Influence of different supplements and sugarcane (Saccharum officinarum L.) cultivars on intake, digestible variables and methane production of dairy heifers under tropical conditions

The sulphur hexafluoride (SF(6)) gas tracer method was used to measure methane (CH(4)) production of crossbred (3/4 Holstein x Zebu) dairy heifers fed two types of sugarcane (Saccharum officinarum L.; cultivar IAC-862480 (CC1) or cultivar IAC-873184 (CC2)) and supplemented with urea or concentrate. The study was performed at Embrapa Southeast Cattle, S?o Carlos, SP, Brazil, using a completely randomised design. Differences between treatments were significant for digestibility of dry matter, organic matter and energy. When animals were supplemented with urea differences between sugarcane cultivars did occur for NDF consumption, but not for daily methane production. This suggest that variation in chemical composition of sugarcane did not affect bovine ruminal CH(4) emissions. Concentrate inclusion in animal diet increased digestible organic matter intake, improving the nutrient intake by animals, but did not reduce CH(4) production expressed as a percentage of gross energy intake.     

Differentially expressed genes identified through RNA‐seq with extreme values of principal components for beef fatty acid in Nelore cattle

The aim of this study was to identify differentially expressed genes (DEG) in the Longissimus thoracis muscle of Nelore cattle related to fatty acid (FA) profile through RNA sequencing and principal component analysis (PCA). Two groups of 10 animals each were selected containing PC1 and PC2 extreme DEG values (HIGH × LOW) for each FA group. The intramuscular fat (IMF) was compared between cluster groups by ANOVA, and only the sum of monounsaturated FA (MUFA) and ω3 showed significant differences (p < .05). Interestingly, the highest percentage (95%) of phenotypic variation explained by the sum of the first two PC was observed for ω3, which also displayed the lowest number of DEG (n = 1). The lowest percentage (59%) was observed for MUFA, which also revealed the largest number of DEG (n = 66). Since only MUFA and ω3 exhibited significant differences between cluster groups, we can conclude that the differences observed for the remaining groups are not due to the percentage of IMF. Several genes that have been previously associated with meat quality and FA traits were identified as DEG in this study. The functional analysis revealed one KEGG pathway and eight GO terms as significant (p < .05), in which we highlighted the purine metabolism, glycolytic process, adenosine triphosphate binding and bone development. These results strongly contribute to the knowledge of the biological mechanisms involved in meat FA profile of Nelore cattle.     

Effects of low and high calcium intake prepartum on calcium mobilization rate around parturition in dairy cows

Forty-one dairy cows were fed a low (LCa-13 g/d) and a high (HCa-83.5 g/d) calcium ration in the 8 weeks prior to parturition and the effect on the Ca mobilization rate around parturition was studied. Plasma Ca values were stable in the LCa group around parturition. In the older cows of the HCa group a very slight decrease in the mean plasma Ca was observed: 2.58 mmol/l at 12-36 h ante partum decreased to 2.38 mmol/l at parturition. Hypocalcaemia, which commonly occurs around parturition, did not occur in 40 of the cows. A subclinical hypocalcaemia (1.8 mmol/l) occurred in one cow (parity 10) from the HCa group. To assess the efficiency of Ca mobilization, a severe hypocalcaemia (1.0 mmol/l) with clinical signs was induced by means of Na2EDTA infusion (0.90 mmol/min), starting at 10 h post-partum. The older cows in the LCa group required more Na2EDTA than those in the HCa group. Higher urinary hydroxyproline excretion in the week before parturition in the LCa than in the HCa group suggested a higher bone turnover. Plasma PTH levels around parturition were not significantly different between the groups. The amount of colostrum milked out in the first 10 h post-partum did not influence Ca homeostasis around parturition. The results contradict those of many other experiments in which hypocalcaemia was observed in cows ingesting high levels of Ca. It is concluded that the restricted feed intake prepartum possibly had a favourable effect on Ca homeostasis.     

Shiga toxin-producing Escherichia coli O157:H7 from extensive cattle of the fighting bulls breed

Shiga toxin-producing Escherichia coli (STEC) O157:H7 represents a major public health concern worldwide, with cattle recognized as their main natural reservoir. The aim of this work was to determine the prevalence and the pheno-genotypic characteristics of STEC O157:H7 in a herd with 268 cattle of the fighting bulls breed (De Lidia breed) managed under extensive conditions in the South-West of Spain. Rectal-anal swabs of all animals were collected and examined for STEC O157:H7 by performing an immunomagnetic concentration and separation procedure combined with PCR, and the resulting isolates were characterized by both phenotypic and genotypic methods. Overall, STEC O157:H7 was isolated from seven animals (2.6%) in the herd. The PCR procedure indicated that all seven isolates displayed stx₂, eae-γ1, ehxA, O157 rfbE, and fliCh7 genes. They belonged to phage types 4 (one isolate) and 42 (two isolates), and four isolates reacted with typing phages but did not conform to a recognized pattern. Among the seven isolates there were five indistinguishable PFGE patterns and other two which differed only in ?2 restriction fragments, supporting the existence of horizontal transmission among animals in the herd. The present study demonstrates that cattle managed under extensive conditions in Spain can excrete STEC O157:H7 with their faeces. To our knowledge this is the first isolation of this pathogen from De Lidia cattle.     

Shiga toxin-producing Escherichia coli (STEC) isolated from healthy dairy cattle in southern Brazil

Over a period of 1 year, the production of verotoxin was investigated in 1127 Escherichia coli isolated from 243 dairy cattle from 60 small farms in southern Brazil. Vero cell assay was used to detect toxins in culture supernatants from E. coli isolated from bovine feces. Shiga toxin-producing E. coli (STEC) detection rates were 95% (57 of 60) for farms and 49% (119 of 243) for cattle. Prevalence of STEC-positive cattle in the farms ranged from 0 to 100%. Ninety-six percent (315 of 327) of the STEC isolates did not react in the panel of sera used for typing. Twelve isolates, all non-motile, belonged to serogroups previously associated with human diseases, and 67% (8 of 12) were of only two serotypes (O91:H- and sorbitol-fermenting O157:H-). These results indicate that dairy cattle from the region surveyed may be a source of STEC potentially pathogenic for humans.     

Disseminated pythiosis in three horses

Three cases of equine subcutaneous pythiosis with dissemination to the internal organs were investigated. The subcutaneous lesions were observed on the mammary gland, nostrils and limbs of the infected horses. Histopathological analysis of the infected tissues revealed a strong eosinophilic reaction, with macrophages, mast cells and giant cells. Sparsely septated hyphal filaments of 4-6 microm diameter were identified in the center of the eosinophilic areas. Specific fluorescent antibody against Pythium insidiosum confirmed the hyphae in the infected tissues in three examined horses. In one of the three cases, the DNA sequences amplified from the infected subcutaneous tissues and internal organs, revealed that P. insidiosum's 18S SSU rDNA amplicons shared 100% identity with those sequences deposit in GenBank. This is the first report confirming by immunochemical and genetic techniques that P. insidiosum can disseminated from superficial to deep structures.     

Hepatozoon spp.: report of some cases in dogs in Brasília, Brazil

Canine hepatozoonosis is a disease caused by the tick-borne protozoan Hepatozoon spp. It has been reported in the United States, southern Europe, the Middle East, Africa and the Far East. In Brazil, canine hepatozoonosis is an emerging protozoal tick-borne disease, and is characterized by distinct clinical signs. The objective of this study was to analyze the laboratory findings of some hepatozoonosis cases in dogs in Brasília, Brazil, and their clinical signs. The animals of this experiment showed low parasitemia, similar to H. americanum, but the clinical signs presented were similar to H. canis. According to our observations and in agreement with O'Dwyer et al. [Vet. Parasitol. 94 (2001) 143], the Brazilian Hepatozoon appears more to resemble the species found in the eastern Hemisphere than with H. americanum of North America, or could be caused by a new species. Our data revealed that hepatozoonosis could be considered endemic in Brasília.