Even though the concept of residual feed intake (RFI) is well accepted, several questions remain regarding other traits that may be associated with selection for decreased RFI. These include DM digestibility, carcass composition, profitability, and performance. The objective of this study was to investigate the difference in those traits between low- and high-RFI cattle. Sixty Angus x Hereford crossbred steers (296 kg of initial BW) were fed a corn-based finishing ration (1.68 Mcal of NE(m)/kg, 13% CP on a DM basis) during 2 periods of 60 d each. For both phases, the regression equation fitted without the intercept (not statistically significant) was DMI (kg/d) = 0.0701 x BW(0.75) + 2.714 x ADG, r(2) = 0.42. The 15 greatest and least RFI steers were classed as high and low RFI groups. There were no differences between low and high RFI groups for days on feed (162 vs. 168 d), slaughter weight (503 vs. 511 kg), HCW (317 vs. 315 kg), LM area (76.5 vs. 77.1 cm(2)), backfat (1.23 vs. 1.27 cm), KPH (3.1 vs. 3.7%), quality grade (average Choice for both groups), or carcass fat (32.4 vs. 33.1%). Visceral organ masses and abdominal fat were similar for low and high RFI groups (32.25 vs. 31.24 kg and 37.48 vs. 36.95 kg, respectively). These results do not support the existence of major differences in composition and organ mass between low and high RFI steers at slaughter. The RFI grouping had a significant effect on DMI, G:F, and RFI values. Stepwise regression showed that G:F alone or DMI and ADG together explained 98.5% of the variance in cost of BW gain, whereas RFI alone explained only 18%. We conclude that RFI is less useful than G:F as an indicator of feedlot efficiency and profitability.

A total of 120 pigs [Duroc × (Landrace × Large White); initial average BW: 100.3 ± 2.5 kg] were used to investigate the effects of sex (barrows and gilts) and dietary total Lys restriction (7.0, 6.5, and 6.0 g·kg(-1)) on growth performance and carcass, meat, and fat characteristics. Pigs were intended for high-quality dry-cured ham from Spain (called Teruel ham), and a minimum fat thickness at the gluteus medius muscle (GM) is required (16 mm) for carcasses to be acceptable. Animals were slaughtered when they reached 129.0 ± 3.6 kg of BW. There were 6 treatments arranged factorially (2 sexes × 3 dietary Lys concentrations) and 4 replicates of 5 pigs per treatment. Barrows consumed more feed (P = 0.001) and tended to have less G:F (P = 0.06) than gilts. Carcasses from barrows were fatter (P = 0.001) and had heavier main trimmed lean cuts (P = 0.008) than gilts. A greater proportion of final acceptable carcasses for Teruel ham (P = 0.001) was observed in barrows than in gilts because of the greater percentage of carcasses that fulfill the minimum fat depth at GM required (P = 0.001). Meat from barrows had greater content of intramuscular fat (P = 0.02) than meat from gilts. Also, subcutaneous fat from barrows had less proportion of PUFA than fat from gilts (P = 0.02). A reduction in dietary Lys concentration decreased ADG (P = 0.004) and ADFI (P = 0.001) in pigs. In addition, backfat depth (P = 0.007) and fat at GM (P = 0.07) increased as dietary Lys decreased. The proportion of carcasses that fulfilled the minimum fat depth at GM required for Teruel ham increased as dietary Lys decreased in feed, but this effect was greater in gilts than in barrows (sex × Lys, P = 0.02). Meat and fat quality was not influenced by dietary treatment. We conclude that different feeding programs with different dietary Lys concentrations may be needed for barrows and gilts intended for production of dry-cured hams where a minimum carcass fat depth is required.

Brucellar spinal epidural abscesses (BSEA) are rare and very few series of them have been reported. In order to evaluate the clinical characteristics, management and outcome of this entity, the clinical records and current status of a series of 11 patients have been retrospectively reviewed. A series of 11 patients treated for BSEA in our Service during a period of 12 years (1989-2000) have been retrospectively studied. Spinal epidural abscesses (SEA) were diagnosed by MRI, CT or at surgery. Brucellar aetiology of SEA was considered when seroagglutination tests were positive at a titre of 1/160 or higher, and/or Brucella spp. were isolated in the blood or sample cultures. Ten of the 11 cases were treated with rifampicin plus doxycycline and in the remaining patient streptomycin was added because of a poor initial response. Six patients underwent surgical decompression and debridement of the SEA. Outcome was excellent in nine cases and good in two. There was no mortality and only one patient recovered incompletely from preadmission neurological deficits. Although BSEA is considered to be an unusual complication of spondylitis, our findings show that in some cases it can follow direct haematogenous spread to the extradural space. Surgical treatment must be undertaken when major neurological deficits are present. If antibiotic treatment is chosen as the initial therapy, the possibility of sudden neurological deterioration must be taken into account. Contrary to the high morbi-mortality rates reported in pyogenic or tuberculous SEA, BSEA has a good prognosis with early diagnosis and appropriate management.

The effects of different feeding strategies (0.7 kg/d target ADG [LO] and 1.0 kg/d target ADG [HI] during the lactation period (LACT; 0-6 mo) and the rearing period (REAR; 6-15 mo; HI-HI, HI-LO, LO-HI, and LO-LO treatments) on the growth and reproductive parameters of beef heifers bred by fixed-time AI at 15 mo were analyzed. Animal weights were recorded weekly (from birth to 18 mo), and size measures were recorded at 6 and 15 mo. Heifers were bled to determine the onset of puberty and the metabolic and endocrine (IGF-I and leptin) status. During lactation, calves in the high lactation treatment (LactHI) had greater weight ( < 0.001), weight gain ( < 0.001), and body size ( < 0.001) than calves in the low lactation treatment (LactLO). The greater energy balance of LactHI heifers at weaning was reflected in greater concentrations of plasma glucose (< 0.001), urea ( < 0.001), and IGF-I ( < 0.001); plasma levels of NEFA were lower ( < 0.001). During REAR, LactLO heifers had a greater growth rate than did LactHI heifers ( < 0.001), partially overcoming the lower gains during lactation. The differences in size measurements registered at weaning were also compensated, with the exception of LO-LO heifers. The IGF-I profile was highly correlated with animal performance traits and metabolic profiles, providing a useful indicator of growth, nutritional, and metabolic status at key points in development. By contrast, the function of leptin as an indicator of growth and reproductive development of heifers was less clear. All treatments had similar weights at puberty onset (55.9% mature BW), although LactLO ( < 0.01) and the low rearing treatment (RearLO; < 0.001) heifers were older than the others. The animals with greater glucose and IGF-I levels at weaning and greater cholesterol concentrations during REAR reached puberty earlier. The fertility rate (86%) was similar among treatments. The heifers in the high rearing treatment (RearHI) required more AI services to become pregnant and were older at conception ( < 0.05). The age of conception was positively correlated with glucose ( = 0.57, < 0.01) and cholesterol ( = 0.68, < 0.001) at 9 mo. Our results show that a 0.7 kg/d gain from birth allowed the first breeding at 15 mo, 6 mo earlier than usual for these conditions, without any negative effect on heifer reproductive performance.

The aim of this study was to examine the effects of 2 postweaning feeding management approaches (FEED: 0.8 [HIGH] vs 0.6 [MOD] kg/d target ADG) on the performance of heifers of 2 beef breeds (BREED: Parda de Montaña [PA] vs Pirenaica) calving at 2 yr. Twenty-five heifers previously creep fed before weaning (6 mo) were assigned to 2 planes of nutrition from 6 to 15 mo of age. At 15 mo, they were inseminated, and then received similar diets until weaning of their first calf (4 mo postcalving). Several parameters were measured to analyze growth and development (BW; ADG; size measures at 6 mo, 15 mo, calving, and weaning), performance at puberty and first breeding, and dam and calf performance in the first lactation (calving traits, ADG, milk yield). Metabolic (glucose, cholesterol, NEFA, β-hydroxybutyrate, and urea) and endocrine status (IGF-I and leptin) were assessed in plasma samples collected every 3 mo from 6 mo to calving and monthly during lactation. No interaction between BREED and FEED was observed. Heifers from the HIGH feeding treatment had higher postweaning ADG than those on the LOW diet. At 15 mo, they had greater BW, heart girth, and external pelvic area, but they did not differ thereafter. All heifers reached puberty at similar BW (55% mature BW) but different ages. Heifers from the HIGH treatment tended (P < 0.09) to be pubertal earlier, and PA heifers were 1.6 mo younger than Pirenaica heifers (P < 0.05) at puberty. At the time of conception (452 ± 59 kg) and calving (471 ± 51 kg), BW was above common recommendations in all groups. Calving traits and performance in lactation did not differ between feeding treatments. BREED only influenced birth weight; PA calves being heavier (P < 0.05), which resulted in a larger calf/cow BW ratio, but no effect on calving difficulty or subsequent performance. Metabolic substrates and hormones depended mostly on sampling date, which was related to current energy and protein intake. Glucose (P < 0.001), cholesterol (P < 0.001), and IGF-I (P < 0.05) were greater during the postweaning phase in heifers on the HIGH diet, and persistent physiological effects were observed during lactation. Age at puberty was negatively related with IGF-I (r = -0.43, P < 0.001), but not with leptin concentrations. In conclusion, regardless of breed, a moderate growth rate ensured adequate heifer development and performance until the first lactation, whereas no advantage was gained from enhanced postweaning gains.