17 results
The characterization of the cow-calf, stocker and feedlot cattle industry water footprint to assess the impact of livestock water use sustainability
- H. M. Menendez III, L. O. Tedeschi
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- The Journal of Agricultural Science / Volume 158 / Issue 5 / July 2020
- Published online by Cambridge University Press:
- 24 August 2020, pp. 416-430
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Perception of freshwater use varies between nations and has led to concerns of how to evaluate water use for sustainable food production. The water footprint of beef cattle (WFB) is an important metric to determine current levels of freshwater use and to set sustainability goals. However, current WFB publications provide broad WF values with inconsistent units preventing direct comparison of WFB models. The water footprint assessment (WFA) methodologies use static physio-enviro-managerial equations, rather than dynamic, which limits their ability to estimate cattle water use. This study aimed to advance current WFA methods for WFB estimation by formulating the WFA into a system dynamics methodology to adequately characterize the major phases of the beef cattle industry and provide a tool to identify high-leverage solutions for complex water use systems. Texas is one of the largest cattle producing areas in the United States, a significant water user. This geolocation is an ideal template for WFB estimation in other regions due to its diverse geography, management-cultures, climate and natural resources. The Texas Beef Water Footprint model comprised seven submodels (cattle population, growth, nutrition, forage, WFB, supply chain and regional water use; 1432 state variables). Calibration of our model replicated initial WFB values from an independent study by Chapagain and Hoekstra in 2003 (CH2003). This CH2003 v. Texas production scenarios evaluated model parameters and assumptions and estimated a 41–66% WFB variability. The current model provides an insightful tool to improve complex, unsustainable and inefficient water use systems.
An improved algorithm for solving profit-maximizing cattle diet problems
- J. G. O. Marques, R. de O. Silva, L. G. Barioni, J. A. J. Hall, L. O. Tedeschi, D. Moran
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Feeding cattle with on-pasture supplementation or feedlot diets can increase animal efficiency and system profitability while minimizing environmental impacts. However, cattle system profit margins are relatively small and nutrient supply accounts for most of the costs. This paper introduces a nonlinear profit-maximizing diet formulation problem for beef cattle based on well-established predictive equations. Nonlinearity in predictive equations for nutrient requirements poses methodological challenges in the application of optimization techniques. In contrast to other widely used diet formulation methods, we develop a mathematical model that guarantees an exact solution for maximum profit diet formulations. Our method can efficiently solve an often-impractical nonlinear problem by solving a finite number of linear problems, that is, linear time complexity is achieved through parametric linear programming. Results show the impacts of choosing different objective functions (minimizing cost, maximizing profit and maximizing profit per daily weight gain) and how this may lead to different optimal solutions. In targeting improved ration formulation on feedlot systems, this paper demonstrates how profitability and nutritional constraints can be met as an important part of a sustainable intensification production strategy.
A multi-inverse approach for a holistic understanding of applied animal science systems
- L. M. Vargas-Villamil, L. O. Tedeschi, S. Medina-Peralta, F. Izquierdo-Reyes, J. Navarro-Alberto, R. González-Garduño
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Technological and mathematical advances have provided opportunities to investigate new approaches for the holistic quantification of complex biological systems. One objective of these approaches, including the multi-inverse deterministic approach proposed in this paper, is to deepen the understanding of biological systems through the structural development of a useful, best-fitted inverse mechanistic model. The objective of the present work was to evaluate the capacity of a deterministic approach, that is, the multi-inverse approach (MIA), to yield meaningful quantitative nutritional information. To this end, a case study addressing the effect of diet composition on sheep weight was performed using data from a previous experiment on saccharina (a sugarcane byproduct), and an inverse deterministic model (named Paracoa) was developed. The MIA successfully revealed an increase in the final weight of sheep with an increase in the percentage of corn in the diet. Although the soluble fraction also increased with increasing corn percentage, the effective nonsoluble degradation increased fourfold, indicating that the increased weight gain resulted from the nonsoluble substrate. A profile likelihood analysis showed that the potential best-fitted model had identifiable parameters, and that the parameter relationships were affected by the type of data, number of parameters and model structure. It is necessary to apply the MIA to larger and/or more complex datasets to obtain a clearer understanding of its potential.
PW01-237 - Low-Dosage Topiramate In Alcohol Dependence: A Randomized, Double-Blind, Placebo-Controlled Trial
- G. Martinotti, M. Di Nicola, O. De Vita, D. Tedeschi, L. Guerriero, R. Guglielmo, R. De Filippis, L. Janiri
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- Journal:
- European Psychiatry / Volume 25 / Issue S1 / 2010
- Published online by Cambridge University Press:
- 17 April 2020, 25-E1644
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Introduction
Topiramate (up to 300 mg per day) is more efficacious than placebo as an adjunct to standardised medication compliance management in treatment of alcohol dependence. However, adverse events can limit its use in different clinical situation. In this randomised, double-blind, placebo controlled trial we aimed to investigate the efficacy of low-dosage topiramate on alcohol drinking indices. Craving and psychiatric symptoms improvements were the secondary endpoints.
MethodsForty alcohol dependent subjects where detoxified and subsequently randomised into two groups, respectively receiving topiramate (100mg/die) or Placebo. The level of craving for alcohol was evaluated by a 10-cm Visual Analogue Scale (VAS) and the Italian -version of the Obsessive and Compulsive Drinking Scale (OCDS). Psychiatric symptomatology was evaluated by the Symptom Check List 90 Revised (SCL-90 R).
ResultsThe improvement of alcohol drinking indices and craving scores was higher in the topiramate group than placebo. The survival function showed that patients treated with topiramate remained abstinent from any alcohol amount for a longer time with respect to placebo (Z= -2.197; P< 0.05). The SCL-90-R general index of “Positive Symptom Total” significantly reduced in the topiramate group (F= 3.41, p< 0.05). The number of patients dropped-out from the study for adverse events was not different between groups.
DiscussionTo our knowledge, this is the first randomised, parallel group trial to evaluate the efficacy of topiramate at low dosage for alcohol dependence. The use of topiramate at low dosage could increase the number of subjects in treatment, given the reduced possibility of adverse events.
Oxcarbazepine vs. Topiramate in Alcohol Dependence
- G. Martinotti, M. Di Nicola, D. Tedeschi, O. De Vita, L. Guerriero, R. Guglielmo, M. Mazza, G. Pozzi, L. Janiri
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- Journal:
- European Psychiatry / Volume 24 / Issue S1 / January 2009
- Published online by Cambridge University Press:
- 16 April 2020, 24-E411
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Introduction:
Aim of this randomised, parallel, placebo-controlled group trial was to compare oxcarbazepina and topiramate with placebo on alcohol drinking indices. Craving and psychiatric simptomatology have also been investigated.
Methods:This randomised, parallel, placebo-controlled psychopharmacology trial studied 60 patients, consecutively recruited, meeting clinical criteria for Alcohol Dependence (DSM-IV). After detoxification, subjects were assigned to flexible doses of oxcarbazepine (n=20), or topiramate (n=20) or placebo (n=20). Withdrawal symptomatology was determined by the Clinical Institute Withdrawal Assessment for Alcohol (CIWA-Ar) and the level of craving for alcohol was evaluated by a 10-cm Visual Analogue Scale (VAS) and the Italian -version of the Obsessive and Compulsive Drinking Scale (OCDS). Psychiatric symptoms were evaluated with the Symptom Check List 90 Revised (SCL-90 R).
Results:Non-benzodiazepine anticonvulsants have been shown to be efficacious treatments for the prevention of alcohol relapse although the FDA has yet approved none of these agents. During the congress the main results of this study will be presented.
Conclusions:To our knowledge, this is the first randomised, parallel, placebo-controlled group study to evaluate the efficacy of oxcarbazepine and topiramate compared in alcohol dependent patients. The data of this pilot clinical study suggest and investigate a possible role for the anticonvulsants agents in the treatment of alcohol dependent patients.
1896 – Executive Functions And Impulsivity In Alcohol Dependence: Focus On Drinking Behaviour
- D. Tedeschi, G. Martinotti, M. Di Nicola, O. De Vita, D.S. Hatzigiakoumis, G. Pozzi, L. Janiri
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- European Psychiatry / Volume 28 / Issue S1 / 2013
- Published online by Cambridge University Press:
- 15 April 2020, 28-E1136
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There is increasing consensus on the notion of addiction as a brain disorder characterized by longstanding changes in cognitive functioning, especially in so-called executive functions. Recent evidences indicate that specific components of executive functions, considered the domain of the frontal lobes, including dysfunctional impulsivity, could be considered a hallmark of addiction.
Aim of the present study was to explore the domain of executive functions in abstinent non comorbid alcohol dependent subjects, in comparison with matched non clinical controls. Any relationship with impulsivity and drinking behaviour (binge drinking) was also investigated.
We used a selective battery of neuropsychological tests designed to assess several components of executive functions, including fluency, working memory, analogical reasoning, interference and cognitive flexibility, attention, concentration, problem solving strategy and abstract reasoning. BIS-11 was also administered to explore impulsivity levels.
Significant differences in many of the domains explored between alcohol dependent patients and controls have been founded. Intriguingly, impulsivity in alcoholics seems to not inhibit cognitive performance. Data about binge drinking will be also presented.
Our results show that alcohol dependent patients present a weaker performance in all the domains referable to executive functions when compared to controls. Disruptions in inhibitory control are central to many theories of addiction; the inhibitory activities of the Frontal and Prefrontal Cortex, are particularly important when an individual needs to over-ride a reflexive response, such as a craving response to drug-related cues.
P-95 - Executive Functions, Anger and Impulsivity in Alcohol Dependence
- D. Tedeschi, G. Martinotti, M. Di Nicola, O. De Vita, G. Pozzi, L. Janiri
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- Journal:
- European Psychiatry / Volume 27 / Issue S1 / 2012
- Published online by Cambridge University Press:
- 15 April 2020, p. 1
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There is increasing consensus on the notion of addiction as a brain disorder characterized by longstanding changes in cognitive functioning, especially in so-called executive functions. Recent evidences indicate that specific components of executive functions, considered the domain of the frontal lobes, including dysfunctional impulsivity, could be considered a hallmark of addiction. Aim of the present study was to explore the domain of executive functions in abstinent non comorbid alcohol dependent subjects in comparison with matched non clinical controls. Any relationship with impulsivity and anger was also investigated.
Thirty Alcohol Dependent outpatients with diagnosis of Alcohol Dependence (DSM-IV-TR) and thirty matched control subjects participated to the study. We used a selective battery of neuropsychological tests designed to assess several components of executive functions, including fluency, working memory, analogical reasoning, interference and cognitive flexibility, attention, concentration, problem solving strategy and abstract reasoning (FAS for verbal fluency; Semantic Fluency; Digit span; Spatial span; Similarities; Stroop test; Wisconsin Card Sorting Test; TMT Making Test Parts A & B; Digit Symbol). BIS-11 and STAXI I and II were also administered to explore impulsivity and anger levels.
Significant differences in many of the domains explored between alcohol dependent patients and controls have been founded. Furthermore, a correlation between the performance at neuropsychological tests and the score at the instruments designed to assess impulsivity and anger have been deducted.
Alcohol dependence is associated with a significant impairment on executive domain. Impulsivity and anger levels, both dimensions linked with the executive capacity, seem to be altered as well.
O-36 - Topiramate at low Dosage Vs. Placebo in Alcohol Dependence
- O. De Vita, G. Martinotti, M. Di Nicola, D. Tedeschi, D.S. Hatzigiakoumis, M. Monetta, G. Pozzi, L. Janiri
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- Journal:
- European Psychiatry / Volume 27 / Issue S1 / 2012
- Published online by Cambridge University Press:
- 15 April 2020, p. 1
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Non-benzodiazepine anticonvulsant agents have been shown to be efficacious treatments for the prevention of alcohol relapse although the FDA has yet approved none of these agents. Several studies have demonstrated topiramate's efficacy in improving drinking behavior and maintaining abstinence. The objective of the present randomised, parallel, placebo-controlled trial was to compare topiramate at low dosage with placebo on alcohol drinking indices and craving in detoxified alcohol dependent subjects. Psychiatric symptomatology, quality of life and clinical global improvement have also been investigated.
Sixty detoxified Alcohol Dependent (DSM-IV-TR) outpatients were recruited and randomly assigned to receive topiramate low dosage (n = 30) or placebo (n = 30). Patients have been evaluated after 30, 90 and 180 days of treatment.
Withdrawal symptomatology was determined by the Clinical Institute Withdrawal Assessment for Alcohol (CIWA-Ar); craving for alcohol was evaluated by a 10-cm Visual Analogue Scale (VASc) and the Obsessive and Compulsive Drinking Scale (OCDS). Psychiatric symptoms were evaluated with the Symptom Check List 90-Revised (SCL-90-R), quality of life with the QL-INDEX; the Clinical Global Impression (CGI) was also administered.
As to our results, topiramate is more efficacy than placebo on both the improvement of withdrawal symptomatology and the reduction of relapses. Furthermore, it has resulted effective in reducing craving, the severity of global psychopathology and the quality of life.
The data of this pilot study investigate and suggest a possible role for the anticonvulsants agents in the treatment of alcohol dependence. Topiramate could be an alternative option beyond the already approved agents for the treatment of alcohol dependence.
The balance of adult mental health care: provision of core health versus other types of care in eight European countries
- G. Cetrano, L. Salvador-Carulla, F. Tedeschi, L. Rabbi, M. R. Gutiérrez-Colosía, J. L. Gonzalez-Caballero, A.-L. Park, D. McDaid, R. Sfetcu, J. Kalseth, B. Kalseth, Ø. Hope, M. Brunn, K. Chevreul, C. Straßmayr, G. Hagmair, K. Wahlbeck, F. Amaddeo, for the REFINEMENT group
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- Journal:
- Epidemiology and Psychiatric Sciences / Volume 29 / 2020
- Published online by Cambridge University Press:
- 17 October 2018, e6
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Aims
Although many mental health care systems provide care interventions that are not related to direct health care, little is known about the interfaces between the latter and core health care. ‘Core health care’ refers to services whose explicit aim is direct clinical treatment which is usually provided by health professionals, i.e., physicians, nurses, psychologists. ‘Other care’ is typically provided by other staff and includes accommodation, training, promotion of independence, employment support and social skills. In such a definition, ‘other care’ does not necessarily mean being funded or governed differently. The aims of the study were: (1) using a standard classification system (Description and Evaluation of Services and Directories in Europe for Long Term Care, DESDE-LTC) to identify ‘core health’ and ‘other care’ services provided to adults with mental health problems; and (2) to investigate the balance of care by analysing the types and characteristics of core health and other care services.
MethodsThe study was conducted in eight selected local areas in eight European countries with different mental health systems. All publicly funded mental health services, regardless of the funding agency, for people over 18 years old were identified and coded. The availability, capacity and the workforce of the local mental health services were described using their functional main activity or ‘Main Types of Care’ (MTC) as the standard for international comparison, following the DESDE-LTC system.
ResultsIn these European study areas, 822 MTCs were identified as providing core health care and 448 provided other types of care. Even though one-third of mental health services in the selected study areas provided interventions that were coded as ‘other care’, significant variation was found in the typology and characteristics of these services across the eight study areas.
ConclusionsThe functional distinction between core health and other care overcomes the traditional division between ‘health’ and ‘social’ sectors based on governance and funding. The overall balance between core health and other care services varied significantly across the European sites. Mental health systems cannot be understood or planned without taking into account the availability and capacity of all services specifically available for this target population, including those outside the health sector.
Review: Precision nutrition of ruminants: approaches, challenges and potential gains
- L. A. González, I. Kyriazakis, L. O. Tedeschi
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A plethora of sensors and information technologies with applications to the precision nutrition of herbivores have been developed and continue to be developed. The nutritional processes start outside of the animal body with the available feed (quantity and quality) and continue inside it once the feed is consumed, degraded in the gastrointestinal tract and metabolised by organs and tissues. Finally, some nutrients are wasted via urination, defecation and gaseous emissions through breathing and belching whereas remaining nutrients ensure maintenance and production. Nowadays, several processes can be monitored in real-time using new technologies, but although these provide valuable data ‘as is’, further gains could be obtained using this information as inputs to nutrition simulation models to predict unmeasurable variables in real-time and to forecast outcomes of interest. Data provided by sensors can create synergies with simulation models and this approach has the potential to expand current applications. In addition, data provided by sensors could be used with advanced analytical techniques such as data fusion, optimisation techniques and machine learning to improve their value for applications in precision animal nutrition. The present paper reviews technologies that can monitor different nutritional processes relevant to animal production, profitability, environmental management and welfare. We discussed the model-data fusion approach in which data provided by sensor technologies can be used as input of nutrition simulation models in near-real time to produce more accurate, certain and timely predictions. We also discuss some examples that have taken this model-data fusion approach to complement the capabilities of both models and sensor data, and provided examples such as predicting feed intake and methane emissions. Challenges with automatising the nutritional management of individual animals include monitoring and predicting of the flow of nutrients including nutrient intake, quantity and composition of body growth and milk production, gestation, maintenance and physical activities at the individual animal level. We concluded that the livestock industries are already seeing benefits from the development of sensor and information technologies, and this benefit is expected to grow exponentially soon with the integration of nutrition simulation models and techniques for big data analysis. However, this approach may need re-evaluating or performing new empirical research in both fields of animal nutrition and simulation modelling to accommodate a new type of data provided by the sensor technologies.
Development of equations, based on milk intake, to predict starter feed intake of preweaned dairy calves
- A. L. Silva, T. J. DeVries, L. O. Tedeschi, M. I. Marcondes
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There is a lack of studies that provide models or equations capable of predicting starter feed intake (SFI) for milk-fed dairy calves. Therefore, a multi-study analysis was conducted to identify variables that influence SFI, and to develop equations to predict SFI in milk-fed dairy calves up to 64 days of age. The database was composed of individual data of 176 calves from eight experiments, totaling 6426 daily observations of intake. The information collected from the studies were: birth BW (kg), SFI (kg/day), fluid milk or milk replacer intake (MI; l/day), sex (male or female), breed (Holstein or Holstein×Gyr crossbred) and age (days). Correlations between SFI and the quantitative variables MI, birth BW, metabolic birth BW, fat intake, CP intake, metabolizable energy intake, and age were calculated. Subsequently, data were graphed, and based on a visual appraisal of the pattern of the data, an exponential function was chosen. Data were evaluated using a meta-analysis approach to estimate fixed and random effects of the experiments using nonlinear mixed coefficient statistical models. A negative correlation between SFI and MI was observed (r=−0.39), but age was positively correlated with SFI (r=0.66). No effect of liquid feed source (milk or milk replacer) was observed in developing the equation. Two equations, significantly different for all parameters, were fit to predict SFI for calves that consume less than 5 (SFI<5) or more than 5 (SFI>5) l/day of milk or milk replacer: ${\rm SFI}_{{\,\lt\,5}} {\equals}0.1839_{{\,\pm\,0.0581}} {\times}{\rm MI}{\times}{\rm exp}^{{\left( {\left( {0.0333_{{\,\pm\,0.0021 }} {\minus}0.0040_{{\,\pm\,0.0011}} {\times}{\rm MI}} \right){\times}\left( {{\rm A}{\minus}{\rm }\left( {0.8302_{{\,\pm\,0.5092}} {\plus}6.0332_{{\,\pm\,0.3583}} {\times}{\rm MI}} \right)} \right)} \right)}} {\minus}\left( {0.12{\times}{\rm MI}} \right)$ ; ${\rm SFI}_{{\,\gt\,5}} {\equals}0.1225_{{\,\pm\,0.0005 }} {\times}{\rm MI}{\times}{\rm exp}^{{\left( {\left( {0.0217_{{\,\pm\,0.0006 }} {\minus}0.0015_{{\,\pm\,0.0001}} {\times}{\rm MI}} \right){\times}\left( {{\rm A}{\minus}\left( {3.5382_{{\,\pm\,1.3140 }} {\plus}1.9508_{{\,\pm\,0.1710}} {\times}{\rm MI}} \right)} \right)} \right)}} {\minus}\left( {0.12{\times}{\rm MI}} \right)$ where MI is the milk or milk replacer intake (l/day) and A the age (days). Cross-validation and bootstrap analyses demonstrated that these equations had high accuracy and moderate precision. In conclusion, the use of milk or milk replacer as liquid feed did not affect SFI, or development of SFI over time, which increased exponentially with calf age. Because SFI of calves receiving more than 5 l/day of milk/milk replacer had a different pattern over time than those receiving <5 l/day, separate prediction equations are recommended.
Predicting the amount of urea nitrogen recycled and used for anabolism in growing cattle
- J. H. EISEMANN, L. O. TEDESCHI
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- The Journal of Agricultural Science / Volume 154 / Issue 6 / August 2016
- Published online by Cambridge University Press:
- 31 March 2016, pp. 1118-1129
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In ruminants, urea nitrogen (N) produced by the liver and recycled to the gastrointestinal tract (GIT) provides a source of N for microbial growth and also conserves N. In this respect, it buffers the dietary supply of N available for microbial growth and microbial protein supply. The equation for recycled N in the National Research Council's (NRC 1996, 2000) beef model is based on relationships between ruminal ammonia and plasma urea N concentrations. The objective of the current paper was to estimate recycled N available for anabolism (i.e., urea N used for anabolism, UUA) using available kinetic data. A meta-analysis was conducted using results reported in nine publications that measured urea N kinetics using the dual-labelled urea technique in growing cattle. Diets used in these experiments were predominantly forage-based. Urea production was linearly related to N intake (NI, g/day). Growing cattle converted 74·5% of the incremental NI to urea N. As NI increased, a smaller proportion of the urea produced was recycled to the GIT. On average, 54·4% of the urea N recycled to the GIT was used for anabolism; however, this percentage was not constant. As NI or dietary crude protein (CP) increased (g/kg dry matter, DM), proportionately less of the urea produced was used for anabolism. Nonlinear equations were developed to predict UUA based on NI or dietary CP in the current database and simulated at 5 or 10 kg of daily DM intake (DMI) over the same range of NI (g/day) and therefore, for diets differing in CP content (g/kg DM). The equation based on NI had a quadratic behaviour and the same estimated UUA for both levels of DMI. The equation based on CP showed a relatively small increase in UUA at low DMI and increased UUA at the higher DMI as NI increased. For both equations and both DMI, the pattern suggested a limit to use of recycled N for anabolism.
Developing a conceptual model of possible benefits of condensed tannins for ruminant production
- L. O. Tedeschi, C. A. Ramírez-Restrepo, J. P. Muir
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Enteric methane (CH4) emissions from ruminants have compelled a wide range of research initiatives to identify environmental abatement opportunities. However, although such mitigations can theoretically be attained with feed additives and feeding strategies, the limited empirical evidence on plant extracts used as feed additives does not support extensive or long-term reductions. Nevertheless, their strategic use (i.e. alone or combined in a simultaneous or consecutive use) may provide not only acceptable CH4 abatement levels, but also relevant effects on animal physiology and productivity. Condensed tannins (CT) represent a range of polyphenolic compounds of flavan-3-ol units present in some forage species that can also be added to prepared diets. Methods to determine CT, or their conjugated metabolites, are not simple. Although there are limitations and uncertainties about the methods to be applied, CT are thought to reduce CH4 production (1) indirectly by binding to the dietary fibre and/or reducing the rumen digestion and digestibility of the fibre and (2) directly by inhibiting the growth of rumen methanogens. On the basis of their role in livestock nutrition, CT influence the digestion of protein in the rumen because of their affinity for proteins (e.g. oxidative coupling and H bonding at neutral pH) that causes the CT-protein complex to be insoluble in the rumen; and dissociate in the abomasum at pH 2.5 to 3.0 for proteolysis and absorption in the small intestine. CT may also reduce gastro-intestinal parasite burdens and improve reproductive performance, foetal development, immune system response, hormone serum concentrations, wool production and lactation. The objectives of this paper are to discuss some of the beneficial and detrimental effects of CT on ruminant production systems and to develop a conceptual model to illustrate these metabolic relationships in terms of systemic physiology using earlier investigations with the CT-containing legume Lotus corniculatus. Our conceptual model indicated four complex and long-lasting relationships (digestive, toxicological, physiological and morphological) that can alter the normal biology of the animal. These relationships are interdependent, integrative, and sometimes, complementary to each other. This conceptual model can be used to develop mechanistic models to improve the understanding of the interaction between CT and the ruminants as well as to guide research initiatives of the impact of polyphenol-rich foods on human health.
Comparison of growth curves of two genotypes of dairy goats using nonlinear mixed models
- J. G. L. REGADAS FILHO, L. O. TEDESCHI, M. T. RODRIGUES, L. F. BRITO, T. S. OLIVEIRA
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- The Journal of Agricultural Science / Volume 152 / Issue 5 / October 2014
- Published online by Cambridge University Press:
- 27 November 2013, pp. 829-842
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The objective of the current study was to assess the use of nonlinear mixed model methodology to fit the growth curves (weight v. time) of two dairy goat genotypes (Alpine, +A and Saanen, +S). The nonlinear functions evaluated included Brody, Von Bertalanffy, Richards, Logistic and Gompertz. The growth curve adjustment was performed using two steps. First, random effects u1, u2 and u3 were linked to the asymptotic body weight (β1), constant of integration (β2) and rate constant of growth (β3) parameters, respectively. In addition to a traditional fixed-effects model, four combinations of models were evaluated using random variables: all parameters associated with random effects (u1, u2 and u3), only β1 and β2 (u1 and u2), only β1 and β3 (u1 and u3) and only β1 (u1). Second, the fit of the best adjusted model was refined by using the power variance and modelling the error structure. Residual variance ($\sigma _e^2 $) and the Akaike information criterion were used to evaluate the models. After the best fitting model was chosen, the genotype curve parameters were compared. The residual variance was reduced in all scenarios for which random effects were considered. The Richards (u1 and u3) function had the best fit to the data. This model was reparameterized using two isotropic error structures for unequally spaced data, and the structure known in the literature as SP(MATERN) proved to be a better fit. The growth curve parameters differed between the two genotypes, with the exception of the constant that determines the proportion of the final size at which the inflection point occurs (β4). The nonlinear mixed model methodology is an efficient tool for evaluating growth curve features, and it is advisable to assign biologically significant parameters with random effects. Moreover, evaluating error structure modelling is recommended to account for possible correlated errors that may be present even when using random effects. Different Richard growth curve parameters should be used for the predominantly Alpine and Saanen genotypes because there are differences in their growth patterns.
Evaluating the statistical variation in estimating forage dry matter intake of grazing Brahman bulls using n-alkanes
- A. DE-STEFANI AGUIAR, T. D. A. FORBES, F. M. ROUQUETTE, JR., L. O. TEDESCHI, R. D. RANDEL
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- The Journal of Agricultural Science / Volume 151 / Issue 1 / February 2013
- Published online by Cambridge University Press:
- 12 April 2012, pp. 129-140
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The objectives of the current study were to determine the variation structure within a day and across days when determining dry matter intake (DMI) of Coastal bermudagrass (Cynodon dactylon (L.) Pers.) pasture using dotriacontane (C32) as an external marker, to determine the optimal times for faecal collection for forage DMI estimation and to compare C31 and C33 as internal markers in estimating forage DMI in Brahman bulls. Sixteen Brahman bulls were allocated by weight to four pastures, and stocked at a moderate to low grazing pressure for 63 days from late June to the end of August. Three intake measurement periods (P1, P2, P3) were used; each period consisting of 10 days of twice daily C32 (400 mg/day) administration. Faecal collections were taken during the last 5 days (07.00, 11.00, 15.00 and 19.00 h). The C32 was individually hand fed using Calan gates, with maize gluten as a carrier for the alkane. Gas chromatography was used to determine n-alkanes in the forage and faecal samples. The concentration of C31 was less than C33 in the bermudagrass for all periods (P < 0·001), but the concentration of C31 and C33 in faeces was not significantly different (P > 0·05). The average concentration of C32 in the forage was 5·1, 7·6 and 9·6 mg/kg dry matter (DM), for P1, P2 and P3, respectively, with an average of 7·5 mg/kg DM for all periods. During P1 and P2, the estimation of forage DMI using C33 had a better fit (smaller –2 × log and Akaike's information criterion (AIC)) than using C31 either with or without adjustments for C32. The variation in estimated forage DMI decreased when forage C32 was not included. The variances of forage DMI were similar using C31 across days, but the Pearson correlations between days were low, which suggested that several days of collection were needed to estimate forage DMI accurately. Correlations between collection times within days were medium to high for all periods and varied from 0·65 to 0.97 for C31 and from 0·26 to 0·96 for C33. When all periods were analysed together, estimates of forage DMI either using C31 or C33 had low correlations between days of collection. Adjustment for C32 did not improve the variance and (co)variance matrix. In summary, C33/C32 had the lowest variation in estimating forage DMI, and at least 5 days of faecal collection were needed to decrease the variability of estimating forage DMI. The optimum times for faecal collection were 07.00 and 19.00 h, and it was important to adjust for C32 alkane concentration in estimating forage DMI in Brahman bulls grazing Coastal bermudagrass.
Development and evaluation of empirical equations to predict ruminal fractional passage rate of forages in goats
- L. O. TEDESCHI, A. CANNAS, S. G. SOLAIMAN, R. A. M. VIEIRA, N. K. GURUNG
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- The Journal of Agricultural Science / Volume 150 / Issue 1 / February 2012
- Published online by Cambridge University Press:
- 20 July 2011, pp. 95-107
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The objectives of the present paper were to develop and evaluate empirical equations to predict fractional passage rate (kp) of forages commonly fed to goats using chemical composition of the diet and animal information. Two databases were created. The first (development database) was assembled from four studies that had individual information on animals, diets and faecal marker concentrations over time (up to 120 h post-feeding); it contained 54 data points obtained from Latin square designs. The second (evaluation database) was built using published information gathered from the literature. The evaluation database was comprised of five studies, containing 39 data points on diverse types of diets and animal breeds. The kp was estimated using a time-dependent model based on the Gamma distribution with at least two and up to 12 (rumen)+one (post-rumen) compartments (i.e. G2G1–G12G1) developed from the development database. Statistical analyses were carried out using standard regression analysis and random coefficient model analysis to account for random sources (i.e. study). The evaluation of the developed empirical equation was conducted using regression analysis adjusted for study effects, concordance correlation coefficient and mean square error of prediction. Sensitivity analyses with the developed empirical equation and comparable published equations were performed using Monte Carlo simulations. The G2G1 model consistently had lower sum of squares of errors and greater relative likelihood probabilities than other GnG1 versions. The kp was influenced by several dietary nutrients, including dietary concentration or intake of components such as lignin, neutral detergent fibre (NDF), hemicellulose, crude protein (CP), acid detergent fibre (ADF) and animal body weight (BW). The selected empirical equation, adjusted for study effects, () had an R2 of 0·623 and root of mean square error (RMSE) of 0·0122/h. The evaluation of the adequacy of the selected equation with the evaluation database indicated no systematic bias (slope not different from 1), but a low accuracy (0·33) and a persistent mean bias of 0·0129/h. The sensitivity analysis indicated that the selected empirical equation was most sensitive to changes in dry matter intake (DMI, kg/d), BW(kg) and NDF (g/kg dry matter) with standardized regression coefficients of 0·98, −0·43 and −0·32, respectively. The sensitivity analysis also indicated that the greatest forage kp in goats is likely to be c. 0·0569/h. The comparison with a previously published empirical equation containing data on cattle, sheep and goats, suggested that the distribution of the present empirical equation, adjusted for mean bias, is wider and that kp of goats might be similar to cattle and sheep when fed high amounts of forage under confinement conditions.
Evaluation and application of the CPM Dairy Nutrition model
- L. O. TEDESCHI, W. CHALUPA, E. JANCZEWSKI, D. G. FOX, C. SNIFFEN, R. MUNSON, P. J. KONONOFF, R. BOSTON
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- Journal:
- The Journal of Agricultural Science / Volume 146 / Issue 2 / April 2008
- Published online by Cambridge University Press:
- 30 November 2007, pp. 171-182
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The Cornell-Penn-Miner (CPM) Dairy is an applied mathematical nutrition model that computes dairy cattle requirements and the supply of energy and nutrients based on characteristics of the animal, the environment and the physicochemical composition of the feeds under diverse production scenarios. The CPM Dairy was designed as a steady-state model to use rates of degradation of feed carbohydrate and protein and the rate of passage to estimate the extent of ruminal fermentation, microbial growth, and intestinal digestibility of carbohydrate and protein fractions in computing energy and protein post-rumen absorption, and the supply of metabolizable energy and protein to the animal. The CPM Dairy version 3.0 (CPM Dairy 3.0) includes an expanded carbohydrate fractionation scheme to facilitate the characterization of individual feeds and a sub-model to predict ruminal metabolism and intestinal absorption of long chain fatty acids. The CPM Dairy includes a non-linear optimization algorithm that allows for least-cost formulation of diets while meeting animal performance, feed availability and environmental restrictions of modern dairy cattle production. When the CPM Dairy 3.0 was evaluated with data of 228 individual lactating dairy cows containing appropriate information including observed dry matter intake, the linear regression between observed and model-predicted milk production values indicated the model was able to account for 79·8% of the variation. The concordance correlation coefficient (CCC) was high (rc=0·89) without a significant mean bias (0·52 kg/d; P=0·12). The accuracy estimated by the CCC was 0·997. The root of mean square error of prediction (MSEP) was 5·14 kg/d (0·16 of the observed mean) and 87·3% of the MSEP was due to random errors, suggesting little systematic bias in predicting milk production of high-producing dairy cattle. Based upon these evaluations, it was concluded the CPM Dairy 3.0 model adequately predicts milk production at the farm level when appropriate animal characterization, feed composition and feed intake are provided; however, further improvements are needed to account for individual animal variation.