Effect of setting a maximum milking time,from peak lactation,on production,milking time and udder health

Abstract

AIM: To examine the effect of setting a maximum milking time, from peak lactation until drying-off, on production, duration of milking, and udder health of dairy cows.

METHODS: Forty cows were assigned in twin-pairs to be either milked until cups were removed at a milk flow-rate threshold of 0.35 kg/minute (Control), or until cups were removed at a milk flow-rate threshold of 0.35 kg/minute, or maximum time, whichever came first (MaxT). The maximum time was set by determining the milking time of the 70th percentile cow when ranked from fastest to slowest, irrespective of yield. The milking routine was typical of that practised on dairy farms in New Zealand, and involved no pre-milking preparation. The study began at peak lactation (68 (SD 7) days in milk; DIM) and continued for 26 weeks. Duration of milking and milk yield were measured for each milking. Composition of milk was determined from weekly herd tests, and milk quality from fortnightly somatic cell counts (SCC). Completeness of milking and teat condition were assessed during the study. The bacterial status of quarter milk samples was determined at the beginning and end of the study, and all treated cases of clinical mastitis recorded. ANOVA was used to examine the effect of treatment group on variables of interest.

RESULTS: Total milk, fat and protein yields during the study period did not differ between treatments. On average, 30.3% of the morning and 27.6% of the afternoon milkings of MaxT cows reached the maximum time at which cups were removed, and were therefore shortened. While the average milking time of the slowest-milking cow was longer for the Control compared with MaxT group in Weeks 1–18, the average milking time did not differ between treatments. There was no difference in overall SCC, and the incidence of clinical mastitis, or the percentage of infected quarters at drying-off, was similar for the MaxT and Control cows.

CONCLUSION: The results show that setting a maximum milking time can reduce the milking time of slower-milking cows in a herd without compromising overall herd production and udder health.

CLINICAL RELEVANCE: Although the numbers of cows in the study were small there was no evidence of a major increase in SCC, or subclinical or clinical mastitis when a maximum milking time was set for slower-milking cows.     

Rapid vacuolar sequestration: the horseweed glyphosate resistance mechanism

BACKGROUND: Glyphosate‐resistant (GR) weed species are now found with increasing frequency and threaten the critically important GR weed management system. RESULTS: The reported ³¹P NMR experiments on glyphosate‐sensitive (S) and glyphosate‐resistant (R) horseweed, Conyza canadensis (L.) Cronq., show significantly more accumulation of glyphosate within the R biotype vacuole. CONCLUSIONS: Selective sequestration of glyphosate into the vacuole confers the observed horseweed resistance to glyphosate. This observation represents the first clear evidence for the glyphosate resistance mechanism in C. canadensis. Copyright © 2010 Society of Chemical Industry     

Involvement of the Fas and Fas ligand in testicular germ cell apoptosis by zearalenone in rat

Zearalenone (ZEA), a nonsteroidal estrogenic mycotoxin, is known to cause testicular toxicity in animals. In the present study, the effects of ZEA on spermatogenesis and possible mechanisms involved in germ cell injury were examined in rats. Ten-week-old Sprague-Dawley rats were treated with 5 mg/kg i.p. of ZEA and euthanized 3, 6, 12, 24 or 48 h after treatment. Histopathologically, spermatogonia and spermatocytes were found to be affected selectively. They were TUNEL-positive and found to be primarily in spermatogenic stages I-VI tubules from 6 h after dosing, increasing gradually until 12 h and then gradually decreasing. Western blot analysis revealed an increase in Fas and Fas ligand (Fas-L) protein levels in the ZEA-treated rats. However, the estrogen receptor (ER)α expression was not changed during the study. Collectively, our data suggest that acute exposure of ZEA induces apoptosis in germ cells of male rats and that this toxicity of ZEA is partially mediated through modulation of Fas and Fas-L systems, though ERα may not play a significant role.     

High-Tc superconductors in the two-dimensional limit:

The free modulation of interlayer distance in a layered high-transition temperature (high-Tc) superconductor is of crucial importance not only for the study of the superconducting mechanism but also for the practical application of high-Tc superconducting materials. Two-dimensional (2D) superconductors were achieved by intercalating a long-chain organic compound into bismuth-based high-Tc cuprates. Although the intercalation of the organic chain increased the interlayer distance remarkably, to tens of angstroms, the superconducting transition temperature of the intercalate was nearly the same as that of the pristine material, suggesting the 2D nature of the high-Tc superconductivity.     

Accelerated Growth, Gigantism and Likely Sterility in Autotransgenic Triploid Mud Loach Misgurnus mizolepis

Triploidy was induced in two selected lines of autotransgenic mud Ioach Misgurnus mizolepis containing no heterospecific genetic material. Cytological evaluations, including cellular DNA content, chromosome count, and erythrocyte measurement, proved the successful induction of triploidy. Patterns of Southern blot hybridization and tissue distribution of GH mRNA in autotransgenic triploids were similar to those of diploid autotransgenics. The autotransgenic triploids also displayed growth acceleration 22–25 times that of nontransgenic diploids, although the acceleration was relatively modest when compared to their diploid transgenic counterparts (more than a 30-fold increase). Significantly improved feed conversion was observed in both autotransgenic diploids and triploids, ranging from 1.8 to 2.0 times that in nontransgenics. Autotransgenic triploids were sterile at gonadal level, evidenced by significantly retarded and abnormal gametogenesis. With the persistence of accelerated growth and enhanced feed conversion efficiency, the autotransgenic triploid mud loach may offer economic benefits to aquaculture. Total absence of heterospecific genetic material and sterility may also allay public concern regarding food safety and environmental risk of crossbreeding between transgenics and conspecific populations.     

In vivo alternative testing with zebrafish in ecotoxicology

Although rodents have previously been used in ecotoxicological studies, they are expensive, time-consuming, and are limited by strict legal restrictions. The present study used a zebrafish (Danio rerio) model and generated data that was useful for extrapolating toxicant effects in this system to that of humans. Here we treated embryos of the naive-type as well as a transiently transfected zebrafish liver cell line carrying a plasmid (phAhRE-EGFP), for comparing toxicity levels with the well-known aryl hydrocarbon receptor (AhR)-binding toxicants: 3,3'',4,4'',5-pentachlorobiphenyl (PCB126), 2,3,7,8-tetrachlorodibenzo-p-dioxin, and 3-methylcholanthrene. These toxicants induced a concentration-dependent increase in morphological disruption, indicating toxicity at early life-stages. The transient transgenic zebrafish liver cell line was sensitive enough to these toxicants to express the CYP1A1 regulated enhanced green fluorescent protein. The findings of this study demonstrated that the zebrafish in vivo model might allow for extremely rapid and reproducible toxicological profiling of early life-stage embryo development. We have also shown that the transient transgenic zebrafish liver cell line can be used for research on AhR mechanism studies.     

Enzyme-linked immunosorbent assay, single radial immunodiffusion, and indirect methods for the detection of failure of transfer of passive immunity in dairy calves

BACKGROUND: Confirmatory tests for failure of transfer of passive immunity (FTPI) in dairy calves require direct measurements of the serum immunoglobulin G concentration. Enzyme-linked immunosorbent assay (ELISA) has advantages over single radial immunodiffusion (SRID) in terms of cost and time. OBJECTIVES: To evaluate the agreement between ELISA and SRID, and to compare the diagnostic performance of ELISA with indirect methods, in the detection of FTPI in calves. ANIMALS: One hundred and fifteen dairy calves (aged 0-10 days) from 23 calf-rearing facilities. METHODS: Prospective, observational study. The agreement between SRID and ELISA was determined by the Bland-Altman method. Fixed bias (SRID - ELISA) was calculated. For comparison of the diagnostic performance of ELISA with indirect methods, sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic (ROC) curves were calculated at cut-off values of 500 and 1,000 mg/dL. RESULTS: The agreement between SRID and ELISA was 94%. Fixed bias (SRID - ELISA) was 140 +/- 364 mg/dL. The AUC and sensitivity of ELISA at the cut-off value of 1,000 mg/dL were higher than those of indirect methods (P<.004). The specificity of ELISA at the cut-off value of 1,000 mg/dL was not higher than that of indirect methods, except for serum total protein concentration assay. CONCLUSION AND CLINICAL IMPORTANCE: ELISA exhibited good diagnostic performance and good agreement with SRID. ELISA is an adequate method for both screening and confirmatory tests for FTPI in dairy calves at the cut-off value of 500 mg/dL.