Effect of increasing monensin sodium levels in diets with virginiamycin on the finishing of Nellore cattle

This study evaluated the effect of increasing levels of monensin sodium (MON) in diets with virginiamycin (VM) on the finishing of feedlot cattle. Two hundred and eighty intact male Nellore cattle (348 ± 32 kg body weight, 22 months) received one of the following five diets: control diet (without additives); diet containing VM (25 mg per kg dry matter) combined with 0 (MON0), 10 (MON10), 20 (MON20) or 30 (MON30) mg MON per kg dry matter. During adaptation (28 days), the MON0 diet increased dietary net energy for maintenance and gain compared to the control diet (P = 0.04). The combination of additives linearly reduced dry matter intake, body weight and average daily gain (P < 0.01). Considering the total study period (110 days), there was a trend of greater net energy intake for maintenance (P = 0.09) and hot carcass weight (P = 0.06) for animals fed MON0 compared to the control diet. The combination of additives linearly reduced dry matter intake (P = 0.04) and linearly increased gain : feed and dietary net energy for maintenance and gain (P < 0.01). The combination of VM with MON at a dose of 30 mg/kg dry matter is recommended for Nellore feedlot cattle because it improves the efficiency of energy utilization.     

Cardiopulmonary effects of reverse Trendelenburg position at 5° and 10° in sevoflurane-anesthetized steers

Objective

To assess the cardiopulmonary effects caused by reverse Trendelenburg position (RTP) at 5° and 10° in sevoflurane-anesthetized yearling steers.

Testicular Structure and Seminal Pathway in the Yellowtail Tetra Astyanax altiparanae (Characiforms: Characidae)

This study aimed to describe testicular and its main ducts structure in the yellowtail tetra Astyanax altiparanae, contributing to the knowledge of the region in which semen is produced, storage and released, focusing mainly on the dynamic of germinal epithelium and Sertoli cells during germ cell maturation. Ten sexually mature male A. altiparanae had their testes processed according to the routine protocols to optical microscopy. Moreover, spermatic ducts and tubular compartment of the testes of three specimens were perfused with vinyl resin for gross anatomy and scanning electron microscopy. Astyanax altiparanae testes are paired organs, separated for most of their extension, joining posteriorly in a spermatic duct formed by a squamous simple epithelium. Seminiferous compartment presents anastomosing tubular type organisation, and spermatogonia spread along its extent. Spermatogenesis is of cystic type, and there is no main testicular duct. Spermatogenesis develops in ‘waves’, from posterior to anterior part of the gonad. Thus, while sperm is storage posteriorly, spermatogenesis keeps maturing germ cells anteriorly, making the germinal epithelium very dynamic, holding Sertoli cells that change their function as a cystic envelope to produce secretions of the seminal fluid and store sperm. Such kind of development is thought to be responsible by the high prolificacy of this species.     

Genetic diversity of the root‐knot nematode Meloidogyne enterolobii and development of a SCAR marker for this guava‐damaging species

The objectives of this work were to evaluate the genetic variability of Meloidogyne enterolobii by molecular markers, and develop species‐specific molecular markers for application in detection. Sixteen M. enterolobii isolates from different geographical regions (Brazil and other countries) and hosts were used in this study. The identification and purification of the populations were carried out based on isoenzyme phenotype. The DNA amplification of the intergenic region (IGS) of the rDNA and of the region between the cytochrome oxidase subunit II (COII) and 16S rRNA genes (mtDNA) produced specific fragments of the expected size for this nematode, i.e. 780 and 705 bp, respectively. Intraspecific variability among the isolates was evaluated with three different neutral molecular markers: AFLP, ISSR and RAPD. The results showed a low level of diversity among the isolates tested, indicating that M. enterolobii is a genetically homogeneous root‐knot nematode species. The RAPD method allowed the identification of a species‐specific RAPD fragment for M. enterolobii. This fragment was cloned and sequenced, and from the sequence obtained, a set of primers was designed and tested. The amplification of a 520‐bp‐long fragment occurred only for the 16 isolates of M. enterolobii and not for the 10 other Meloidogyne species tested. In addition, positive detection was achieved in a single individual female, egg‐mass and second stage juvenile of this nematode. This SCAR species‐specific marker for M. enterolobii represents a new molecular tool to be used in the detection of this nematode from field samples and as a routine diagnostic test for quarantine devices .     

Virulence genes and plasmid profiles in Rhodococcus equi isolates from domestic pigs and wild boars (Sus scrofa) in Brazil

The virulence genes and plasmid profiles of 23 Rhodococcus equi isolates from 258 lymph nodes from domestic pigs (129 nodes with lesions and 129 without lesions) and 120 lymph nodes from slaughtered wild boars (60 nodes with lesions and 60 without) were characterized. R. equi was obtained from 19 lymph nodes of domestic pigs, 17 with, and two without lesions, and from four lymph nodes with lesions, from wild boars. The 23 isolates were tested for the presence of vapA and vapB genes, responsible for the 15–17 and 20 kDa virulence-associated proteins, respectively, by PCR in order to characterize as virulent (VapA), intermediately virulent (VapB) and avirulent. Plasmid DNAs were isolated and analyzed by digestion with restriction endonucleases to estimate size and compare their polymorphisms. Of the 19 domestic pigs strains, seven (36.8%) were avirulent and 12 (63.2%) were intermediately virulent, with the intermediately virulent isolates being plasmid types 8 (8 isolates), 10 (2 isolates), 1 (1 isolate) and 29 (1 isolate). The plasmid type of four strains isolated from wild boars was also intermediately virulent type 8. None of the domestic pigs and wild boar isolates showed the vapA gene. These findings demonstrate a high occurrence of plasmid type 8 in isolates from pigs and wild boars, and the similarity of plasmid types in the domestic pigs, wild boars and human isolates in Brazil.     

Acaricidal properties of the essential oil and precocene II obtained from Calea serrata (Asteraceae) on the cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

Calea serrata Less. (Asteraceae), an endemic species of south Brazil known as "quebra-tudo", is used in Afro-Brazilian religious rituals and in folk medicine for treating liver disorders. Phytochemical studies of the n-hexane extract of this plant demonstrated the presence of precocene II, a benzopyran derivative known for its insecticidal activity. The aim of this work was to isolate this benzopyran and determine the chemical composition of the essential oil of C. serrata and further to evaluate the acaricidal activity of the essential oil and precocene II against the larvae of Rhipicephalus (Boophilus) microplus. The LC(99.9) and LC(50) values obtained with the oil, which presents precocene II and sesquiterpenes, were 3.94 μL/mL and 0.28 μL/mL, respectively. For precocene II this values were 4.25mg/mL and 1.78 mg/mL, respectively. The results indicate a synergistic interaction between the components of the oil and precocene II.     

Introduction and elimination of Bovine Viral Diarrhoea Virus in a commercial beef herd: a case study

Routine Bovine Viral Diarrhoea Virus (BVDV) monitoring of a commercial beef herd in southern New South Wales over a 10-year period provided an opportunity to assess the impact of the introduction of BVDV on that herd. BVDV antibody testing provided strong evidence that the herd was initially free of BVDV (2009–2011). Testing from 2012 suggested BVDV had been introduced into the herd and this was confirmed in 2015 with the identification of persistently infected (PI) animals. Having become established in the herd, the owners then set out to eliminate BVDV from the herd. Antigen testing aimed at identifying PI animals revealed BVDV was already absent from the herd. Subsequent antibody testing confirmed that the herd was now free from BVDV. Despite the incursion of BVDV in this herd, there was little measurable impact on reproductive performance (pregnancy rates), although suspected increased calf losses from birth to calf marking were reported. This is the first time such self-clearance has been documented as part of a longitudinal study under Australian conditions.     

Calcium salts of fatty acids with varying fatty acid profiles in diets of feedlot-finished Bos indicus bulls: impacts on intake,digestibility, performance,and carcass and meat characteristics

We hypothesized that the inclusion of calcium salts of fatty acid (CSFA) into the diets and the fatty acid (FA) profile of the supplements would impact performance and meat characteristics of Bos indicus bulls. Hence, the objective was to evaluate the effects of CSFA profiles on intake, body weight (BW), carcass, and meat characteristics of feedlot-finished B indicus bulls. Fifty-three Nellore bulls [initial BW 315 ± 5.9 kg and 20 ± 2 mo] were used. At the beginning, 6 bulls were randomly chosen and slaughtered for determination of their BW composition, and the remaining 47 bulls were evaluated during a 140-d experimental period. The bulls were placed in individual pens, blocked according to initial BW and randomly allocated to 1 of the 3 following treatments: (1) control diet containing sugarcane bagasse, ground corn, citrus pulp, peanut meal, and mineral–vitamin mix (CON), (2) CON with the addition of 3.3% of CSFA from soybean oil (CSO), or (3) CON with the addition of a mixture of 3.3% of CSFA from palm, soybean, and cottonseed oils (CPSCO). Diets were offered ad libitum and formulated to be isonitrogenous. Bulls supplemented with CSFA had a greater (P < 0.01) final BW, dry matter intake, average daily gain (ADG), feed efficiency (FE), and FA intake vs. CON. Among carcass parameters, CSFA-supplemented bulls had greater (P < 0.01) carcass ether extract concentration vs. CON bulls. When the CSFA profile was evaluated (CSO vs. CPSCO), CPSCO bulls had a better (P ≤ 0.03) FE, carcass ADG, and hot carcass weight (HCW) vs. CSO bulls. The FA intakes differed among CSFA treatments, as the total saturated, palmitic, and oleic FA intakes were greater for CPSCO (P < 0.01), whereas lower intakes of total unsaturated and polyunsaturated FA (P < 0.01) were observed for CPSCO vs. CSO. Samples from the Longissimus muscle contained greater palmitoleic (P = 0.01) and reduced linoleic (P = 0.02) FA concentrations in CSFA-supplemented bulls vs. CON bulls. In agreement with the FA intakes, CPSCO-supplemented bulls had a greater (P ≤ 0.05) unsaturated FA concentration vs. CSO in Longissimus muscle. In summary, CSFA supplementation improved the performance of finishing B. indicus bulls vs. CON. Moreover, the inclusion of CSFA from palm, soybean, and cottonseed oil benefited the FE, carcass ADG, and HCW compared with the inclusion of CSFA from soybean oil, demonstrating the potential of specific FA for improving the performance and meat quality of B. indicus bulls.     

Combinations of cactus pear with different roughage sources on the production,chemical composition,and milk fatty acid profile of F1 Holstein/Zebu cows

Tropical Animal Health and Production - The qualities of food, mainly of animal origin, have always been of concern to consumers. It is known that the composition of animals’ diets can...