Microbial biomass and activity are useful indices for assessing changes in soil ecosystems. The impact of different pastures on microbial biomass and activity was studied in a long-term experiment in Northeast Brazil. For our study the pastures were divided into plots: a) Brachiaria brizantha; b) Leucaena leucocephala; c) Cynodon dactilon; d) Panicum maximum. An adjacent area with native vegetation was used as reference. Soil samples were collected in 0-10 and 10-20 cm depths. No significant differences in soil organic C (Corg) was found among all plots at 0-10 and 10-20 cm depth. Soil microbial C (Cmic) values were higher in native forest and P. maximum when compared to the other plots. The soil basal respiration (CO2) values were similar among all plots evaluated. However, respiratory quotients (qCO2) were significantly lower in native forest and P. maximum when compared to other plots, at 0-10 cm depth. Values of fluorescein diacetate (FDA) hydrolysis were significantly higher in native forest and P. maximum, while values of dehydrogenase activity were found to be signif icantly higher in native forest, C. dactilon and P. maximum. Soil microbial biomass and activity changed when a native forest was converted to pastures. These changes were positive with the inclusion of P. maximum by the high input of C sources.

In Brazil, the majority of dairy cattle are Holstein × Gyr (H×G). It is unknown whether excessive energy intake negatively affects their mammary development to the same extent as in purebred Holsteins. We hypothesized that mammary development of H×G heifers can be affected by dietary energy supply. We evaluated the effect of different average daily gains (ADG) achieved by feeding different amounts of a standard diet during the growing period on biometric measurements, development of mammary parenchyma (PAR) and mammary fat pad (MFP), and blood hormones. At the outset of this 84-d experiment, H×G heifers (n = 18) weighed 102.2 ± 3.4 kg and were 3 to 4 mo of age. Heifers were randomly assigned to 1 of 3 ADG programs using a completely randomized design. Treatments were high gain (HG; n = 6), where heifers were fed to gain 1 kg/d; low gain (LG; n = 6), where heifers were fed to gain 0.5 kg/d; and maintenance (MA; n = 6), where heifers were fed to gain a minimal amount of weight per day. Heifers were fed varying amounts of a single TMR to support desired BW gains. Over the 84 d, periodic biometric and blood hormone measurements were obtained. On d 84, all heifers were slaughtered and carcass and mammary samples were collected. At the end, HG heifers weighed the most (181 ± 7.5 kg), followed by LG (146 ± 7.5 kg) and MA (107 ± 7.5 kg) heifers. The ADG were near expected values and averaged 0.907, 0.500, and 0.105 ± 0.03 kg/d for HG, LG, and MA, respectively. In addition, body lengths, heart girths, and withers heights were affected by dietary treatment, with MA heifers generally being the smallest and HG heifers generally being the largest. Body condition scores differed by treatment and were highest in HG and lowest in MA heifers; in vivo subcutaneous fat thickness measurement and direct analysis of carcass composition supported this. The HG heifers had the heaviest MFP, followed by LG and then MA heifers. Amount of PAR was highest in LG heifers and was the same for HG and MA heifers. The percentage of udder mass occupied by PAR was lowest in HG heifers, differing from LG and MA heifers. Composition of MFP was not evaluated. Regarding PAR composition, no differences in ash or DM were found. On the other hand, CP concentration of PAR for HG heifers was lower than that for LG heifers, which was lower than that for MA heifers. Regarding the fat content, HG treatment was higher than LG and MA treatment, which did not differ from each other. In PAR, differences in relative abundance of genes related to both stimulation and inhibition of mammary growth were observed to depend on dietary treatment, sampling day, or both. The same can be said for most of the blood hormones that were measured in this experiment. In this experiment, high ADG achieved by feeding different amounts of a standard diet during the growing period negatively affected mammary development.

Two experiments were carried out to evaluate the effects of corn and sorghum with different processing methods on the expression of genes involved in volatile fatty acids transport and pH regulation, and ruminal keratinization in rumen epithelium of finishing bulls. For Exp. 1, five rumen cannulated Nellore bulls were used in a 5x5 Latin square arrangement, with 14 d for adaptation and 9 d for sample collection. Treatments were: dry ground corn, dry ground sorghum, reconstituted corn, reconstituted sorghum, and control (forage-based diet). Samples of rumen epithelium from ventral sac were excised, rinsed, snap-frozen and stored at -80°C until total RNA isolation and quantitative real-time PCR analysis. In the Exp. 2, 24 Nellore bulls were assigned to a completely randomized design lasting 168 d. Experimental treatments were similar to those at Exp. 1, but without the control treatment. After the experimental period, bulls were slaughtered and rumen epithelium samples were rapidly excised for further histological analysis. Rumen epithelial tissue from animals fed reconstituted corn had lower expression of downregulated-in-adenoma (P = 0.03) and Na+/H+ exchanger 2 (trend; P = 0.09). The expression of Na+/ H+ exchanger 1 (P = 0.10) and putative anion transporter (P = 0.06) tended to be lower in rumen epithelium of bulls fed reconstituted grains. Ruminal concentration of valerate was greater for animals fed reconstituted grain (P = 0.01). Likewise, animals fed reconstituted corn tended to have greater butyrate ruminal concentration (P = 0.08). Keratinized layer thickness did not differ among treatments (P > 0.10). Therefore, reconstituted grains (especially corn) decrease the mRNA expression of genes involved in volatile fatty acids transport and pH control in the rumen epithelium.

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SummaryThe present study tested the hypothesis that insulin sensitivity would be lower in horses adapted to sugar and starch than those adapted to fat and fiber during an endurance race. Forty horses were divided into 3 dietary groups: one group of experimental feed (SS) was rich in starch (33%), low in fat (8%); another (FF) low in starch (6%) and rich in fat (15%); and a third group of commercial concentrates (CC) was intermediate in starch (16%) and fat (11%). Blood samples were taken the day before the race (PRE), within 3 minutes of arrival at each vet check (after 27, 48, 80 km), and three hours post completion or elimination. Plasma samples were analyzed for glucose, insulin, cortisol, glycerol, triglycerides, CK and AST. A proxy for insulin sensitivity as measured by the minimal model was calculated: RISQI = (1/sqrt [insulin]). Also, a proxy for pancreatic !-cell response to plasma glucose was calculated: MIRG =[ 800-0.30 ([insulin] -50) 2 ]/[glucose -30]. Higher insulin in FF and CC horses, and in eliminated horses, combined with a lower RISQI in eliminated horses indicated that insulin resistance (low RISQI) was attenuated by fat and fiber feeding and decreased the likelihood of elimination. Higher insulin sensitivity in finishers and fat and fiber fed horses may have allowed a more efficient glucose uptake by muscles, allowing energy to be obtained through NEFA and TG. Fat and fiber feeding could avoid insulin resistance improving the efficiency of energy utilization and performance of horses during endurance races it also could reduce excitement and increases in muscle enzymes. mU). Im Blut dieTiere waren ferner (ohne Berücksichtigung von Pferden mit klinischer Myopathie, "Rhabdomyolyse") höhere CK-und AST-Werte bei 48 km (P < 0,005), und bei REC (P = 0,002) sowie höhere Kortisolkonzentrationen (P = 0 036; 131,1 ± 10,2 ng/dl) zu beobachten als bei den im Ziel einlaufenden Pferden (Kortisol, 119.9 ± 4.7 ng/dl) Gegenüber dem Ruhewert stiegen die Plasmawerte für CK, AST, Kortisol, Glycerol, Triglyzeride und RISQI an, während für Insulin und MIRG ein Abfall zu verzeichnen war. Pferde, die mit SS und CC gefüttert wurden, hatten niedrigere RISQI-Werte (p=0,018) als die mit FF versorgtenTiere. Die MIRG-Werte waren für die FF-Gruppe lediglich tendenziell niedriger (P = 0,088) als bei den Gruppen SS und CC. Die Pferde dieser beiden Gruppen wiesen höhere Insulinwerte auf (SS 17,7 ± 1,6, CC 18,6 ± 1,8 mU/L) als die nach FF-Regime versorgten Pferde (13,6 ± 0,9 mU/L). Die Ergebnisse dieser Arbeit zeigen, dass eine Insulin Resistenz ein mit dem notwendigen Ausschluss von Pferden aus dem Wettbewerb in Zusammenhang stehender Faktor sein kann. Durch eine fett-und strukturreiche Fütterung kann, wie der Werte für die RISQI zeigen, eine Insulin Resistenz vermieden werden. Zwei Pferde wurden wegen klinischer Symptome einer Myopathie (Rhabdomyolyse) eliminiert; insgesamt zeigten vom Wettbewerb ausgeschlossene Pferde höhere Werte für muskelsensitive Enzymen bei Kilometer 27, 48 und bei REC als die unauffälligen Tiere. A...

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