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.     

Photochemical damage and comparative performance of superoxide dismutase and ascorbate peroxidase in sugarcane leaves exposed to paraquat-induced oxidative stress

The physiological responses of sugarcane (Saccharum officinarum L.) to oxidative stress induced by methyl viologen (paraquat) were examined with respect to photochemical activity, chlorophyll content, lipid peroxidation and superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities. Thirty-day-old sugarcane plants were sprayed with 0, 2, 4, 6 and 8 mM methyl viologen (MV). Chlorophyll fluorescence was measured after 18 h and biochemical analyses were performed after 24 and 48 h. Concentrations of MV above 2 mM caused significant damage to photosystem II (PSII) activity. Potential and effective quantum efficiency of PSII and apparent electron transport rate were greatly reduced or practically abolished. Both chlorophyll and soluble protein contents steadily decreased with MV concentrations above 2 mM after 24 h of exposure, which became more pronounced after 48 h, achieving a 3-fold decrease. Insoluble protein contents were little affected by MV. Oxidative stress induced by MV was evidenced by increases in lipid peroxidation. Specific activity of SOD increased, even after 48 h of exposure to the highest concentrations of MV, but total activity on a fresh weight basis did not change significantly. Nondenaturing PAGE assayed with H₂O₂ and KCN showed that treatment with MV did not change Cu/Zn-SOD and Mn-SOD isoform activities. In contrast, APX specific activity increased at 2 mM MV but then dropped at higher doses. Oxidative damage induced by MV was inversely related to APX activity. It is suggested that the major MV-induced oxidative damages in sugarcane leaves were related to excess H₂O₂, probably in chloroplasts, caused by an imbalance between SOD and APX activities, in which APX was a limiting step. Reduced photochemical activity allowed the early detection of the ensuing oxidative stress.     

Genotype by environment interaction for disease resistance and other important agronomic traits supporting the indication of common bean cultivars

The present work aimed to study the genotype by environment interaction for nine important agronomic traits as a support for the indication of common bean cultivars for the Southern region of Brazil, identifying cultivars that possess high adaptability/stability. We carried out 25 field trials, in the rainy and dry sowing seasons, at different locals in the states of Paraná and Santa Catarina, from 2008 to 2010. The trials included 17 cultivars. Data were obtained for agronomic traits and subjected to variance analyses, and to adaptability and stability analyses according to the Nunes method. The genotype by environment interaction is important for different agronomic traits. There is genetic variation among cultivars and it was identified a different number of superior cultivars for each trait. Considering the means and adaptability and stability scores, 88% of the cultivars were superior for rust, 53% for anthracnose, 41% for grain yield, plant architecture and cycle, 30% for fusarium wilt and lodging, and 18% for angular leaf spot and common bacterial blight. For some of these traits, like angular leaf spot, common bacterial blight, fusarium wilt and lodging, it is necessary to intensify the efforts to provide more cultivars with high resistance or tolerance level, adaptability and stability. BRS Esplendor, a black-seeded cultivar, CNFC 10431 and BRS Sublime, both carioca-seeded cultivars, presented superiority for six of nine traits, being indicated to be used in the Southern region of Brazil. Other cultivars presented advantages for fewer traits and must be used in environments which these traits present greater importance.     

Time course differential gene expression in response to porcine circovirus type 2 subclinical infection

This study was aimed at characterizing the potential differences in gene expression in piglets inoculated with Porcine circovirus type 2 (PCV2), the essential causative agent of postweaning multisystemic wasting syndrome. Seven-day-old caesarean-derived, colostrum-deprived piglets were distributed into two groups: control (n = 8) and pigs inoculated with 10^5.2 TCID₅₀ of the Burgos PCV2 isolate (n = 16). One control and three inoculated pigs were necropsied on days 1, 2, 5, and 8 post-infection (p.i.). The remaining pigs (four of each group) were sequentially bled on days 0, 7, 14, 21, and 29 p.i. (necropsy). Total RNA from the mediastinal lymph node (MLN) and lysed whole blood (LWB) samples were hybridized to Affymetrix Porcine GeneChip^®. Forty-three probes were differentially expressed (DE) in MLN samples (FDR < 0.1, fold change > 2) and were distributed into three clusters: globally down-regulated genes, and up-regulated genes at early (first week p.i.) and late (day 29 p.i.) stages of infection. In LWB samples, maximal differences were observed at day 7 p.i., with 54 probes DE between control and inoculated pigs. Main Gene Ontology biological processes assigned to up-regulated genes were related to the immune response. Six common genes were found in both types of samples, all of which belonged to the interferon signaling antiviral effector pathway. Down-regulated genes were mainly related to cell adhesion and migration in MLN, and cellular organization and biogenesis in LWB. Microarray results were validated by quantitative real-time PCR. This study provides, for the first time, the characterization of the early and late molecular events taking place in response to a subclinical PCV2 infection.     

Hydrogen radicals, nitrogen radicals, and the production of O3 in the upper troposphere

The concentrations of the hydrogen radicals OH and HO2 in the middle and upper troposphere were measured simultaneously with those of NO, O3, CO, H2O, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field. The data allow a direct examination of the processes that produce O3 in this region of the atmosphere. Comparison of the measured concentrations of OH and HO2 with calculations based on their production from water vapor, ozone, and methane demonstrate that these sources are insufficient to explain the observed radical concentrations in the upper troposphere. The photolysis of carbonyl and peroxide compounds transported to this region from the lower troposphere may provide the source of HOx required to sustain the measured abundances of these radical species. The mechanism by which NO affects the production of O3 is also illustrated by the measurements. In the upper tropospheric air masses sampled, the production rate for ozone (determined from the measured concentrations of HO2 and NO) is calculated to be about 1 part per billion by volume each day. This production rate is faster than previously thought and implies that anthropogenic activities that add NO to the upper troposphere, such as biomass burning and aviation, will lead to production of more O3 than expected.     

In situ observations of a high-pressure phase of H2O Ice

A previously unknown solid phase of H2O has been identified by its peculiar growth patterns, distinct pressure-temperature melting relations, and vibrational Raman spectra. Morphologies of ice crystals and their pressure-temperature melting relations were directly observed in a hydrothermal diamond-anvil cell for H2O bulk densities between 1203 and 1257 kilograms per cubic meter at temperatures between -10 degrees and 50 degreesC. Under these conditions, four different ice forms were observed to melt: two stable phases, ice V and ice VI, and two metastable phases, ice IV and the new ice phase. The Raman spectra and crystal morphology are consistent with a disordered anisotropic structure with some similarities to ice VI.     

Principles for Sustainable Governance of the Oceans

Pressures being exerted on the ocean ecosystems through overfishing, pollution, and environmental and climate change are increasing. Six core principles are proposed to guide governance and use of ocean resources and to promote sustainability. Examples of governance structures that embody these principles are given.     

浅谈疫病和环境

随着养殖业的发展，环境污染已逐渐成为畜牧养殖中的主要问题之一。畜禽死淘率的增高和药费支出的加大，已经提出了一个危险的信号，提示我们要加强环境的卫生管理，防止病原体污染，这是防止疫病发生的一个关键措施。