Variability in concentrations of zinc in serum and feed when using zinc oxide as a supplement for the prevention of facial eczema

AIMS: To determine the variability of concentrations of Zn in feed, when used as a supplement to prevent facial eczema, and to determine the variability in concentrations of Zn in serum between cows and herds that are being supplemented with ZnO in feed, using in-shed feeders or on a feed pad.

METHODS: Sixteen commercial dairy farms in the Waikato region of New Zealand were enrolled, that were supplementing cows with ZnO in the feed using either an automatic in-shed feeder (ASF) or a feed pad (FP) using a feed-out or mixer wagon. On each farm 10 cows were selected by the farmer, that were assumed to be representative of the age and liveweight of the herd. Four hours after supplement feeding, each cow was weighed and a blood sample collected for measurement of concentrations of Zn in serum. Three samples of feed were collected from each farm for Zn analysis, from the beginning, middle and end of the feed being distributed. Levene’s test for homoscedasticity was used to analyse whether there were differences in variation of individual concentrations of Zn in serum, and in the feed, between the two feeding systems. Multivariable linear regression was used to examine associations between age, feeding method or liveweight and concentrations of Zn in serum, after accounting for the variability between farms.

RESULTS: Of the 163 cows sampled, concentrations of Zn in serum were between 20–35?µmol/L in 75/163 (46 (95% CI=38–54)%) cows; were <20?µmol/L in 71/163 (44 (95% CI=36–52)%) cows, and >35?µmol/L in 17/163 (10 (95% CI=6–16)%) cows. The variation in concentrations of Zn in serum in individual cows differed between farms (p<0.001), and the variability was greater for cows fed using a FP than ASF (p<0.001). There was no difference in the variation of concentrations of Zn in feed between the two feeding methods (p=0.54), but concentrations of Zn in serum were associated with the amount of Zn offered in feed (p=0.008).

CONCLUSIONS AND CLINICIAL RELEVENCE: There was significant variability between farms in the concentrations of Zn in the serum of cows being supplemented with ZnO in feed. Only 46% of cows sampled had concentrations of Zn between 20–35?µmol/L. Effective management of facial eczema should include monitoring Zn in the feed and in serum to ensure cows are receiving the correct dose they require.     

牧草新品种黔草1号高羊茅的选育

黔草1号高羊茅是利用贵州地方野生资源作亲本,采用改良混合选择法,经10余年的选育研究育成的新品种。该品种抗逆性强、适应性广、坪用性好、耐践踏、持续性好、绿期长,返青期比引进品种凌志提前7 d,枯黄期晚3 d;种子成熟期集中,种子平均产量比对照品种高20%以上。适应我国长江中下游低山、丘陵等地区种植,是运动场草坪、环境绿化、生态治理的优良草种。     

Genetic analysis of the maximum germination distance of Striga under Fusarium oxysporum f. sp. strigae biocontrol in sorghum

Maximum germination distance(MGD) is an important component of Striga resistance in sorghum. The objective of this study was to determine gene action influencing MGD of Striga hermonthica and Striga asiatica among selected sorghum lines treated with a biocontrol agent, Fusarium oxysporum f. sp. strigae(FOS) for effective breeding with Striga resistance, and FOS compatibility. Twelve sorghum genotypes were selected based on their Striga resistance, FOS compatibility, and superior agronomic performance. Selected genotypes were crossed using a bi-parental mating design to generate six families for genetic analysis. Agar-gel assays were used to determine low haustorium initiation factor(LHF) using the 12 parental lines, their F_1 progenies, backcross derivatives, and F_2 segregants in two sets. One set had S. hermonthica seed and the other one had S. asiatica seed. Both were treated with and without FOS. Genotypes were evaluated using a split-plot design with three replications and MGD data were recorded followed by generation mean analysis. FOS reduced MGD by 1cm under both S. hermonthica and S. asiatica infestations. Additive, dominance, and epistatic gene actions were involved in the control of MGD of the two Striga species in the evaluated populations. On average, the relative contribution of additive, additive×additive and dominance×dominance genetic effects on the MGD of S. hermonthica and S. asiatica, with FOS, were 20, 33, and 36%; and 21, 32, and 35%, respectively. Breeding methods exploiting these genetic effects may provide enhanced response to selection for Striga resistance and FOS compatibility in integrated Striga management(ISM) programmes.     

TGF-beta3 exists in bony fish

A partial nucleotide sequence of transforming growth factor-beta3 (TGF-beta3) has been isolated from the Siberian sturgeon (Acipenser baeri), rainbow trout (Oncorhynchus mykiss) and European eel (Anguilla anguilla), confirming a ubiquitous presence in the ray-finned (Actinopterygian) bony fish. The bony fish TGF-beta3 is highly conserved, with some 83-84% nucleotide identity (coding region) and 90-95% predicted amino acid identity to known homeotherm TGF-beta3's. Far lower homologies are apparent with other known TGF-beta isoforms in fish (e.g. 64-66% and 81-82% amino acid identity to trout TGF-beta 1/5 and carp TGF-beta2 respectively). Phylogenetic tree analysis showed that the fish TGF-beta3's clustered with the known homeotherm TGF-beta3's. The relatively tight clustering of TGF-beta1, TGF-beta2 and TGF-beta3 was in contrast to the TGF-beta5's, which are clearly a more heterogenous group.     

Effect of Quil A,a saponin derivative,on the response of sheep to alum precipitatedBacteroides nodosus vaccines

Alum precipitatedBacteroides nodosus vaccines prepared from two antigens with and without the saponin derivative, Quil A, did not induce adverse tissue reactions in sheep injected subcutaneously. Vaccinated, non-infected Merino sheep had higher agglutinin antibody titres when the vaccines included Quil A. Moreover, the recovery rates in vaccinated sheep affected with foot-rot were higher when the vaccines included Quil A.     

The occurrence, prevalence and transmission of Bacteroides nodosus infection in cattle

Following reports of findings of ovine foot-rot flora in the feet of cattle, a study was undertaken to determine the prevalence of Bacteroides nodosus infection in the apparently normal cattle population. We found that 34.5 to 74.2 per cent of the animals examined on different farms had B nodosus present in one or more feet. B nodosus was not the most prevalent bacterium observed in smears from cattle. Other Gram negative species including Fusiformis necrophorus and many Gram positive cocci and coccobacilli were also present. Macroscopic lesions in the interdigital skin characterised by erosion and hyperkeratosis were usually associated with the occurrence of B nodosus. B nodosus isolated from cattle induced mild interdigital dermatitis in experimental cattle and sheep and the infection was transmitted to recipient cattle and sheep under field conditions. Virulent foot-rot of sheep was not transmitted to recipient cattle in conditions where the disease spread to susceptible sheep.     

Effect of Leptin on In Vivo Goat Embryo Production

The aim of this study was to evaluate the effect of leptin administration during superovulation on in vivo goat embryo production. Ten mature does were superovulated with 133 mg follicle‐stimulating hormone (FSH) i.m. in six descending doses at 12‐h intervals. The goats received 4.8 μg/kg human recombinant leptin s.c. (leptin group, n = 5) or phosphate‐buffered saline (PBS) (control group, n = 5) with the first and second FSH doses. The does were mated and subjected to embryo collection by transcervical technique 6 days later. The total number of cells per embryo and the number of cells with fragmented DNA were assessed in selected blastocysts by combining Hoechst 33342 and terminal dUTP nick‐end labelling (TUNEL) staining. Plasma concentrations of oestradiol (E₂) and progesterone (P₄) were determined by electrochemiluminescence from the day of FSH treatment, on the day of superovulatory oestrus and on the day before embryo collection. Compared with the control group, the does that received leptin had a higher number of transferable embryos (p < 0.005), fewer embryos classified as degenerated (p < 0.001) and fewer TUNEL‐positive cells/blastocyst (p < 0.001). The number of transferable embryos was positively correlated with E₂ concentrations on day of oestrus (r = 0.562; p < 0.01) and P₄ concentrations on the day of embryo collection (r = 0.912; p < 0.001). We concluded that in vivo leptin administration during FSH treatment improved embryo quality and affected ovarian steroidogenesis in superovulated goats.     

Large-scale turbidostat culture of marine microalgae

A simple and inexpensive device is described which maintains cultures of marine microalgae at predetermined cell densities by the automatic control of harvesting and replenishment of the culture volume with fresh medium. Cultures were maintained at a range of cell densities in 80-litre internally illuminated vessels and the daily cell production yield was evaluated.Maximum yields of 0·8–1·0×10¹² cells day^?1 of Isochrysis aff. galbana Green and 0·8–1·2×10¹¹ cells day^?1 of Tetraselmis suecica (Kylin) Butch. were obtained at culture densities of 15–17×10³ cells μlitre^?1 and 19–21×10² cells μlitre^?1, respectively. Turbidostat cultures of Skeletonema costatum (Grev.) Cleve could not consistently be maintained above 5–7×10³ cells μlitre^?1.