix Genechip® Chicken Genome Arrays 32773 transcripts were used to compare gene expression profiles in liver and hypothalamus tissues of fast-growing and slow-growing chicken at 8 wk of age. Real-time RT-PCR was used to validate the differential expression of genes selected from the microarray analysis. The mRNA expression of the genes was further examined in fat tissues. The association of single nucleotide polymorphisms of four lipid-related genes with fat traits was examined in a F2 resource population.ResultsFour hundred genes in the liver tissues and 220 genes hypothalamus tissues, respectively, were identified to be differentially expressed in fast-growing chickens and slow-growing chickens. Expression levels of genes for lipid metabolism (SULT1B1, ACSBG2, PNPLA3, LPL, AOAH) carbohydrate metabolism (MGAT4B, XYLB, GBE1, PGM1, HKDC1)cholesttrol biosynthesis (FDPS, LSS, HMGCR, NSDHL, DHCR24, IDI1, ME1) HSD17B7 and other reaction or processes (CYP1A4, CYP1A1, AKR1B1, CYP4V2, DDO) were higher in the fast-growing White Recessive Rock chickens than in the slow-growing Xinghua chickens. On the other hand, expression levels of genes associated with multicellular organism development, immune response, DNA integration, melanin biosynthetic process, muscle organ development and oxidation-reduction (FRZB, DMD, FUT8, CYP2C45, DHRSX, and CYP2C18) and with glycol-metabolism (GCNT2, ELOVL 6, and FASN), were higher in the XH chickens than in the fast-growing chickens. RT-PCR validated high expression levels of nine out of 12 genes in fat tissues. The G1257069A and T1247123C of the ACSBG2 gene were significantly associated with abdominal fat weight. The G4928024A of the FASN gene were significantly associated with fat bandwidth, and abdominal fat percentage. The C4930169T of the FASN gene was associated with abdominal fat weight while the A59539099G of the ELOVL 6 was significantly associated with subcutaneous fat. The A8378815G of the DDT was associated with fat band width.ConclusionThe differences in fat deposition were reflected with differential gene expressions in fast and slow growing chickens.

The thyroid hormone responsive spot 14alpha (THRSPalpha) gene plays important roles in chicken growth and fat deposition. The aim of this study was to identify new variations in the gene to determine their effects on growth and fat traits in chicken and to observe the effects of the THRSPalpha gene on chicken lipid profile and lipoprotein and glucose and triiodothyronine effects on the THRSPalpha expression in liver and fat cells. Two new variations, namely A197835978G and G197836086A, and a reported 9-bp insertion-deletion (indel) of the THRSPalpha gene were genotyped by single-stranded conformational polymorphism in a Xinghua x White Recessive Rock F(2) full-sib resource population. The results showed that the A197835978G was significantly associated with hatch weight and BW at 28 d of age and breast muscle weight at 90 d of age in chickens (P < 0.05). The G197836086A was significantly associated with cingular fat width (P = 0.0349) and breast muscle crude fat content (P = 0.0349). The indel was significantly associated with abdominal fat weight (P = 0.0445). The above new THRSPalpha polymorphisms were also significantly associated with the total cholesterol and low-density lipoprotein, in which the THRSPalpha GA/AG genotype was associated with lipid and lipoprotein and the THRSPalpha BB indel genotype was significantly associated with liver weight in chicken breeds. The mRNA expression analysis in vivo and in vitro culture studies suggested that the THRSPalpha gene is more responsive to glucose than triiodothyronine. In conclusion, the 3 variations of the chicken THRSPalpha gene were associated with both growth and fat traits in this study. Such effects of the THRSPalpha gene were further supported from the data of observations in association analysis of the gene with phenotypic records and plasma lipid profiles, in the THRSPalpha gene expression in chicken development, and in vivo and in vitro cell culture observation of liver and abdominal fat tissues.

Breed improvement and conservation are optimally achieved when the available genetic resources are characterised and strategies developed to achieve the goals. This study aimed at investigating the management practices, performance and morphological features of the indigenous cattle ecotypes in Rwanda on 250 cattle farming households. A total of 20 measurements taken on 305 female and 45 male cattle were: body length (BL), height at withers (HW), leg height (LH), heart girth (HG), body weight (BW), tail length (TL), dewlap length (DL), dewlap width (DW), rump width (RW), ear length (EL), muzzle circumference (MC), horn length (HL), distance between horns (HS), hump length (HuL), hump width (HuW), navel depth (ND), udder length (UL), udder depth (UD), teat length (TL), and body condition score (BCS). Morphometric data was analysed by ecotype for each sex and age category since there were non-significant differences in geographical location. Results show that Rwanda has five types of indigenous cattle namely: Inyambo, Inkuku, Inkoromaijo, Inkungu and Bashi. The livestock system mostly used was extensive and household income was mainly from livestock. For Inyambo cattle, the popular ecotype, age at sexual maturity was 27.44±1.04 months for males and 28.76±1.02 months for female cows. Age at first calving was 33.8±0.83 months whereas calving interval was 13.60±0.45 months. Lactation length was found to be 6.84±0.29 months. The mean daily milk was 3.58±0.19 litres and the pre weaning calf survivability was 90±6.5%. Positive and high correlations were observed between BW, HG, HW, HuL, BL and HL. Indigenous cattle population of Rwanda are not homogenous by their morphological features and other productive traits, and therefore conservation will have to target the different ecotypes and this should be done with direct engagement of their keepers.

The success or failure of artificial insemination starts with the quality status of semen used, hence, this study aimed to investigate the effects of breed, season and year on bovine semen quality of the National Bull Stud of Rwanda kept at Masaka bull station, Rwanda. A total of 1475 semen samples were collected bi-weekly from nine bulls of Holstein Friesian (n = 3), Inyambo (n = 3) and Jersey (n = 3) breed using an artificial vagina. Semen volume, colour, concentration, mass motility, live sperm percentage and post-freeze motility were evaluated. Libido of the bulls at the time of semen collection was scored. Ejaculate volume, mass motility, individual motility, density and post freeze motility significantly differed (p < 0.05) among seasons of the year, bull breeds and age/year of collection. Friesian bulls had superior (p < 0.05) semen volume (5.76±0.08 ml) to that of Jersey (4.29±0.09 ml) and Inyambo (3.37±0.1 ml). However, Friesians had an inferior (p < 0.05) lighter coloured semen, with only 52.7% of Friesian samples having the preferred cream colour, as compared to 65.2% of Jersey and 64.9% of the Inyambo semen samples. Year of collection (2011 or 2012) and in essence age of the bull negatively affected (p < 0.05) all the parameters studied, with semen volume dropping from 5.16 to 5.10 ml, colour lightened from 62.8 to 54% of the samples being cream; mass motility fell from 2.98 to 2.65, while live sperm percentage in ejaculates dropped from 65 to 63%. Of the eight parameters studied, only post-freeze motility was not affected by passage of time. Semen collected during the October to December period had the best quality characteristics, though collections in the long rains (March to May) had comparable mass motility and post-freeze motility. Semen volume (4.61 ml per bull ejaculate) and post-freeze motility (39%) were poorest in the long dry season (January to February). In conclusion, the Friesian breed should be promoted at the bull station. Most semen should be collected during the rain season, particularly the short rains (October to November). Bulls below three years of age should be of focus.