Dairy Cattle Production Systems Research Articles

Tipologia de sistemas de produção leiteiros baseado nas características produtivas e de manejo na Região Oeste do Paraná

<p>A produção de leite no Brasil é de natureza complexa, pois depende de uma base constituída de elevado número de produtores de baixa escala de produção e grande diversidade de estratégias. Nos últimos anos, essa cadeia produtiva tem sofrido consideráveis modificações estruturais, aumentando a necessidade do conhecimento e caracterização da atividade. Desta forma, o objetivo proposto neste estudo foi caracterizar propriedades rurais segundo aspectos produtivos a fim de identificar os diferentes sistemas de produção de bovinos leiteiros do Oeste do Paraná. Para tanto, foram realizadas 735 entrevistas através de questionários semiestruturados, com produtores de leite, utilizando um questionário guia referente às práticas de manejo da diversidade dos sistemas de produção. Os dados foram tabulados e tratados no programa estatístico <em>SPSS-v.18, </em>utilizou-se a análise de correspondências múltiplas – ACM e análise de conglomerados (<em>cluster hierárquico</em>). As duas primeiras dimensões agruparam 71,9% da inércia, sendo a DIM1 49,4% e a DIM2 22,5%. Utilizando a análise de cluster, formaram-se cinco grupos distintos e homogêneos (G1, G2, G3, G4 e G5) de sistemas de produção. Esses sistemas tinham em comum serem propriedades de pequeno porte e de apresentarem em sua maioria mão-de-obra familiar. Conclui-se que existem diferentes grupos de produtores de leite no município, com relação às características dos sistemas de produção no que diz respeito à estrutura da propriedade, plantel e maneira como os produtores mobilizam e atuam sobre os fatores de produção, a tipologia realizada a partir dessas características se mostra uma ferramenta útil na ação da assistência técnica e na definição de estratégias por parte da indústria.</p><p><strong> </strong></p>

Nutritional, technological and managerial parameters for precision feeding to enhance feed nutrient utilization and productivity in different dairy cattle production systems.

Abstract Increased future demand of animal products as well as competition between food, feed and fuel, require efficient utilization of feed resources to strengthen environmental, economic and social sustainability of livestock systems. The objective of this review is to summarize current knowledge on precision feeding (PF) and the relevance of PF approaches in dairy cattle production systems in developing countries. The concept of PF aims at achieving balanced nutrition (matching animal requirements with nutrient supply, preferably from locally available feed resources) to improve animal productivity and to reduce both the cost of production and environmental pollution. In addition to the supply of proper amounts of nutrients to the dairy cow using various methodologies and tools, approaches that enhance overall nutrient digestion and availability to the animal are also discussed as an integral part of PF. These approaches involve improved analyses of feed ingredients, nutrient requirement determination, formulation of a balanced ration, individual feeding, optimization of rumen and post rumen digestion, and optimization of metabolism of absorbed amino acids and other nutrients. Based on identified and analysed PF approaches, processing and treatment of forage, including conservation through ensiling, is promising to improve feed intake and productivity of the cow and to reduce excretion of environmental pollutants per unit milk. Experiments with rumen protected nutrients for both fat and protein gave a wide range of results. Inconsistent effects of the use of enzymes such as cellulases and xylanases on feed efficiency have been observed. Plant extracts need more research to get tangible results but have a broad scale of potential (indirect) advantages on production and health. Similarly more research is needed for probiotics and acidifiers, which have shown inconsistent results. Medicinal or hormonal approaches have proven to be effective in animal performance and feed efficiency. Feeding concepts, such as ration balancing programmes or the use of feed blocks, resulted in improved feed efficiency and substantially increased farmer income. In view of large variation in forage quality, rapid determination of nutrient composition of forage on site is indispensable in PF of dairy cattle. The relevance of application of the elaborate approaches for intensive, mixed crop-livestock, mixed extensive and extensive systems have been discussed. The focus of PF in developing countries should be on using feed resources that do not compete with human food, and in amounts that meet the nutrient requirements for production from the targeted animal. Policy and institutional building options are needed to realize the potential of PF for sustainable dairy production systems.

Dairy production system type and critical points of contamination

Current milk production includes a large diversity between systems, which generates difficulties in defining a microbiological standard. The adapted practical and hygienic-sanitary management methods are diverse and introduce great complexity into the production systems. Based on this scenario, the objective of this study was to evaluate the types of dairy production systems of western Parana and to quantify Staphylococcus sp in three critical points in the dairy cattle production systems: the milking machines, milkers’ hands, the cooling tanks and raw milk. A total of 35 samples of refrigerated raw milk were collected, and a questionnaire referring to hygienic and sanitary management was administered. All of the data were collected during the period from September to October 2012 and involved 35 properties in the municipality of Marechal Cândido Rondon – PR. From these data, five groups were formed based on cluster analysis (CHA). The multiple correspondence analysis (MCA) presented in the first two dimensions, CP1 (81.43%) and CP2 (36.87%), showed the relevance of the variables used, which are sanitary and production management methods, and contamination and control of mastitis, respectively (CP1 and CP2). We found average contamination with 9.9 x 101 CFU/cm2, 2.2x104 CFU/cm2, 28 CFU/ cm2 and 3.8x103 CFU/mL; for milking machines, milkers’ hands, cooling tanks and milk, respectively. The results reveal the presence of staphylococcal agent in dairy production systems regardless of the adopted hygiene and health management protocols. The guidance, planning and adaptation of hygiene and health management systems can significantly improve the microbiological quality of the milk produced, both qualitatively and quantitatively

Economic and Biological Values for Pasture-Based Dairy Cattle Production Systems and their Application in Genetic Improvement in the Tropics

Economic and biological values for milk yield (MY), milk butter fat (FY), daily gain (DG), weaning weight (WWT), mature live weight (MLW), calving interval (CI), pre-weaning survival rate (PreSR), post-weaning survival rate (PostSR), age at first calving (AFC), and productive life time (PLT) were estimated under fixed herd (FH) and pasture (FP) production circumstances assuming milk marketing based on volume, and volume and butter fat. Further, economic values were estimated involving risk using the Arrow Pratt coefficients at two levels. For the former economic values for the traits ranged from KSh. -17.246 to 100.536 while the biological values ranged between -1.29 to 0.791. Economic values with higher Arrow-Prat coefficient of absolute risk aversion (λ=0.02) were lower than those reported under λ=0.0001 indicating that the uncertainty of the future market is important and should be considered during the estimation of economic values. Genetic improvements targeting MY and growth traits would be recommended to production system with unlimited feed supply for profit maximization. However, since dairy production systems in the tropics are characterised by feed scarcity, fixing the herd and concentrating on genetically improved animals would result to more profitability than increasing animal populations.

Feed and manure use in low-N-input and high-N-input dairy cattle production systems

In most parts of Sub-Saharan Africa fertilizers and feeds are costly, not readily available and used sparingly in agricultural production. In many parts of Western Europe, North America, and Oceania fertilizers and feeds are relatively inexpensive, readily available and used abundantly to maximize profitable agricultural production. A case study, dairy systems approach was used to illustrate how differences in feed and manure management in a low-N-input dairy cattle system (Niger, West Africa) and a high-N-input dairy production system (Wisconsin, USA) impact agricultural production and environmental N loss. In Niger, an additional daily feed N intake of 114 g per dairy animal unit (AU, 1000 kg live weight) could increase annual milk production from 560 to 1320 kg AU−1, and the additional manure N could greatly increase millet production. In Wisconsin, reductions in daily feed N intake of 100 g AU−1 would not greatly impact milk production but decrease urinary N excretion by 25% and ammonia and nitrous oxide emissions from manure by 18% to 30%. In Niger, compared to the practice of housing livestock and applying dung only onto fields, corralling cattle or sheep on cropland (to capture urinary N) increased millet yields by 25% to 95%. The additional millet grain due to dung applications or corralling would satisfy the annual food grain requirements of 2–5 persons; the additional forage would provide 120–300 more days of feed for a typical head of cattle; and 850 to 1600 kg ha−1 more biomass would be available for soil conservation. In Wisconsin, compared to application of barn manure only, corralling heifers in fields increased forage production by only 8% to 11%. The application of barn manure or corralling increased forage production by 20% to 70%. This additional forage would provide 350–580 more days of feed for a typical dairy heifer. Study results demonstrate how different approaches to feed and manure management in low-N-input and high-N-input dairy cattle systems impact milk production, manure N excretion, manure N capture, N recycling and environmental N loss.

Estimating farm-gate ammonia emissions from major animal production systems in China

Ammonia (NH3) emissions from livestock production in China are an important contributor to the global NH3 budget. In this study, by estimating total nitrogen (N) intake based on herd structures and excreted N, a mass balance model was used to estimate NH3 losses from animal housing and manure storage facilities of dairy cattle, beef cattle, pigs, broiler and layer productions within animal farm gate and their corresponding NH3 emission intensities on the basis of animal products, N and protein in animal products. In 2009, NH3 emissions from pigs, layers, beef and dairy cattle and broiler production systems in China were 1.23, 0.52, 0.24, 0.21 and 0.09 million tons, respectively. The NH3 emission intensities were 26.6 g NH3–N kg−1 of pork, 28.1 g NH3–N kg−1 of layer eggs, 39.4 g NH3–N kg−1 of beef meat, 6.0 g NH3–N kg−1 of dairy milk and 4.6 g NH3–N kg−1 of chicken meat, or 1260 (pigs), 1514 (layers), 1297 (beef), 1107 (dairy) and 123 g NH3–N (broilers) kg−1 N in animal products. Of the sectors of NH3 emission, manure storage facilities and farmyard manure (FYM) in animal housing were the major contributors to the total NH3 emissions except for layers; housing emissions from slurry were also major contributors for dairy and pig production.

Breeding strategies to reduce environmental footprint in dairy cattle

Animal breeding should be considered as a permanent and cumulative approach to reducing the environmental footprint of dairy cattle production systems within an overall national and global mitigation strategy. Current international dairy cattle breeding goals do not explicitly include environmental traits, but observed improvements in milk production and both fertility and longevity contribute substantially to improving the environmental footprint relative to output. Ideally, however, environmental related traits, most notably greenhouse gas emissions and nitrogen excretion, should be explicitly included in national breeding goals with their own economic weight. Access to routine phenotypic observations for the environmental traits or other information including genomic information or information on heritable correlated traits is required for inclusion in the selection index. There is, however, a considerable paucity of information on the genetic parameters for, in particular, greenhouse gas emissions in dairy cattle; these parameters include genetic variance estimates, as well as genetic and phenotypic (co)variances with other performance traits. Large studies with well phenotyped animals across a range of environments are needed to estimate such parameters and also investigate the extent, if any, of genotype-by-environment interactions across contrasting environments. Considerable genetic variation in milk urea nitrogen, as a proxy for nitrogen excretion in the urine, exist and suggest that breeding programmes to improve nitrogen use efficiency will be fruitful. However, because of the antagonistic genetic correlations between milk urea nitrogen and milk production, genetic gain in milk yield is expected to be compromised within a breeding goal that includes milk urea nitrogen.

MODELOS DE AJUSTE PARA CURVAS DE LACTACIÓN DE VACAS EN CRIANZA INTENSIVA EN LA CUENCA DE LIMA

The description of lactation curves by mathematical models could be an effective tool for management decisions in dairy cattle production systems. In this study the comparative fit of three models: negative exponential (í = (â0e-â1x), incomplete gamma (í = â0xâ1e-â2x) and fifth order polynomial (í = â0 + â1x + ... +â5x5) was evaluated both between and within lactations using 8,763 milk yield records from 770 lactations for the first two models, and 7,228 records from 647 lactations for the third model. Milk yield records included the period 1997-2001 and were collected from five dairy farms located in Lima. The models were compared on the basis of the adjusted multiple coefficient of determination (R2 aj), the residual standard errors (EER), the standard errors of the predicted yield on day 305 (EE305), and the residual scatter plots. Additionally, the effect of parity, calving season and the 1998 El Niño phenomenon (FEN) on the basic and derived parameters of the models were estimated using general lineal models. In terms of fitness, the models ranked fifth order polynomial > incomplete gamma > negative exponential both between and within lactations. However, the fifth order polynomial model had several shortcomings like higher EE305, a tendency of overestimate late lactation yields, and a requirement of a minimum number of records. These left incomplete gamma as the model of choice, being capable to explain 72% of the yield variation within lactations and having an EE305 of only 3.3 kg. Parity and calving season affected significantly most of the basic and derived parameters of the models, whereas the FEN only affected the b0 parameter of the exponential negative and the peak yield predicted by the incomplete gamma model. All of the three mentioned factors had significant effect on the total yield predicted for a 305 day-lactation.

Inferring Upon Heterogeneous Associations in Dairy Cattle Performance Using a Bivariate Hierarchical Model

Multivariate hierarchical Bayesian models provide a flexible framework for comprehensive study of biological systems with more than one outcome. Recent methodological developments facilitate modeling of heterogeneous associations between outcomes by specifying a linear mixed model on (co)variances at different levels of the data structure. Motivated by previous evidence for heterogeneous correlations in animal agriculture, we apply the proposed hierarchical Bayesian models to study the nature of the correlations between key performance outcomes in dairy cattle production systems, namely milk yield and reproduction. That is, the association between these outcomes might depend upon various fixed and random effect sources of heterogeneity both at the individual cow (residual) level as well as the herd (cluster) level. We thus propose a sequential modeling approach based on the deviance information criterion to select relevant explanatory variables on both types of associations. Furthermore, we extend the proposed methodology to accommodate right-censored outcomes, as common for dairy reproduction data, and use it to analyze field data from the Michigan dairy industry. The nature of the associations between milk production and reproduction in dairy cattle was inferred to be strongly heterogeneous and driven by multiple farm management practices and herd attributes, as well as by random clustering effects, at both cow and herd levels, thereby suggesting potential between-herd and within-herd intervention strategies to optimize performance of dairy production systems. Supplementary materials are available online.

A review of whole farm systems models of greenhouse gas emissions from beef and dairy cattle production systems

To comply with the United Nations Framework Convention on Climate Change (UNFCCC) greenhouse gas (GHG) emissions reporting requirements, the Intergovernmental Panel on Climate Change (IPCC) developed guidelines for calculating national GHG inventories in a consistent and standard framework. Although appropriate for national level accounting purposes, IPCC methodologies lack the farm level resolution and holistic approach required for whole farm systems analysis. Thus, whole farm systems modelling is widely used for farm level analysis. A review of 31 published whole farm modelling studies of GHG emissions from beef and dairy cattle production systems indicated a number of important outcomes. For example, improvements in animal productivity (i.e., liveweight gain milk production) and fertility (i.e., lower culling, lower replacement rates) can reduce GHG emissions/kg product. Additionally, intensification of production as output/ha can reduce emissions/kg product provided input requirements of feed and/or fertilizer are not excessive. Carbon sequestration into agricultural soils has the potential to offset emissions from pastoral based production systems. A product based metric is widely used and allows a wide range of objectives, including farm profitability and food security to be met. Variation in farm system parameters, and the inherent uncertainties associated with emission factors, can have substantial implications for reported agricultural emissions and thus, uncertainty or sensitivity analysis in any modelling approach is needed. Although there is considerable variation among studies in relation to quality of farm data, boundaries assumed, emission factors applied and co-product allocation approach, we suggest that whole farm systems models are an appropriate tool to develop and measure GHG mitigation strategies for livestock farms.This article is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.

Application Of Fuzzy Optimization In Diet Formulation

Feeding cost comprised about 65 to 75 percentage of dairy cattle production systems. Reduction feed cost and consideration seasonal or regional limitation of feed sources especially some forages increased necessity of the optimization of feed formulation in dairy caws. However, without a positive answer and accrue methods based on linear models those used on ration formulation, application of new mathematical models as fuzzy models seems to be very useful to taken account and meeting nutrient requirements and formulation based on ration least cost and composition in different levels. Fuzzy models promise to be a valuable tool as they link measurable information to linguistic interpretation using membership functions. The objective of this paper was using linear fuzzy model in formulation of dairy cow ration in early lactation and compare to linear programming models. Using linear programming models, the final cost of one kilogram of total mixed ration was 1333.5 Rails, and at this level cow nutrients requirements were met. Using fuzzy model and applying all restriction, the least cost for one kilogram of total mixed ration was 1222.5 Rails, and at this level cow nutrients requirements were met. Using fuzzy model in compare to linear programming models, feed cost was reduced about 8 percentages. The result of this experiment guarantees the formulation of ration using fuzzy models can be used to reduce feed cost and obtain different ration that they may met dairy cow nutrients requirements over different situations. In addition, because of the results in an illustrative example, it is concluded that the procedure outlined in this paper suitably deals with ration formulation and, therefore, enables a practical implementation of fuzzy evaluation of agricultural production systems.

The Use of Rose Bengal Plate Test to Asses Cattle Exposure to Brucella Infection in Traditional and Smallholder Dairy Production Systems of Tanga Region of Tanzania

A cross-sectional epidemiological study was conducted to determine the seroprevalence and to identify risk factors for bovine brucellosis seropositivity in traditional and smallholder dairy cattle production systems in the Tanga region of North-eastern Tanzania. The study populations comprised 246 indigenous and 409 crossbred cattle, randomly selected from 105 smallholder dairy and 25 traditional managed herds, respectively. Individual animal and herd-level data were collected using a structured questionnaire. Serum samples were screened for Brucella antibodies using the Rose Bengal Plate Test The overall seroprevalence of Brucella antibodies in the smallholder dairy and traditional managed cattle was 4.1% and 7.3% respectively. The corresponding overall herd prevalence was 10.5% and 20% respectively. Using multivariate logistic regression analysis, closeness to stock route, access to surface drinking water and location were identified as the major risk factors for individual herd seroprevalence. Older animals (≥6 years) were associated with increased risk of sero-positivity compared to animals of age category of ≤6 years. The results showed that brucellosis is prevalent and widely distributed locally, underscoring the need for further studies including surveillance and institution of preventive and control measures particularly among female young-stock and the general public who are at high risk of contracting brucellosis.

Development and Evaluation of a Simulation Model for Dairy Cattle Production Systems Integrated with Forage Crop Production

Crop-livestock mixed farming systems depend on the efficiency with which nutrients are conserved and recycled. Home-grown forage is used as animal feed and animal excretions are applied to cultivated crop lands as manure. The objective of this study was to develop a mixed farming system model for dairy cattle in Japan The model consisted of four sub-models: the nutrient requirement model, based on the Japanese Feeding Standards to determine requirements for energy, crude protein, dry matter intake, calcium, phosphorus and vitamin A; the optimum diet formulation model for determining the optimum diets that satisfy nutrient requirements at lowest cost, using linear programming; the herd dynamic model to calculate the numbers of cows in each reproductive cycle; and the whole farm optimization model to evaluate whole farm management from economic and environmental viewpoints and to optimize strategies for the target farm or system. To examine the model's validity, its predictions were compared against best practices for dairy farm management. Sensitivity analyses indicated that higher yielding cows lead to better economic results but higher emvironmental load in dairy cattle systems integrated with forage crop production.

Application of a Simulation Model for Dairy Cattle Production Systems Integrated with Forage Crop Production: the Effects of Whole Crop Rice Silage Utilization on Nutrient Balances and Profitability

In Japan, since rice consumption has been decreasing with the westernization of Japanese eating habits, surplus paddy fields have been increasing. If these surplus paddy fields can be utilized for forage rice production as feed for animal production and excretions (feces and urine) from animal production can be applied to the paddy fields as manure, then the problems of surplus paddy fields and excretions from animal production may be solved, and the environment kept sustainable. The objectives of the present study were to apply a bio-economic model to dairy and forage rice integration systems in Japan and to examine the merit of introducing whole crop rice silage (WCRS), as well as economic and environmental effects of various economic and management options in the systems. Five simulations were conducted using this model. The use of WCRS as a home-grown feed increased environmental loads and decreased economic benefit because of the higher amount of purchased feed, when compared to the use of typical crops such as maize, alfalfa and timothy silage (simulation 1). Higher economic benefits from higher forage rice yields and higher milk production of a dairy cow were obtained (simulations 2, 3). There were no economic and environmental incentives for utilizing crude protein (CP) rich WCRS, because an increase in the CP content in WCRS led to the use of more chemical fertilizers, resulting in high production costs and nitrogen outputs (simulation 4). When evaluated under the situation of a fixed herd size, increasing forage rice yields decreased the total benefit of the production, in spite of the fact that the amount of subsidies per unit of land increased (simulation 5). It was indicated that excess subsidy support may not promote yield of forage rice. It was, however, observed in most cases that dairy and forage rice integration systems could not be economically established without subsidies.

Productivity of Brachiaria humidicola pastures in the Atlantic forest region of Brazil as affected by stocking rate and the presence of a forage legume

Excessive intensification of dairy and beef cattle production systems in the industrialised countries has led to serious problems of pollution of water resources and the atmosphere. In order to develop an appropriate alternative, a few studies have been made by various research teams in Brazil, using low fertiliser inputs and modest animal stocking rates. The objective of this present study was to evaluate the effect of different stocking rates of beef cattle, and the introduction of a forage legume (Desmodium ovalifolium (Prain) Wall.), on the long-term sustainability of pastures of Brachiaria humidicola (Rendle) Schweick established in the Atlantic forest region of Brazil in the extreme south of the State of Bahia. Annual maintenance fertilisation was restricted to additions of 11 and 6 kg ha−1 of P and K, respectively (and no N). Live weight gain (LWG) of Zebu steers was evaluated for stocking rates of 2, 3 and 4 head ha−1 during six grazing periods from 1988 to 1997. Forage intake and the proportion of legume in the acquired ration was determined using steers fitted with oesophageal fistulae. The bolus samples were analysed manually in 1988–1989, and using the 13C natural abundance technique in 1995. There was no significant response of LWG to the presence of the legume in the acquired ration. LWG in the final grazing period (1995–1996) was similar to that recorded in 1988–1989 at all stocking rates, suggesting that this management regime resulted in long-term sustainable production even in the absence of the legume or of a N fertiliser input. This was confirmed by the soil fertility analyses for 1988 and 1997, where only levels of P showed a significant decrease. The net aerial primary productivity (NAPP) of the pasture was determined for 1995, the largest component being deposited litter (21–33 Mg DM ha−1 year−1), followed by forage intake (6.4–12.2 Mg DM ha−1 year−1).

First report of a 16SrXI group phytoplasma (Candidatus Phytoplasma oryzae) associated with Napier grass stunt disease in Uganda

Napier grass (Pennisetum purpureum), also known as elephant grass, is an important fodder crop in Uganda. The forage has been increasingly used in intensive (zero grazing) and semi-intensive dairy cattle production systems, in order to meet the increasing demand for milk in Uganda. Napier grass stunt disease, causing short internodes, bushy appearance, yellow to purple streaking and a low biomass yield, has spread among smallholder dairy farmers in Uganda since it was first observed in 2001 (Alacai et al., 2004). The disease has also been reported from western Kenya and shown to be associated with a phytoplasma (Jones et al., 2004) and in Tanzania (B. Pallangyo, personal communication). Leaf samples of stunted Napier grass were collected in the three major Napier grass-growing areas of Uganda. Air-dried leaf samples were ground in liquid nitrogen and total DNA was extracted using a DNeasy kit according to manufacturer's instructions (Qiagen). Leaves without symptoms were used as negative control. The presence of phytoplasma in plants with symptoms was confirmed by a real-time PCR method according to Christensen et al. (2004). Seven of these positive samples were sequenced in the 16S rRNA gene (deposited in GenBank Acc. No. EF012650) and the 16S/23S intergenic spacer (Acc. No. EF012649). No sequence variation was found. The sequences were 99·3% identical to the 16S rRNA sequences from the phytoplasma associated with Napier grass stunt from Kenya, which belongs to the 16SrXI rice yellow dwarf group (Candidatus Phytoplasma oryzae; Jones et al., 2004). This is the first report of a 16SrXI Group phytoplasma associated with Napier grass stunt disease in Uganda.

A stochastic model for the derivation of economic values and their standard deviations for production and functional traits in dairy cattle

The objective of this paper was to present a model of a dairy cattle production system for the derivation of economic values and their standard deviations for both production and functional traits under Danish production circumstances. The stochastic model used is dynamic, and simulates production and health in a dairy herd. Because of indirect effects between traits, the phenotypic levels of (related) traits can change as a result of genetic changes. Economic values for milk production and body weight were 0.28 and −0.76 €/kg per cow-year respectively. For incidence of milk fever, mastitis, retained placenta and laminitis economic values were −402.1, −162.5, −79.0 and −210.2 €/incidence per cow-year. The economic values for involuntary culling rate, stillbirth and conception rate were –6.66, −1.63, and 1.98 €/% per cow-year, respectively and the economic value for days from calving to first heat was −0.94 €/day per cow-year. Standard deviations of economic values expressing variation in realised profit of a farm before and after a genetic change were computed using a linear Taylor series expansion. Expressed as coefficient of variation, standard deviations of economic values based on 1000 replicates ranged between 0.07 (milk production) to 16 (retained placenta).

Water quality of the Canchim’s creek watershed in São Carlos, SP, Brazil, occupied by beef and dairy cattle activities

The Canchim’s creek watershed in São Carlos, SP, Brazil, was chosen to evaluate water quality affected by dairy and beef cattle production systems based on tropical pasture. The water samples were collected monthly, during three years, at six sampling points: spring in a tropical forest, spring in an intensive dairy production system, two dam springs, and stream water upward and at the delta. Results showed differences (P<0.01) among sampling points for the mean parameters. True color, hardness, turbidity, electric conductivity, alkalinity, pH, chemical oxygen demand and consumed oxygen explained well differences among sampling points. According to current legislation standards, water quality fitted with most of the established parameters for class 2, with exception of phosphate and iron. The high levels of total phosphorus, except in the forest spring, classified this water in an eutrophic class, even where soil and water conservation practices were considered adequate.

Neutron activation analysis of zinc in forages used in intensive dairy cattle production systems

Instrumental neutron activation analysis (INAA) was applied for the determination of Zn concentration in the main tropical grass forages used in intensive dairy cattle production systems, in Brazil. Smaller Zn concentration could be verified in the rainy period. Comparison of results obtained in these analyses of forages dry matter with daily requirements pointed towards deficiency of Zn in the forages.

Cow milk and human development and well-being

Fifty years ago animal foods were considered complete foods and important for human health. In most developed countries substantial dairy cattle and milk production industries existed which made major contributions to human welfare including the provision of cow milk to infants and young children. Then, over the last forty years, hypotheses have been developed largely by the medical profession and associated fields of research on the unfavourable roles of dietary cholesterol (DC), animal fats and serum cholesterol (SC) in coronary heart diseases (CHD). These postulates resulted in new and strange equalities such as DC+animal fat=SC=CHD. These hypotheses were followed by simplistic dietary recommendations with warnings against animal fats. These warnings have been heeded by the medical profession in many developed countries and under medical authority large sections of the public have made dietary changes and the per capita consumption of milk has fallen. More recently other risk factors have been found for CHD, and knowledge of their relative importance has increased. Understanding has grown over the question of versatility, optima and interactions between nutrients. Other new factors in this field include: the minor effect of DC on SC, the U-shaped effect of SC on total mortality in men with no effect in women less than 50 years of age, positive effects of other milk constituents on SC, different effects of high density C (HDL-C) and low density C (LDL-C) and of saturated, monounsaturated and polyunsaturated fatty acids (SFA, MUFA, PUFA) on CHD risk, the harmful effects of trans-FA, the meaninglessness of the P/S ratio, the medical and non-medical side effects of lowering SC and the high heritability of SC. These new recoveries have not been given the publicity accorded to the original hypotheses. It is the aim of this paper to seek a balanced review of the subject in the light of new scientific evidence. Further the broader implications of the topic for society, human development and well-being are also considered. Thus there are two main theses in this paper. One is to review the hypotheses of the relationship between cow milk and human coronary heart disease. These hypotheses are examined and their original historic deficiencies are discussed. This is followed by the new and emerging scientific evidence to support, question or refute these original hypotheses. The second major thesis in this paper deals with the impact which these hypotheses have had upon the pattern of human nutrition which are reflected in many important economic, social and other nutritional issues, all of which merit attention. It is considered inadequate to base general recommendations in the field of human health and well-being solely or mainly upon postulations about the relationship between milk and CHD without taking into account the larger and more complex issues. In addition to the general field of human health, the consequences of these hypotheses include the responses of the dairy production and processing industries. For example, if the hypotheses are reliable, tested and to become basic components of human nutrition, then the milk production industry has to reshape its system to produce a product more suited to the changes in consumption. If however, the assumptions are not substantiated permanently the such a re-tooling of milk production is futile. Milk production represents a major component in global food production and the implications of change are enormous. Issues to be considered include the efficiency of dairy cow in converting plant material, inedible to humans, to a human food of high nutritional value, the economic and nutritional contribution of dairy cattle production systems to beef production, the strong genetic correlations between the fat content, the protein content and the yield of milk per cow, the slowness of achieving changes in milk composition in bovine species with low reproductive rates and long generation intervals, and interactions between nutrients. Further, there are other broader issues including the incidence of other human conditions and diseases besides CHD, which can be affected by the presence or absence of milk in the diet, the genetic differences between individuals and human races, the need to address the hunger of the world's human population and further economic, social and psychological factors. Many questions need research to find sustainable breeding goals and milk production systems which are related to the reality of how milk contributes to human development and welfare. The paper concludes by considering the negative impact which the questionable hypotheses have had upon an important component of food production, namely dairy cattle farming which historically has contributed enormously to human development and welfare. The author considers there is a vacuum of knowledge here which cannot be filled simply by expertise in the medical field alone. The issue is a prime candidate for interdisciplinary research.