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Pimelea poisoning of cattle causes distinct symptoms and frequently death, attributable to the toxin simplexin. Pimelea poisoning was induced via addition of ground Pimelea trichostachya plant to the daily feed in a three-month trial with Droughtmaster steers. The trial tested four potential mitigation treatments, namely, biochar, activated biochar, bentonite, and a bacterial inoculum, and incorporated negative and positive control groups. All treatments tested were unable to prevent the development of simplexin poisoning effects. However, steers consuming a bentonite adsorbent together with Pimelea showed lesser rates-of-decline for body weight ( P < 0.05) and four hematological parameters ( P < 0.02), compared to the positive control group fed Pimelea only. Microbiome analysis revealed that despite displaying poisoning symptoms, the rumen microbial populations of animals receiving Pimelea were very resilient, with dominant bacterial populations maintained over time. Unexpectedly, clinical edema developed in some animals up to 2 weeks after Pimelea dosing was ceased.

Background: The natural abundance of nitrogen (δ 15 N) and carbon (δ 13 C) isotopes in animal tissues are used to estimate an animal's efficiency in nitrogen utilization, and their feed conversion efficiency, especially in tropical grazing systems with prolonged protein restriction. It is postulated that selection for improving these two characteristics (δ 15 N and δ 13 C) would assist the optimisation of the adaptation in ever-changing environments, particularly in response to climate change. The aim of this study was to determine the heritability of δ 15 N and δ 13 C in the tail hair of tropically adapted beef cattle to validate their inclusion in genetic breeding programs., Methods: In total, 492 steers from two breeds, Brahman (n = 268) and Droughtmaster (n = 224) were used in this study. These steers were managed in two mixed breed contemporary groups across two years (year of weaning): steers weaned in 2019 (n = 250) and 2020 (n = 242). Samples of tail switch hair representing hair segments grown during the dry season were collected and analysed for δ 15 N and δ 13 C with isotope-ratio mass spectrometry. Heritability and variance components were estimated in a univariate multibreed (and single breed) animal model in WOMBAT and ASReml using three generations of full pedigree., Results: The estimated heritability of both traits was significantly different from 0, i.e. 0.43 ± 0.14 and 0.41 ± 0.15 for δ 15 N and δ 13 C, respectively. These traits had favourable moderate to high genetic and phenotypic correlations (- 0.78 ± 0.16 and - 0.40 ± 0.04, respectively). The study also provides informative single-breed results in spite of the limited sample size, with estimated heritability values of 0.37 ± 0.19 and 0.19 ± 0.17 for δ 15 N and δ 13 C in Brahman, and 0.36 ± 0.21 and 0.46 ± 0.22 for δ 15 N and δ 13 C in Droughtmaster, respectively., Conclusions: The findings of this study show, for the first time, that the natural abundances of both nitrogen and carbon isotopes in the tail hair in cattle may be moderately heritable. With further research and validation, tail hair isotopes can become a practical tool for the large-scale selection of more efficient cattle., (© 2024. The Author(s).)

The difficulty in selecting cattle for higher feed and nitrogen use efficiency (NUE) is an important factor contributing to poor growth and reproductive performance in dry-tropics rangelands. Therefore, the objectives were to examine the cattle variation in retaining nitrogen in a protein-deficient diet and the natural abundance of stable isotopes in body tissues as a practical alternative for the detection of more efficient cattle. In experiment 1, feed efficiency parameters were determined in 89 Brahman steers fed a protein-limiting diet for 70 days, followed by 7 days in metabolism crates for total collection of urine and faeces and calculation of nitrogen retention and NUE. The diet-animal fractionation of nitrogen isotopes (Δ 15 N) was quantified in tail hair and plasma proteins using isotope-ratio MS. There was a large variation in growth performance, feed efficiency and nitrogen losses among steers. Quantifying Δ 15 N in tail hair (Δ 15 N tail hair ) resulted in stronger correlations with feed efficiency and nitrogen metabolism parameters than when quantified in plasma proteins. Δ 15 N tail hair was positively correlated with nitrogen losses in urine (r = 0.31, P < 0.01) and faeces (r = 0.25, P = 0.04), leading to a negative correlation with NUE (r = -0.40, P < 0.01). The group of steers with lower Δ 15 N tail hair had greater feed efficiency, lower nitrogen losses, and greater NUE. In experiment 2, for evaluation of isotope fraction as a predictor of reproductive performance, 630 Brahman-crossed cows were classified for reproductive performance for 2 years. From this group, 25 cows with poor reproductive performance and 25 cows with good reproductive performance were selected. Tail hair representing 7 months of growth were segmented and analysed for carbon (δ 13 C) and nitrogen (δ 15 N) isotope enrichment. Reproductive performance was not associated with diet selection, as there was no difference in tail hair δ 13 C between groups. However, more productive cows had lower (P < 0.05) tail hair δ 15 N during the dry season, indicating differences in N metabolism and possibly lower N losses. In addition, cows with better reproductive performance and, therefore, greater nutrient demands, had similar body condition scores and a tendency (P = 0.09) for higher live weight at the end of the trial. In conclusion, the findings of the present study confirm that nitrogen isotope fractionation in tail hair can be used as a predictor of nitrogen losses, NUE, and reproductive performance of Brahman cattle on low-protein diets., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

The European Robin is a small passerine bird associated with woodlands of Eurasia and North Africa. Despite being relatively widespread and common, little is known of the species' breeding biology and genetic diversity. We used Next Generation Sequencing (NGS) to develop and characterize microsatellite markers for the European Robin, designing three multiplex panels to amplify 14 microsatellite loci. The level of polymorphism and its value for assessing parentage and genetic structure was estimated based on 119 individuals, including seven full families and 69 unrelated individuals form Poland's Białowieża Primaeval Forest and an additional location in Portugal. All markers appeared to be highly variable. Analysis at the family level confirmed a Mendelian manner of inheritance in the investigated loci. Genetic data also revealed evidence for extra-pair paternity in one family. The set of markers that we developed are proven to be valuable for analysis of the breeding biology and population genetics of the European Robin., (© 2021. The Author(s).)

The objective was to evaluate the effects of a specific strain of live yeast (LY) on growth performance, fermentation parameters, feed efficiency, and bacterial communities in the rumen of growing cattle fed low-quality hay. In experiment (exp.) 1, 12 Droughtmaster bull calves (270 ± 7.6 kg initial body weight [BW]) were blocked by BW into two groups, allocated individually in pens, and fed ad libitum Rhodes grass hay (8.4% of crude protein [CP]) and 300 g/bull of supplement (52% CP) without (Control) or with LY (8 × 109 colony-forming unit [CFU]/d Saccharomyces cerevisiae CNCM I-1077; Lallemand Inc., Montreal, Canada) for 28 d, followed by 7 d in metabolism crates. Blood and rumen fluid were collected before feeding and 4 h after feeding. In exp. 2, for assessment of growth performance, 48 Charbray steers (329 ± 20.2 kg initial BW) were separated into two blocks by initial BW and randomly allocated into 12 pens. The steers were fed Rhodes grass hay (7.3% CP) and 220 g/steer of supplement (60% CP) without or with LY (8 × 109 CFU/d) for 42 d, after a 2-wk adaptation period. In exp. 1, fiber digestibility was calculated from total fecal collection, and, in exp 2, indigestible neutral detergent fiber (NDF) was used as a marker. Inclusion of LY increased (P = 0.03) NDF intake by 8.3% in exp. 1, without affecting total tract digestibility. No changes were observed in microbial yield or in the efficiency of microbial production. There was a Treatment × Time interaction (P < 0.01) for the molar proportion of short-chain fatty acids, with LY increasing propionate before feeding. Inclusion of LY decreased rumen ammonia 4 h after feeding (P = 0.03). The addition of LY reduced rumen bacterial diversity and the intraday variation in bacterial populations. Relative populations of Firmicutes and Verrucomicrobia varied over time (P < 0.05) only within the Control group. At the genus level, the relative abundance of an unclassified bacterial genus within the order Clostridiales, a group of cellulolytic bacteria, was reduced from 0 to 4 h after feeding in the Control group (P = 0.02) but not in the LY group (P = 1.00). During exp. 2, LY tended to increase average daily gain (ADG) (P = 0.08) and feed efficiency (P = 0.10), with no effect on NDF intake or digestibility. In conclusion, S. cerevisiae CNCM I-1077 reduced the intraday variation of rumen bacteria and increased the amount of NDF digested per day. These observations could be associated with the tendency of increased ADG and feed efficiency in growing cattle fed a low-quality forage., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The aim of this study was to investigate the effects of sugarcane neutral detergent fiber digestibility (NDFD), conservation method, and concentrate level on the ruminal microbial population of steers. Eight ruminal-cannulated Nellore steers were distributed in two contemporary 4 × 4 Latin Square design with a 2 × 2 factorial arrangement of treatments. Experiment 1: diets were formulated with 60% of concentrate level, and two sugarcane genotypes (high or low NDFD) either freshly cut or as silage. Experiment 2: diets were formulated with two levels of concentrate (60 or 80%), and two sugarcane genotypes (high or low NDFD) offered as freshly cut. Each experimental period lasted for 14 d, with the last 4 d used for ruminal fluid collection. Three cellulolytic bacteria (Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens), two amylolytic (Streptococcus bovis, Ruminobacter amylophilus), and a lactate fermenting microorganism (Megasphaera elsdenii) were quantified by qPCR. Experiment 1: diets with fresh sugarcane increased the population of S. bovis, and M. elsdenii. Sugarcane with high NDFD increased F. succinogenes population only when sugarcane was offered as freshly cut. Experiment 2: increasing concentrate in the diet decreased S. bovis population, and increased R. amylophilus. Sugarcane with high NDFD increased the population of cellulolytic bacteria only at the 60% concentrate diet. Providing sugarcane with high NDFD favored the growth of fibrolytic bacteria, and this effect were dependent on the conservation method and on diet concentrate level. In addition, sucrose appears to have great effect on the composition of ruminal microflora, especially S. bovis.

The objective was to evaluate effects of neutral detergent fibre (NDF) digestibility and level of fresh sugarcane on intake, body fatness, carcass characteristics, and rumen kinetics and fermentation of beef cattle. Forty-eight Nellore young bulls were used in a complete randomized block design with a 2 × 2 factorial arrangement of treatments. Eight rumen-cannulated Nellore steers were used in a replicated 4 × 4 Latin square design. Two sugarcane genotypes divergent for stalk NDF digestibility (NDFD) were used. Experimental diets were formulated with 20 or 40% of sugarcane on a dry matter (DM) basis. High-NDFD genotype associated with the lower level of roughage in the diet promoted greater DM intake, resulting in greater body gain. Sugarcane with high-NDFD increased final body weight, hot carcass weight, and back-fat thickness. Animals receiving the genotype with high NDFD had greater rump-fat thickness only with 40% sugarcane in the diet. Animals receiving the low-NDFD genotype at 20% of the diet had lower NDF passage rate. Rumen pH was greater for diets with greater NDF content. There was greater proportion of butyrate in the rumen of animals receiving diets with greater NDF content. In conclusion, high-NDFD sugarcane increased final body and carcass weight, HCW, and fat thickness. When associated with lower inclusion of roughage in the diet, it can also increase DM intake and body weight gain of beef cattle.

Monensin and functional oils (FO) were supplemented to a high-concentrate diet abruptly fed to 12 ruminally cannulated Zebu steers to study their effects on rumen fermentation, blood metabolites, and , , and relative population. A randomized complete block design with repeated measures over time within 2 experimental periods of 21 d each was used. Treatments were a control (CTR; with no additives), FO (included at 400 mg/kg), and monensin included at 30 mg/kg (M30) or 40 mg/kg (M40). All steers were fed the same high-concentrate basal diet, which consisted of 92.25% concentrate. The first 60 h after transition showed a treatment and hour interaction for ruminal propionate proportion ( = 0.028), and no change in acetate molar proportion ( = 0.633), rumen pH ( = 0.370), and time the rumen pH remained below 5.6 ( = 0.242) were observed. The acetate:propionate ratio decreased ( = 0.020) when monensin was fed in both concentrations (2.30 for the M30 treatment and 2.32 for the M40 treatment) compared with when the CTR was fed (2.85), without being different when the FO (2.71) treatment was fed. Only the M30 treatment did not show pH below 5.2 (P=0.047) over the 60 h after the abrupt transition. Within the entire period, DMI ( = 0.008) and mean ruminal pH ( = 0.040) as well as molar proportions of propionate ( = 0.034) and valerate ( = 0.031) had significant interactions between treatment and day. Total VFA concentration was greater ( = 0.017) for the M30 (117.36 m) and CTR treatments (115.77 m) compared with the M40 treatment (105.02 m), without being different for the FO treatment (111.55 m). Treatments did not change feed behavior parameters. Blood HCO ( = 0.006) and total carbon dioxide ( = 0.003) were greater for the M30 (27.8 and 29.3 mmol/L, respectively) and FO treatments (28.3 and 29.7 mmol/L, respectively) compared with the CTR treatment (25.7 and 26.9 mmol/L, respectively). ( < 0.0001) and ( < 0.0001) decreased their population throughout days, whereas ( = 0.026) increased its population. Independent of ciliated protozoa genera, the greatest ( < 0.0001) protozoa counts were observed for the CTR treatment (52.7 × 10/mL), intermediate for the FO treatment (35.3 x10/mL), and least for steers fed monensin in both concentrations (15 × 10/mL for the M30 treatment and 14 × 10/mL for the M40 treatment). Feed additives had different effects to reduce the subacute acidosis. The use of the FO and M40 treatments did not change most of the rumen fermentation variables, especially in the first week after abrupt transition, when the M30 treatment provided higher protection against acidosis.

The aim of this study was to develop and evaluate a real-time quantitative PCR (qPCR)-based method to detect and quantify Staphylococcus aureus in bronopol-preserved milk samples from subclinical intramammary infections (IMI). Serial dilutions of milk artificially inoculated with Staph. aureus ATCC 29213 were used to establish a standard curve (cfu/mL) of the qPCR assay targeting the Staph. aureus thermonuclease-encoding gene nuc according to the strain plate count. The analytical sensitivity, specificity, and repeatability of the qPCR assay were determined. A total of 60 milk samples, collected from mammary quarters without abnormal appearance and with positive isolation of Staph. aureus, were submitted to both the qPCR protocol and Staph. aureus plate counting and results from both methods were compared. Staphylococcus aureus from bronopol-preserved, subclinical IMI milk samples were not accurately enumerated by qPCR compared with plate counting of the nonpreserved, raw milk sample. The detection limit of the qPCR protocol of inoculated Staph. aureus ATCC 29213 in bronopol-preserved milk samples was 1.04 × 10(1) cfu/mL. The qPCR protocol can be a high-throughput and rapid diagnostic assay to accurately detect Staph. aureus IMI from bronopol-preserved milk samples compared with a traditional culturing method. However, the proposed qPCR protocol is not accurate for counting of Staph. aureus in bronopol-preserved milk samples from naturally infected mammary glands., (Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)