Understanding the effect of sex on energy requirements of hair sheep

Differences and/or similarities in the influence of sex class for hair sheep requirements remain inconclusive. Knowledge of energy requirements allows well-formulated diets to be provided which is crucial for improving animal production. We aimed to determine the effect of sex class on the net energy requirements of growing hair sheep in a multi-study approach. We used a data set composed of individual measurements of 382 hair sheep (299 non-castrated and 83 castrated males) from 11 studies that used the methodology of comparative slaughter. Net energy requirements for maintenance (NEm) were obtained by the regression between heat production and metabolizable energy intake. The metabolizable energy requirements for maintenance (MEm) were calculated by the iterative method, and the efficiency of use of metabolizable energy for maintenance (km) was obtained by NEm divided by MEm. The net energy requirements for gain (NEg) were estimated from retained energy (RE) against empty BW gain (EBWG). The efficiency of energy use for weight gain (kg) was obtained from the relationship between RE and the energy metabolizable intake for gain, removing the intercept. There was an effect of sex on NEg and two equations were generated: NEg (MJ/day) = 1.040 (±0.04055) × EBW0.75 × EBWG0.8767(±0.03293) and NEg (MJ/day) = 1.040 (±0.04055) × EBW0.75 × EBWG0.8300(±0.03468) (R2 = 0.86; MSE = 0.0037; AIC = -468.0) for non-castrated and castrated males, respectively. Sex class did not affect kg (P > 0.05) and one kg was generated (0.29). Sex did not affect kprotein (P = 0.14) and kfat (P = 0.32), assuming an average deposition efficiency of 0.27 for protein and 0.78 for fat. The NEm and MEm did not differ (P > 0.05) between sex classes, with a value of 0.272 and 0.427 MJ/kg0.75 EBW per day, respectively. The km observed was 0.64. In conclusion, non-castrated and castrated male hair sheep have similar maintenance energy requirements although energy requirements for gain differed among them. The Committees overestimate the gain and maintenance requirements for hair sheep. Therefore, the equations generated in this study are recommended.

Palm kernel cake in high-concentrate diets improves animal performance without affecting the meat quality of goat kids

Context Goat farming is an important socio-economic activity. The feedlot system allows the finishing of the animals in short periods through use of concentrated diets; however, these diets increase the system’s production costs. Palm kernel cake (PKC) has proved to be a good alternative feed source in diets for cattle and sheep because of its nutritional characteristics and potential to reduce production costs. Aim This experiment aimed to evaluate the effect of high-concentrate diets with the inclusion of PKC on carcass traits and meat quality of feedlot goat kids. Methods Thirty-two crossbred, castrated Boer goat kids, 4 months old and of average initial body weight 19.65±3.00kg, were used in the study. The animals were assigned to treatments in a completely randomised design, with four experimental diets containing PKC at 0%, 12%, 24%, and 36% on a dry matter basis. Measurements included total weight gain at slaughter, quantitative and sensory meat characteristics, and fatty acid profile. Key results A quadratic effect (P<0.05) on total weight gain, and on meat marbling, lightness, and yellowness, was observed. The highest total weight gain and marbling were recorded with the diet containing 12% PKC. Loin eye area was also highest at 12% PKC, then decreased, whereas protein content and shear force increased (P<0.05) at the higher PKC levels. Diet affected (P<0.05) saturated, monounsaturated, and polyunsaturated fatty acids. No effect was observed from the inclusion of PKC on sensory attributes or on nutritional quality of the lipid fraction of the meat. Conclusion It is recommended the use up to 12% of this alternative source of nutrients, owing to the higher total weight gain and improved quantitative aspects of the goat kids’ meat such as marbling and loin eye area. Implications High-concentrate diets and the use of by-products for animal nutrition have become common in animal production systems. The increasing use of PKC in animal nutrition leads us to determine the best dietary inclusion level, avoiding undesirable production or product quality characteristics.

Metabolizable amino acids and energy requirements of Nellore and crossbred Angus × Nellore bulls fed rations of different crude protein concentrations

Growth rate of cattle depends on their genetic makeup and nutrient intake. Moreover, increased growth rate may lead to increased amino acid (AA) requirements. Therefore, we evaluated the AA content of the empty body and estimated the net AA and energy requirements of purebred and crossbred beef bulls fed rations of different dietary CP concentrations. We performed a comparative slaughter experiment with 24 Nellore and 24 Angus × Nellore (A × N) bulls (8 months; initial shrunk BW: Nellore = 208.0 ± 12.78 kg; A × N = 221.9 ± 14.16 kg). Eight bulls (four Nellore and four A × N) were designated as the reference group, eight bulls (four Nellore and four A × N) were fed to maintenance level and 32 bulls (16 Nellore and 16 A × N) were fed ad libitum. The 32 bulls fed ad libitum were distributed using a completely randomized design in a 2 × 3 factorial scheme with two genetic groups (Nellore or A × N) and three dietary CP contents (100, 120 or 140 g CP/kg DM), being four groups with five bulls and two groups with six bulls. The experimental period lasted for 224 days. There were no interactions (P ≥ 0.056) between the dietary CP contents and genetic groups for any of the response variables. The dietary CP contents did not affect (P ≥ 0.062) the AA content in the empty body (g/kg empty BW [EBW]), with exception for Tryptophan (P = 0.027, linear effect). The dietary CP contents did not affect (P ≥ 0.051) AA content in the empty body (g/100 g of CP), with exception for Alanine (P = 0.013) that responded quadratically to dietary CP increase. The equations to estimate the net Lysine (Lys) and Methionine (Met) requirements (g/100 g of CP) were: Lys = 5.1 × EBW^0.0594 and Met = 1.7 × EBW^0.0255. Metabolizable Lys and Met to metabolizable energy (ME) ratios decreased as bulls EBW increased. Also, the metabolizable protein to ME ratio decreased as bulls EBW increased. In conclusion, the present study provides useful information regarding net and metabolizable requirements of AA of purebred and crossbred beef bulls. In the future, after the validation of the equations, these results can be used to calculate the AA requirements for growth of purebred and crossbred beef bulls. Nevertheless, it is important to highlight that the small sample size was one limitation of this present experiment.

Carbohydrate supplementation and psychophysiological responses during moderate exercise in hypoxia

Background

Rating of Perceived Exertion (RPE) is a subjective scale to monitor overload and fatigue during exercise. Hypoxia may worsen the perception of fatigue, compromising the self-reported perception of effort and increasing RPE. The objective was to evaluate the effects of carbohydrate (CHO) supplementation on RPE during exercise in hypoxia simulating 4200 m.

Methods

Eight male physically active volunteers performed two exercises at 50% VO_2peak and 1% slope: exercise in hypoxia + placebo or exercise in hypoxia + CHO (6% maltodextrin) with supplementation at 20, 40, and 60 min during exercise. Oxygen Saturation (SaO₂%) was assessed at baseline and after exercise, while RPE and HR were measured each 10 min during the trial.

Results

SaO₂% decreased after exercise in both conditions of hypoxia compared to rest. The RPE did not differ between groups. However, the RPE increased in hypoxia after 20 min of exercise in relation to 10 min. The Area Under the Curve (AUC) of RPE was lower in hypoxia + CHO compared to hypoxia. The AUC of the HR/RPE ratio in the hypoxia + CHO group was higher in relation to hypoxia.

Conclusions

Our results indicate that CHO supplementation does not change RPE induced by 60 min of exercise at 50% VO_2peak in hypoxia equivalent to 4200 m at the different times analyzed. However, in hypoxia + CHO the (AUC)-60 min of total RPE decreased during exercise, while the heart rate/RPE ratio improved, indicating lower RPE in the hypoxic environment.

A comparative study on the excretion of urinary metabolites in goats and sheep to evaluate spot sampling applied to protein nutrition trials

The main objective of this study was to establish a protocol to validate urine spot samples to estimate N excretion and microbial synthesis in goat and sheep; and to study factors that affect daily creatinine and purine derivatives (PD) urinary excretion. Also a performance trial was carried out to compare goat and sheep slaughtered after different feedlot periods. Twelve Boer goats (20.6 kg ± 3.4 initial BW) and 12 Dorper sheep (18.4 kg ± 2.3 initial BW), all 4-mo-old, males, were used. Eight animals (4 goats and 4 sheep) were randomly allocated to be slaughtered at 28, 56, and 84 d in feedlot. The experiment was conducted in a completely randomized design in a 2 × 3 factorial scheme, in which the factors were both species and the 3 feedlot periods. Diet consisted of 50% sorghum silage and 50% concentrate on a DM basis. Nutrient intake was higher (P < 0.01) for sheep than goats. Apparent digestibility of nutrients was similar (P > 0.05) in both species. Sheep had greater (P < 0.01) ADG and final BW than goats. Fat deposition and fat:muscle ratio was higher (P < 0.01) in sheep carcasses. Sheep had higher N urinary (P = 0.02) excretion and N retention (g/d; P < 0.01) than goats. Urinary N excretion increased linearly (P < 0.01) in response to feedlot period. However, feedlot did not affect (P = 0.20) N retention, but linearly reduced the relationship between N retained and ingested (P = 0.04) or apparently digested (P < 0.01). Microbial efficiency (P > 0.05) did not differ between species. Creatinine excretion (C mg/d; P < 0.01) was higher in sheep than goats. Purine derivatives (Ŷ) were related closely with OM intake (Ŷ = 0.013±0.0007X; r2 = 94). A difference (P < 0.01) was found between the allometric model for creatinine excretion (Ŷ) and muscle weight (X) for both species, and the following equations were obtained: Ŷ = 89.04(±31.44)X0.9797(±0.16) for goats and Ŷ = 109.8(±47.50)X0.8002(±0.20) for sheep. Creatinine concentration was greater during nocturnal than diurnal periods, with lower diurnal fluctuations. Sampling time did not affect (P = 0.27) the PD:C ratio. The urea (U):C ratio was higher (P < 0.01) in sheep than goats, and was also higher (P < 0.01) during diurnal than nocturnal sampling periods. Our results suggest that it is necessary to take 2 and 3 spot urine samples after feeding to estimate N compounds excretions in goats and sheep, respectively.

Nutritional evaluation and productivity of supplemented sheep grazing in semiarid rangeland of northeastern Brazil

Sheep production systems in Brazilian caatinga rangelands require supplementation adapted to changes in floristic and chemical composition as dry seasons progress. Meeting sheep nutritional needs in extensive semiarid systems is challenging because of sheep dietary preferences and habits. The objective of this trial was to evaluate the substitutive effect of concentrate supplementation on grazing sheep in the Brazilian caatinga rangeland and its consequences on performance in different seasons. The trial was conducted from March to August 2013 at Embrapa Goat and Sheep in Sobral, Ceará State, Brazil. Thirty-two Brazilian Somali multiparous ewes were submitted to estrus synchronization and controlled breeding. At the start of the trial, ewes averaged 30.45 + 2.60 kg body weight (BW). Ewes were divided into four groups and individually offered 0, 200, 350, or 500 g supplement head^-1 day^-1. Intake prediction and digestibility trials were evaluated at three periods: rainy season (April), transition rainy-dry (June), and dry season (August). Sheep weights were taken every 14 days to measure their performance from late gestation until weaning. Ewe BW and body condition score changes were determined too. Lamb BW changes were also measured every 14 days from birth through weaning. A completely randomized design with split plot arrangement using eight replications was used for intake and digestibility measurements. The differences between supplement offered (0, 200, 350, and 500 g sheep-1) and season (rainy, transition rainy-dry, and dry) were submitted to analyses of variance and multiple means were separated, where differences were detected, using the Tukey's test. During lactation up through weaning, ewes supplemented at 500 g day^-1 had greater BW than ewes without supplement. Ewes supplemented with 200 g concentrate head^-1 day^-1 had 9.1% greater (P ≤ 0.05) BW at weaning and their lambs had 19.7% greater birth and 16.6% heavier wean BW despite lower dry matter intake compared to unsupplemented animals. Supplementation with 200 g concentrate increased carrying capacity by 28.8% during the dry season and by 20.5% during the rainy season. This study confirmed that in the dry season, when quality of rangeland forages decreases, supplementation contributes to greater DMI, improves postpartum and lactation BW recovery of ewes, and contributes to greater lamb birth and wean weights. Moreover, supplementation leads to feed substitution effects that may increase rangeland resilience by mitigating overgrazing. Supplementation with 200 g concentrate can also prevent negative energy balance for grazing animals, improving longer postnatal recovery, longer intervals between parturitions, fewer double and is necessary to ensure a better BW at birth to lambs.

Dietary protein reduction on microbial protein, amino acid digestibility, and body retention in beef cattle: 2. Amino acid intestinal absorption and their efficiency for whole-body deposition

The objective of this study was to determine the apparent and true intestinal digestibility of total and individual AA, and to estimate the efficiency of whole-body AA retention from individual and total absorbed AA. Four Nellore animals (241.3 kg initial BW) and four crossbred Angus × Nellore (263.4 kg initial BW) cannulated in rumen and ileum were randomly allocated in two 4 × 4 Latin squares. The experiment lasted four 17 d periods, with 10 d for adaptation to diets and another 7 d for data collection. The diets consisted of increasing CP levels: 100, 120, or 140 g/kg of DM offered ad libitum, and restricted intake diet with 120 g CP/kg DM (experiment 1). In experiment 2, forty-four bulls (22 Nellore and 22 crossbred F1 Angus × Nellore) with 8 months and initial shrunk BW 215.0 ± 15.0 kg (Nellore = 208.0 ± 12.78 kg; Angus × Nellore = 221.9 ± 14.16 kg) were used. Eight of those animals were slaughtered at the beginning of the experiment. The remaining 36 bulls were allocated in a completely randomized design with six replicates, in a 2 (genetic groups) × 3 (CP contents) factorial scheme. The amount of essential AA (EAA) and nonessential AA (NEAA) reaching the small intestine increased linearly (P < 0.05) in response to CP content. The apparent digestibility of EAA was not affected (P > 0.05) by CP content, with exception for histidine (P = 0.07, linear effect), leucine (P = 0.01, linear effect), and methionine (P = 0.05, linear effect). Differences existed among AA when compared the apparent digestibility of NEAA. The apparent digestibility of alanine (P = 0.05), aspartic acid (P = 0.07), glutamic acid (P = 0.02), glycine (P = 0.05), proline (P = 0.02), and serine (P = 0.04) responded quadratically to CP content increase. However, the apparent digestibility of cystine and tyrosine was not affected (P > 0.05) by increasing dietary CP. The true intestinal digestibilities of total, essential, nonessential AA, lysine, and methionine were 75.0%, 77.0%, 74.0%, 77.0%, and 86%, respectively. The true intestinal digestibility of total microbial AA was 80%. The efficiency of utilization of total AA for whole-body protein deposition was 40%. The efficiency of utilization of lysine and methionine was 37% and 58%, respectively. It was concluded that the AA flow to the omasum increases in response to dietary CP content. In addition, there are differences among AA in the efficiency that they are used by beef cattle.

Does microbial nitrogen contamination affect the estimation of crude protein degradability of concentrate feeds?

The effects of microbial contamination (MC) on CP degradability of concentrate feeds are still controversial. Therefore, the aim of this study was to use N to estimate the impact of MC on estimations of CP fractions (the soluble fraction of CP [a], the insoluble but potentially degradable fraction of CP [b], and the rate of digestion of fraction b [kd]) of concentrate feeds. Twelve types of feed were evaluated: 6 energy concentrates-wheat bran ( L.), rice meal ( L.), ground corn ( L.), ground sorghum ( Pers.), ground corn cob ( L.), and soybean hulls [ (L.) Merr.]-and 6 protein concentrates-cottonseed meal ( L.), soybean meal [ (L.) Merr.], ground bean ( L.), peanut meal ( L.), sunflower meal ( L.), and corn gluten meal ( L.). The feeds were divided into 4 groups and were incubated in the rumen of 4 crossbred bulls. The samples were incubated for 0, 2, 4, 8, 16, 24, 48, and 72 h. To estimate the MC of the incubated residues, the ruminal bacteria were labeled with N via continuous intraruminal infusion of (NH)SO. There was no difference ( = 0.738) between corrected and uncorrected parameters a, b, and kd for all feeds that were evaluated. All of the feed tests followed an exponential model of degradation, and the model fitted well to the data, except for corn gluten meal, probably because the maximum incubation time that was used (72 h) was not long enough to allow for an accurate estimation of the degradation profile. Therefore, correction of ruminal protein degradation to MC is irrelevant with regards to the concentrates that were studied.

Reducing mineral usage in feedlot diets for Nellore cattle: II. Impacts of calcium, phosphorus, copper, manganese, and zinc contents on intake, performance, and liver and bone status

Weaned Nellore bulls ( = 36; 274 ± 34 kg) were used in a randomized block design with a 2 × 2 factorial arrangement of treatments to evaluate intake, fecal excretion, and performance with different concentrations of minerals. Experimental diets were formulated with 2 concentrations of Ca and P (macromineral factor; diet supplying 100% of Ca and P according to BR-CORTE () [CaP+] or diet without limestone and dicalcium phosphate [CaP-]) and 2 concentrations of microminerals (micromineral factor; diet with supplementation of microminerals [Zn, Mn, and Cu; CuMnZn+] or diet without supplementation of microminerals [Zn, Mn, and Cu; CuMnZn-]). The factor CaP- was formulated without the addition of limestone and dicalcium phosphate, and the factor CuMnZn- was formulated without inorganic supplementation of microminerals (premix). The diets were isonitrogenous (13.3% CP). Intake was individually monitored every day. Indigestible NDF was used as an internal marker for digestibility estimates. The bulls were slaughtered (84 or 147 d on feed), and then carcass characteristics were measured and liver and rib samples were collected. Feed, feces, rib bones, and liver samples were analyzed for DM, ash, CP, ether extract (EE), Ca, P, Zn, Mn, and Cu. There were no significant interactions ( ≥ 0.06) between macro- and micromineral supplementation for any variables in the study. Calcium, P, and micromineral concentrations did not affect ( ≥ 0.20) intake of DM, OM, NDF, EE, CP, TDN, and nonfiber carbohydrates (NFC). Calcium and P intake were affected ( < 0.01) by macromineral factor. Animals fed without Ca and P supplementation consumed less of these minerals. Dry matter and nutrient fecal excretion (OM, NDF, EE, CP, and NFC) were similar ( ≥ 0.23) among all factors. Performance and carcass characteristics were similar ( ≥ 0.09) among diets. The content of ash in rib bones was not affected by diets ( ≥ 0.06). Plasma P and phosphatase alkaline concentrations were similar ( ≥ 0.52) among diets. Supplementation of microminerals decreased ( < 0.01) plasma Ca concentration; nevertheless, all analyzed blood metabolites were within the reference values. Supplementation of Ca and P increased ( < 0.01) fecal excretion of these minerals. These results indicate that mineral supplementation (Ca, P, Zn, Mn, and Cu) of conventional feedlot diets for Nellore bulls may be not necessary. Dietary reductions in these minerals would represent a decrease in the cost of feedlot diets. Dietary reduction in Ca and P content cause a decrease in fecal excretion of these minerals, which, in turn, represents an opportunity to reduce the environmental impact of feedlot operations.

Effect of different forage types and concentrate levels on energy conversion, enteric methane production, and animal performance of Holstein × Zebu heifers

The aim of this study was to evaluate the effect of diets containing corn silage (CS) or sugarcane (SC) with 300 or 500 g/kg of concentrate (on a DM basis) on energy conversion, enteric methane (CH4) production, and the animal performance of Holstein × Zebu heifers. An experiment was conducted while using comparative slaughter. Twenty Holstein × Zebu heifers with an average age of 12 ± 1.0 months and an average bodyweight of 218 ± 36.5 kg were used. Four heifers were assigned to a baseline group, whereas the remaining 16 heifers were distributed in a completely randomised design using a 2 × 2 factorial scheme (n = 4), with two types of roughage (CS or SC) and two levels of concentrate (300 or 500 g/kg) on a DM basis of the diet over the course of 112 days. For the evaluation of the apparent total-tract digestibility of diets and energy losses, a digestibility assay was performed by using the total collection of faeces and urine over three consecutive days. The enteric CH4 production was quantified by continuous analysis of regular samples of air excreted by the animals throughout the day. The greatest (P < 0.05) average daily gain was observed for heifers that were fed CS-based diets or with 500 g/kg of concentrate. Greater (P < 0.05) daily CH4 emissions were observed for heifers that were fed 500 g/kg of concentrate; CH4 production as a function of DM intake was greater (P < 0.05) for heifers that were fed SC-based diets. The efficiency of the conversion from digestible energy (DE) to metabolisable energy (ME) was not influenced (P > 0.05) by variables that were analysed in this study. However, the mean value that was observed in the present study was above those values proposed by the main evaluation systems of feedstuffs and nutrient requirements of ruminants. Therefore, we concluded that CS-based diets allow for better animal performance of Holstein × Zebu heifers in relation to SC-based diets. Also, the increased concentrate improves the performance of growing heifers. A greater inclusion of concentrate in SC-based diets can allow for a reduction of CH4 emissions per consumed unit and per gain unit. The mean suggested value for the ME : DE ratio based on this study is 0.86. However, more studies are necessary to validate this result.

Influence of diets with silage from forage plants adapted to the semi-arid conditions on lamb quality and sensory attributes

Quality and sensory attributes of meat from 32 mixed-breed Santa Inês lambs fed diets composed of four silages with old man saltbush (Atriplex nummularia Lind), buffelgrass (Cenchrus ciliaris), Gliricidia (Gliricidia sepium), and Pornunça (Manihot sp.) were evaluated. Meat from lambs fed diet containing old man saltbush silage (P<0.05) showed greater values for cooking loss. Of the sensory attributes evaluated in the Longissimus lumborum muscle of the lambs, color and juiciness did not differ (P>0.05). However, the silages led to differences (P<0.05) in aroma, tenderness, and flavor values. The meat from animals fed the pornunça and Gliricidia silages was tenderer. Flavor scores were higher in meat from lambs that consumed old man saltbush silage and lower in the meat from those fed buffelgrass silage. Diets formulated with buffelgrass silage for sheep reduce meat production. Based on the results for carcass weight and meat quality, old man saltbush and pornunça are better silages for finishing sheep.

Effects of roughage sources produced in a tropical environment on forage intake, and ruminal and microbial parameters

Our objective was to study the effect of different roughage sources produced in a tropical environment on intake, digestibility, and ruminal parameters of crossbred bulls. Five rumen-fistulated 30-mo-old Holstein × Bos indicus bulls (average BW =459 ± 32.5 kg) were utilized in a 5 × 5 randomized Latin square design. The experiment consisted of five 19-d experimental periods (10 d for adaptation and 9 d for data collection) and 5 treatments. Experimental diets consisted of corn (Zea mays L.) silage (CS), Brachiaria grass (Brachiaria decumbens Stapf.) silage (BGS), elephant grass (Pennisetum purpureum Schumach.) silage(EGS), Tifton 85 (Cynodon spp.) hay (T85), and fresh sugarcane (Saccharum officinarum L.; SC). Diets were formulated to have approximately 11% CP (DM basis)using a mixture of urea and ammonium sulfate (9:1 ratio) that was diluted in water and then mixed with roughage. Intake, ruminal outflow, digestibility coefficients,ruminal pool, intake, passage (kp) and digestion rates, microbial parameters, and pH data were assessed.D ry matter intake was greater (P < 0.01) for CS compared with SC. Among treatments, lesser (P < 0.01)potentially digestible NDF, ash- and protein-free NDF(apNDF), and digestible ash- and protein-free NDF intake values were observed for SC. Ruminal outflows of DM and nonfibrous carbohydrates were lesser (P <0.01) for SC compared with other treatments. Dry matter apparent digestibility and ruminal digestibility did not differ (P > 0.27) among treatments. No differences (P = 0.11) were observed for ruminal apNDF pool and ruminal kp of apNDF (P = 0.06) among treatments. No treatment effect (P > 0.28) was observed for DM and nitrogen of rumen-isolated bacteria, and microbial efficiency was greater (P = 0.02) for BGS among treatments.A treatment × time interaction (P < 0.01) was found for ruminal pH, with a quadratic pattern in terms of time for CS, BGS, EGS, and T85, whereas pH values for CA linearly decreased as a function of time. In summary, these roughages, when supplemented with an additional nitrogen sources, show similar overall apparent digestibility and ruminal pool values, but conversely, bulls fed sugarcane had less overall nutrient intake and lower ruminal outflow and digestion rate values. We conclude that fresh-cut sugarcane, when provided with urea, can affect digestion rate and, consequently, impact nutrient intake.

Vitamin E supplementation inhibits muscle damage and inflammation after moderate exercise in hypoxia

BACKGROUND

Exercise under hypoxic conditions represents an additional stress in relation to exercise in normoxia. Hypoxia induces oxidative stress and inflammation as mediated through tumour necrosis factor (TNF)-α release that might be exacerbated through exercise. In addition, vitamin E supplementation might attenuate oxidative stress and inflammation resulting from hypoxia during exercise. The present study aimed to evaluate the effects of vitamin E supplementation (250 mg) on inflammatory parameters and cellular damage after exercise under hypoxia simulating an altitude of 4200 m.

METHODS

Nine volunteers performed three sessions of 60 min of exercise (70% maximal oxygen uptake) interspersed for 1 week under normoxia, hypoxia and hypoxia after vitamin E supplementation 1 h before exercise. Blood was collected before, immediately after and at 1 h after exercise to measure inflammatory parameters and cell damage.

RESULTS

Percentage oxygen saturation of haemoglobin decreased after exercise and recovered 1 h later in the hypoxia + vitamin condition (P < 0.05). Supplementation decreased creatine kinase (CK)-TOTAL, CK-MB and lactate dehydrogenase 1 h after exercise (P < 0.05). The exercise in hypoxia increased interleukin (IL)-6, TNF-α, IL-1ra and IL-10 immediately after exercise (P < 0.05). Supplementation reversed the changes observed after exercise in hypoxia without supplementation (P < 0.05).

CONCLUSIONS

We conclude that 250 mg of vitamin E supplementation at 1 h before exercise reduces cell damage markers after exercise in hypoxia and changes the concentration of cytokines, suggesting a possible protective effect against inflammation induced by hypoxia during exercise.

Reducing calcium and phosphorus in crossbred beef cattle diets: impacts on productive performance during the growing and finishing phase

Forty 3/4 Bos indicus × 1/4 Bos taurus bulls (initial bodyweight = 214 ± 4 kg; 11 ± 0.2 months) were used in the study. Four bulls were slaughtered as reference and the other 36 bulls were allowed ad libitum consumption of treatment diets following a completely randomised 3 × 3 factorial design. The design included three diet concentrations of calcium (Ca) and phosphorus (P): standard, 50% of standard, and 75% of standard and three periods of feedlot confinement: 8, 16, and 24 weeks with four bulls per treatment combination. The diets were isonitrogenous and consisted of 60 : 40 corn silage to concentrate. Dry matter intake, crude protein, ether extract, organic matter, non-fibrous carbohydrates, Ca, and P, expressed as kg/day, were greater (P < 0.05) for bulls confined for longer periods. Nutrient digestibility and average daily gain was not affected (P > 0.05) by Ca and P concentration of diet or by feedlot phase. Dressing were decreased (P < 0.05) for bulls that remained in confinement for a shorter period. The daily maintenance requirements of Ca and P were 13.66 and 21.51 mg/kg empty bodyweight, respectively, and the absorption coefficients of Ca and P were 0.70 and 0.67, respectively. We concluded that for crossbred cattle in the feedlot, dietary levels of Ca and P recommended by BR-CORTE (2010), NRC (2000), and AFRC (1991) could be reduced by 62%, 66%, and 57%, respectively, for Ca and by 14%, 15%, and 43%, respectively, for P with significant savings in costs. This study shows that Ca and P can be reduced to 1.8 and 2.2 g/kg DM respectively, in the diets for crossbred cattle in feedlot.

Matrilineage differentiation of the genus Tetragonisca using mitochondrial DNA markers and the polymerase chain reaction-restriction fragment length polymorphism technique

The Meliponinae are important pollinators of plant species, and one of the most managed species is Tetragonisca angustula. Initially, two subspecies were identified in T. angustula: T. angustula angustula and T. angustula fiebrigi. Subsequently, T. a. fiebrigi was considered a species, based on the coloration of its mesepisternum. The objective of the present study was to obtain genetic markers that could differentiate the two species by amplifying regions of mitochondrial DNA and conducting polymerase chain reaction-restriction fragment length polymorphism analysis. Worker bees were collected in three Brazilian states: Paraná (Maringá, Altônia, and Foz do Iguaçu), São Paulo (Dracena, São Carlos, and Santa Cruz do Rio Pardo), and Rondônia (Ariquemes). Ten pairs of insect heterologous primers were tested and four were used (primer pair 1, ND2 and COI; primer pair 2, COI; primer pair 8, 16S and 12S; and primer pair 9, COII). For the restriction analysis, 13 enzymes were tested: EcoRI, EcoRV, HindIII, HinfI, RsaI, PstI, XbaI, HaeIII, ClaI, XhoI, BglII, PvuII, and ScaI. Markers were obtained (primer pair 8 cleaved with EcoRV and XbaI and primer pair 9 cleaved with HaeIII, RsaI, and XbaI) that enabled matrilineage identification in the nests studied, which confirmed that hybridization could occur between both Tetragonisca species. The beginning of speciation was probably recent, and secondary contact has resulted in crosses between T. angustula females and T. fiebrigi males. Because of this hybridization, it would be appropriate to consider them as two subspecies of T. angustula.

Morfologia corporal de equinos quarto de milha puros e mestiços utilizados no laço comprido no Mato Grosso do Sul

Analisou-se pelagens, índices morfométricos (IM) e conformação (IC) de 125 equinos adultos da raça Quarto de Milha (QM), distribuídos em puros (67 fêmeas e 26 machos) e mestiços (24 fêmeas e 8 machos) utilizados em provas de Laço Comprido no Mato Grosso do Sul, Brasil. Estudou-se variação das pelagens a partir da simples contagem das ocorrências do fenômeno. Para análise dos IM, mensuram-se 28 medidas lineares e com base nessas, calculou-se 12 IC. Utilizou-se o método dos quadrados mínimos, com modelo contendo como fontes de variação os efeitos de sexo, grupo genético (equino puro ou mestiço) e interação grupo genético*sexo e estimaram-se correlação de Pearson entre os IM com os IC. As pelagens de maior predominância entre os equinos foram à alazã (42,40 %) e castanha (22,40 %). Observaram-se nos IM e IC (p

Energy and protein requirements of 3/4 Zebu × 1/4 Holstein crossbreds fed different calcium and phosphorus levels in the diet

The aim of this study was to determine the nutritional requirements of energy and protein for maintenance and weight gain of crossbred cattle, as well as their efficiencies. Fifty 3/4 Zebu × 1/4 Holstein crossbred bulls with initial weights of 214±4kg and aged 11±0.2 months on average were used in this experiment. Four animals were used in the reference group; ten bulls were fed at the maintenance level; and the remaining 36 bulls were fed ad libitum and distributed in a completely randomized design in a 3×3 factorial arrangement, which had three feedlot periods (56, 112 or 168 days) and three calcium and phosphorus levels (low, medium and normal) in the diet. Four of the maintenance animals had their heat production measured by respirometry at the Laboratory of Metabolism and Calorimetry of UFMG. After slaughter, composite samples, referred to as carcass and noncarcass samples were obtained from each animal. The net energy requirements for maintenance (NEm) and metabolizable energy for maintenance (MEm) were 68.9 and 90.1 kcal/EBW0.75/day, respectively. The efficiency (km) was 76.41%. The NEm requirement determined in the respirometry chamber was 85.5 kcal/kg0.75. The following equations were obtained for net energy for gain (NEg) and net protein for gain (NPg): NEg (Mcal/day) = 0.0505±0.000986 × EBW0.75× EBWG1.095 and NPg (g/day) = 162.79±18.2546 × EBWG - 1.30±5.3010 × RE. The efficiencies of fat and protein deposition were 70.04 and 15.12%, respectively. In conclusion, the requirements of NEm for growing and finishing non-castrated 3/4 Zebu × 1/4 Holstein crossbred cattle are 68.9 kcal/EBW0.75/day. Requirements of NEg and NPg can be obtained by the following equations: NEg(Mcal/day) = 0.05050.000986 × EBW0.75 × EBWG1.095and NPg (g/day) = 162.79±18.2546 × EBWG - 1.30±5.3010× RE.

Intake, digestibility, nitrogen efficiency, and animal performance of growing and finishing beef cattle fed warm-season legume (Stylosanthes capitata plus Stylosanthes macrocephala) silage replacing corn silage

It was hypothesized that Stylosanthes cv. Campo Grande (ES) silage could be used as the single source of dietary forage for beef cattle and that performance on ES would be similar to corn silage (CS) at a 50:50 forage:concentrate. The objectives of this study were to evaluate intake, total and partial digestibility of nutrients, ruminal pH, ruminal ammonia, and productive performance in growing beef cattle fed diets with varying proportions of ES silage replacing CS. Treatments consisted of diets with ratios of 0:100, 25:75, 50:50, 75:25, and 100:0% ES:CS. Two experiments were conducted simultaneously. In the first experiment, 10 crossbred Holstein-Zebu bulls with an average initial weight of 272 ± 86 kg were used. The bulls were rumen and abomasums fistulated. An experimental design of two 5 × 5 Latin squares (Exp. 1) was used. The second experiment used 40 Nellore bulls with an average BW of 386 ± 30 kg in a completely randomized design (Exp. 2). Results showed a linear increase in CP intake (P < 0.05) in response to increased dietary ES. An increase in the proportion of ES in the diet had a negative linear effect on TDN. Apparent ruminal digestibility of CP increased linearly, and apparent intestinal digestibility of nonfibrous carbohydrates increased with the addition of ES to the diet (P < 0.05). Intestinal digestibility of DM exhibited a quadratic response (P < 0.05). Nitrogen balance, excretion of urinary urea, and plasma urea nitrogen did not respond to the inclusion of ES in the diet (P > 0.05). There was also no effect (P > 0.05) of ES inclusion on animal performance. Ruminal pH was not affected by an increased proportion of ES in the diet (P > 0.05), but ruminal pH was affected (P < 0.05) by the time of collection, for which a cubic model fit the data. There was an interaction (P < 0.05) between treatment and collection time for ruminal ammonia nitrogen concentration. It can be concluded that ES silage can be used as a source of roughage in the diet of beef cattle during the growing and finishing phases at a proportion of 50% of DM in the total diet. Therefore, ES silage is a promising alternative dietary ingredient and the use of this alternative source of silage will depend on availability and economic factors.

Stigma receptivity, mode of reproduction, and mating system in Mesosetum chaseae Luces (Poaceae), a native grass of the Brazilian Pantanal

Mesosetum chaseae Luces, known regionally as "grama-do-cerrado", is abundant in the Pantanal region in Brazil and contributes significantly to livestock and environmental conservation. This species is under basic studies at Embrapa Pantanal (Nhecolândia subregion, Pantanal, Corumbá, MS, Brazil). In this study, we present data about stigma receptivity, mode of reproduction, and mating system for 10 accessions collected in Nhecolândia subregion (Pantanal). Stigma receptivity was optimal, producing innumerous oxygen bubbles upon testing with hydrogen peroxidase. Clarified ovaries analyzed under interference microscopy showed an embryo sac of the Polygonum type, typical of sexual species. The mating system, tested in protected flowers, indicated allogamy. These data are important for subsidizing future breeding programs for this species.

Chromosome number, microsporogenesis, microgametogenesis, and pollen viability in the Brazilian native grass Mesosetum chaseae (Poaceae)

The genus Mesosetum is a primarily South American genus with 42 species. Mesosetum chaseae, regionally known as 'grama-do-cerrado', is abundant in the Pantanal Matogrossense (Brazil); it is a valuable resource for livestock and for environmental conservation. We collected specimens from the Nhecolandia sub-region of the Brazilian Pantanal, located in Corumbá, Mato Grosso do Sul, Brazil. We examined chromosome number, ploidy level, meiotic behavior, microgametogenesis, and pollen viability of 10 accessions. All the accessions were diploid, derived from x = 8, presenting 2n = 2x = 16 chromosomes. Chromosomes paired as bivalents showing, predominantly, two terminal chiasmata. Interstitial chiasmata were rare. Meiosis was quite normal producing only a few abnormal tetrads in some accessions. Microgametogenesis, after two mitotic divisions, produced three-celled pollen grains. Pollen viability was variable among plant and accessions and was not correlated with meiotic abnormalities.

Genetic variability in local Brazilian horse lines using microsatellite markers

Genetic variability at 11 microsatellite markers was analyzed in five naturalized/local Brazilian horse breeds or genetic groups. Blood samples were collected from 328 animals of the breeds Campeira (Santa Catarina State), Lavradeira (Roraima State), Pantaneira (Pantanal Mato-Grossense), Mangalarga Marchador (Minas Gerais State), as well as the genetic group Baixadeiro (Maranhão State), and the exotic breeds English Thoroughbred and Arab. We found significant genetic variability within evaluated microsatellite loci, with observed heterozygosis varying between 0.426 and 0.768 and polymorphism information content values of 0.751 to 0.914. All breeds showed high inbreeding coefficients and were not in Hardy-Weinberg equilibrium. The smallest genetic distance was seen between the Pantaneira and Arab breeds. The principal component analyzes and Bayesian approach demonstrated that the exotic breeds have had a significant influence on the genetic formation of the local breeds, with introgression of English Throroughbred in Pantaneira and Lavradeira, as well as genetic proximity between the Arab, Pantaneira and Mangalarga Marchador populations. This study shows the need to conserve traits acquired by naturalized horse breeds over centuries of natural selection in Brazil due to the genetic uniqueness of each group, suggesting a reduced gene flow between them. These results reinforce the need to include these herds in animal genetic resource conservation programs to maximize the genetic variability and conserve useful allele combinations.

Immunotherapy with plasmid DNA encoding mycobacterial hsp65 in association with chemotherapy is a more rapid and efficient form of treatment for tuberculosis in mice

Tuberculosis (TB) remains a threat for public health, killing around 3 million people a year. Despite the fact that most cases can be cured with antibiotics, the treatment is long and patients relapse if chemotherapy is not continued for at least 6 months. Thus, a better characterization of the working principles of the immune system in TB and identification of new immunotherapeutic products for the development of shorter regimens of treatment are essential to achieve an effective management of this disease. In the present work, we demonstrate that immunotherapy with a plasmid DNA encoding the Mycobacterium leprae 65 kDa heat-shock protein (hsp65) in order to boost the efficiency of the immune system, is a valuable adjunct to antibacterial chemotherapy to shorten the duration of treatment, improve the treatment of latent TB infection and be effective against multidrug-resistant bacilli (MDR-TB). We also showed that the use of DNA-hsp65 alone or in combination with other drugs influence the pathway of the immune response or other types of inflammatory responses and should augment our ability to alter the course of immune response/inflammation as needed, evidencing an important target for immunization or drug intervention.

Effects of extracts from Brazilian sun-mushroom (Agaricus blazei) on the NK activity and lymphoproliferative responsiveness of Ehrlich tumor-bearing mice

Agaricus blazei Murrill, is an edible and medicinal mushroom which is popularly consumed due to its antitumoral properties. The immunomodulatory effects of methanol (METH), dichloromethane (DM) and n-hexane (HEX) extracts of this mushroom were evaluated in Ehrlich tumor-bearing mice. Subcutaneous inoculation of Ehrlich tumor cells inhibited the natural killer (NK) activity of spleen cells (specific lysis=6.18+/-2.56%) compared with normal mice (17.59+/-7.77%). Treatment of tumor-bearing mice with the extracts for 10 days restored the natural killer activity against Yac-1 target cells and the best results were observed by treatment with the HEX extract (21.48+/-5.26%). Treatment of the animals with the HEX extract for 10 days was also able to stimulate the mitogen-induced lymphoproliferative activity of spleen cells. Thirty days after the treatment, all groups presented low proliferative activity. Specific antibody production was observed to be higher in the groups treated with the DM or METH extract 30 days after the treatment. Analysis of the 3 extracts by gas chromatography mass spectrum (GCMS) and magnetic nuclear resonance (MNR) showed that the HEX extract contains mainly sugar and fatty acids and that the METH extract also contains sugar and possibly amino acids.

Single dose of a vaccine based on DNA encoding mycobacterial hsp65 protein plus TDM-loaded PLGA microspheres protects mice against a virulent strain of Mycobacterium tuberculosis

The high incidence of tuberculosis around the world and the inability of BCG to protect certain populations clearly indicate that an improved vaccine against tuberculosis is needed. A single antigen, the mycobacterial heat shock protein hsp65, is sufficient to protect BALB/c mice against challenge infection when administered as DNA vaccine in a three-dose-based schedule. In order to simplify the vaccination schedule, we coencapsulated hsp65-DNA and trehalose dimicolate (TDM) into biodegradable poly(DL-lactide-co-glycolide) (PLGA) microspheres. BALB/c mice immunized with a single dose of DNA-hsp65/TDM-loaded microspheres produced high levels of IgG2a subtype antibody and high amounts of IFN-gamma in the supernatant of spleen cell cultures. DNA-hsp65/TDM-loaded microspheres were also able to induce high IFN-gamma production in bulk lung cells from challenged mice and confer protection as effective as that attained after three doses of naked DNA administration. This new formulation also allowed a ten-fold reduction in the DNA dose when compared to naked DNA. Thus, this combination of DNA vaccine and adjuvants with immunomodulatory and carrier properties holds the potential for an improved vaccine against tuberculosis.

Observations on the thermal selection of the pantanal caiman (Caiman crocodilus yacare) hatchlings (Crocodylia: Alligatoridae)

Three options of water temperatures in a thermal gradient that changed from 22 to 35 degrees C were offered to Pantanal caiman (Caiman croocodilus yacare) hatchlings. Animals from two nests were submitted to temperatures during 19 days (Nest 1 -- 20 caimans caught in the nature hours after hatching), corresponding to 1 to 7 observations periods, and 13 days (Nest 2 -- 20 animals obtained by artificial incubation) relative to observation period 8. Caimans remain fasting during experimental period. Hatchlings were allocated in a enclosure containing three styrofoam boxes (120 L) disposed side by side enclosed by wire netting and filled with water to the top. Thus, the animals were free to access the boxes, which temperatures were changed at the end of each observation period to avoid position effects. Air temperature was keep close to 22 degrees C by air conditioning and water temperature was controlled by thermostats. The trial was divided in three phases determined by elimination of the less frequented temperature and its substitution by another temperature. In a first phase of the experiment that contained 1, 2 and 3 observation periods, the thermostats were regulated to 22 degrees C (BoxD), 26 degrees C (BxC) and 32 degrees C (BxA). In phase 2 to 26 degrees C, 29.5 degrees C (BxB) and 32 degrees C, including 4, 5 and 6 periods. In the third phase that included 7 and 8 periods, the thermostats were adjusted to 29.5 degrees C, 32 degrees C and 35 degrees C (BxE). The number of caimans in each box was recorded two to three times a day (8:00, 14:00 and 17:00h) before pointed water temperature. Mean water temperatures (+ standard deviation) and respective caiman frequency means by box/temperature were: Phase 1 (BxD/22.3 +/- 1.2 degrees C - 10.3%; BxC/27.0 +/- 2.4 degrees C - 32.0% and BxA/31.2 +/- 1.1 degrees C - 57.6%); Phase 2 (BxC/26.6 +/- 2.8 degrees C - 13.3%; BxB/29.3 +/- 2.2 degrees C - 27.7% and BxA/31.3 +/- 1.2 degrees C - 59.0%) and Phase 3 (BxB/29.5 +/- 3.6 degrees C - 23.7%; BxA/31.0 +/- 2.2 degrees C - 31.9 and BxE/34.0 +/- 2.2 degrees C - 44.4%). Observing that in the phases 1 and 2 the box with hottest water (CxA) was more frequented. In the phase 3, the difference between higher and smaller frequency straiten to 20.7%, in relation to almost 46.5% in phases 1 and 2, indicating that water temperatures between 29.5 and 35 degrees C resulted in body temperatures more next to the comfort zone, in the experimental conditions.