Residual feed intake (RFI) has been proposed as an index for determining beef cattle energetic efficiency. Although the relationship of RFI with feed conversion ratio (FCR) is well established, little is known about how RFI compares to other measures of efficiency. This study examined the phenotypic relationships among different measures of energetic efficiency with growth, feed intake, and ultrasound and carcass merit of hybrid cattle (n = 150). Dry matter intake, ME intake (MEI), ADG, metabolic weight (MWT), and FCR during the test averaged 10.29 kg/d (SD = 1.62), 1,185.45 kJ/(kg0.75 x d) (SD = 114.69), 1.42 kg/d (SD = 0.25), 86.67 kg0.75 (SD = 10.21), and 7.27 kg of DM/kg of gain (SD = 1.00), respectively. Residual feed intake averaged 0.00 kg/d and ranged from -2.25 kg/d (most efficient) to 2.61 kg/d (least efficient). Dry matter intake (r = 0.75), MEI (r = 0.83), and FCR (r = 0.62) were correlated with RFI (P < 0.001) and were higher for animals with high (>0.5 SD) RFI vs. those with medium (+/-0.5 SD) or low (<0.5 SD) RFI (P < 0.001). Partial efficiency of growth (PEG; energetic efficiency for ADG) was correlated with RFI (r = -0.89, P < 0.001) and was lower (P < 0.001) for high- vs. medium- or low-RFI animals. However, RFI was not related to ADG (r = -0.03), MWT (r = -0.02), relative growth rate (RGR; growth relative to instantaneous body size; r = -0.04), or Kleiber ratio (KR; ADG per unit of MWT; r = -0.004). Also, DMI was correlated (P < 0.01) with ADG (r = 0.66), MWT (r = 0.49), FCR (r = 0.49), PEG (r = -0.52), RGR (r = 0.18), and KR (r = 0.36). Additionally, FCR was correlated (P < 0.001) with ADG (r = -0.63), PEG (r = -0.83), RGR (r = -0.75), and KR (r = -0.73), but not with MWT (r = 0.07). Correlations of measures of efficiency with ultrasound or carcass traits generally were not different from zero except for correlations of RFI, FCR, and PEG, respectively, with backfat gain (r = 0.30, 0.20, and -0.30), ultrasound backfat (r = 0.19, 0.21, and -0.25), grade fat (r = 0.25, 0.19, and -0.27), lean meat yield (r = -0.22, -0.18, and 0.24), and yield grade (r = 0.28, 0.24, and -0.25). These phenotypic relationships indicate that, compared with other measures of energetic efficiency, RFI should have a greater potential to improve overall production efficiency and PEG above maintenance, and lead to minimal correlated changes in carcass merit without altering the growth and body size of different animals.

S. S. 2004. Association of a single nucleotide polymorphism in the bovine leptin gene with feed intake, feed efficiency, growth, feeding behaviour, carcass quality and body composition. Can. J. Anim. Sci. 84: 211-219. Leptin is a 16-kDa-hormone product of the obese gene synthesized and expressed predominantly by adipose tissues, which has been shown to play major roles in the regulation of body weight, feed intake, energy balance, fertility, and immune system functions. We report an investigation into the association of a previously identified cytosine to thymine missense mutation in exon 2 of the bovine leptin gene with feed intake, feed efficiency, growth, feeding behaviour, carcass quality and body composition in five genetic selection lines of a commercial population of beef cattle. Differences among genotypes in growth, feed intake and feed efficiency were not significant (P > 0.10) though steers homozygous for the thymine allele had positive residual feed intake (i.e., consumed more feed than expected) (+ 0.19 kg d -1 ) whilst steers homozygous for the cytosine allele had negative residual feed intake (-0.18 kg d -1 ). Steers carrying the thymine allele had a higher rate of gain in ultrasound backfat (P = 0.02), ultrasound backfat thickness (P = 0.06), higher carcass grade fat (backfat) (P = 0.005), lower yield grade (P = 0.01) and lower lean meat yield (P = 0.007). The thymine allele also tended to be associated with higher loin subcutaneous fat (P = 0.07) and was associated with higher brisket subcutaneous fat (P = 0.01), and brisket body cavity fat (P = 0.0001). No associations were found among the different genotypes and real-time ultrasound marbling, ultrasound longissimus thoracis area, carcass marbling and carcass longissimus thoracis area (P > 0.10). Our results show that animals carrying the thymine allele versus the cytosine allele may produce carcasses with poorer grades and lower lean meat yields but do not differ in carcass marbling or other fat depots.Key words: Beef cattle, leptin, feed intake, carcass merit Nkrumah, J. D., Li, C., Basarab, J. B., Guercio, S., Meng, Y., Murdoch, B., Hansen, C. et Moore, S. S. 2004. Association du polymorphisme d'un nucléotide du gène de la leptine bovine à la prise alimentaire, à la valorisation des aliments, à la croissance, aux habitudes alimentaires, à la qualité de la carcasse et à la composition corporelle. Can. J. Anim. Sci. 84: 211-219. La leptine est un dérivé hormonal 16-kDa du gène de l'obésité synthétisé et principalement exprimé par les tissus adipeux. On sait qu'elle joue un rôle important dans la régulation du poids, la prise d'aliments, le bilan énergétique, la fécondité et les fonctions du système immun. Les auteurs ont étudié l'association d'une mutation faux-sens entre la cytosine et la thymine rapportée antérieurement dans la partie exon 2 du gène de la leptine bovine avec la prise alimentaire, la valorisation des aliments, la croissance, les habitudes alimentaires, la qualité de la carcasse et la composition corporelle de cinq lignées d'...

OBJECTIVE To determine the number of lymph nodes that need to be examined to accurately stage the pN variable in patients undergoing radical nephrectomy (RN) for renal cell carcinoma (RCC). PATIENTS AND METHODS We reviewed the operative and pathology reports of 725 patients with RCC submitted for RN. All tumours were classified using the fifth edition of the Tumour‐Nodes‐Metastasis classification. For each patient the number of lymph nodes removed was recorded. The patients were divided into five different groups according to the number of nodes removed, i.e. group 1, 1–4; group 2, 5–8; group 3, 9–12; group 4, 13–16; and group 5, ≥ 17. We evaluated the factors that affected the number of lymph nodes removed with nodal dissection and the variables that influenced the incidence of nodal involvement. RESULTS Lymphadenectomy was performed in 608 patients (83.8%); in these patients the rate of lymph node metastases was 13.6%. The median (range) number of nodes removed was 9 (1–43); there was a statistically significant correlation between the number of nodes removed and the percentage of nodal involvement (r = 0.6; P < 0.01). The rate of pN+ was significantly higher in the patients with ≥ 13 than in those with < 13 nodes examined (20.8% vs 10.2%; P < 0.001). For organ‐confined and locally advanced tumours there was a statistically significant difference in the pN+ rate between patients with < 13 or ≥ 13 nodes examined (3.4% vs 10.5%, and 19.7% vs. 32.2%, respectively). CONCLUSIONS The proportion of tumours classified as pN+ increased with the number of lymph nodes examined. In RCC,> 12 lymph nodes need to be assessed for optimal staging.

This novel system of complete hepatic venous isolation and chemofiltration limits systemic chemotherapy toxicity and will allow use of higher doses of chemotherapeutic agents to treat HCC.

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