12 research outputs found
Mathematical Modeling of Lactation Curves: A Review of Parametric Models
The mathematical representation of milk production against time represents one of the most successful applications of mathematical modeling in agriculture. Models provide summary information, which is useful in making management and breeding decisions. Several empirical mathematical functions have been proposed to describe the lactation curve of dairy cattle differing in mathematical properties, in the number of parameters and in their degree of relationships with the main features of a typical lactation pattern, such as peak yield, time at peak and persistency. This review gives an overview of the parametric models used to fit of lactation curves in dairy cattle. Parametric models are those that found large application to fit the lactation curves, basically due to their limited mathematical complexity, and their abilities to fit a large kind of curves. Models to describe the lactation curve have been classified into two main groups: linear and nonlinear models. Nonlinear parametric functions have represented the preferred tools for modeling lactation curves with the main aim of predicting yields and parameters describing the shape of the curve in addition to important parameters such as peak yield and persistency. Nonlinear models need iterative techniques to be solved. Different iterative methods frequently employed in nonlinear regression models are Marquardt, Newton, Gauss and Dud. Wood model was the most popular parametric model with the largest application can be found in the immediate and easy understanding of relationships between its parameters and main curvatures of the lactation pattern
Dairy Cattle Welfare Status Measured by Animal-Linked Parameters Under Tunisian Rearing Conditions
Effects of Environmental Factors on Milk Yield, Lactation Length and Dry Period in Tunisian Holstein Cows
Dairy Cattle Welfare Status Measured by Animal-Linked Parameters Under Tunisian Rearing Conditions
Parámetros fenotĂpicos y genĂ©ticos de caracteres reproductivos en vacas Holstein en TĂşnez
Various factors influencing reproduction in dairy Holstein cows were
routinely evaluated and genetic parameters were estimated for four
traits to assess fertility of artificially inseminated cows: Calving to
first service interval (CFSI), calving interval (CI), calving to
conception interval (CCI) and number of services per conception (NSC).
Data used in this investigation consisted of records of insemination
and calving events on Tunisian Holstein cows. The data included records
from 1994 to 2003 in 150 herds. The aim of the study was to investigate
the effects of non-genetic factors on reproductive traits and estimate
their heritabilities. The factors examined were: month and year of
calving, herd, parity, and year-month of calving. The effect of month
and year of calving (or insemination), herd, parity and year-month of
calving were included in the model and were significant (P < 0.01)
except for the number of lactations that does not have an effect on the
NSC. A decreasing efficiency in cow fertility was observed over the
last years, with a longer day for first service interval. Heritability
for fertility traits was low ranging from 0.027 for NSC to 0.067 for
CI. The results suggested that more attention should be paid to herds
with too low fertility traits and that monitoring and intervention
schemes should be tested in research approaches.Se evaluaron de manera rutinaria diferentes factores que influyen en la
reproducciĂłn de las vacas lecheras Holstein y se estimaron los
parámetros genéticos de cuatro caracteres para evaluar la
fertilidad de las vacas inseminadas artificialmente: el intervalo de
parto a primer servicio (IPPS), el intervalo entre partos (IP), el
intervalo de parto a concepciĂłn (IPC) y el nĂşmero de
servicios por concepciĂłn (NSC). Los datos utilizados en esta
investigaciĂłn consistieron de registros de eventos de
inseminaciĂłn y partos en vacas Holstein de TĂşnez. Los
registros fueron tomados desde 1994 hasta 2003 en 150 rebaños para
estudiar los efectos de factores no genéticos y estimar las
heredabilidades de los caracteres anteriormene señalados de
fertilidad. Los factores examinados fueron: mes y año de parto,
rebaño, paridad y año-mes de parto. El efecto del mes y
año de parto (o inseminación), rebaño, paridad y
año-mes de parto se incluyeron en el modelo y fueron
significativos (P <0,01) con excepciĂłn del nĂşmero de
lactancias que no tiene un efecto sobre el NSC. Se observe una
eficiencia decreciente en la fertilidad de las vacas en los
Ăşltimos años, con un dĂa más largo para el
intervalo del primer servicio. La heredabilidad para los caracteres de
la fertilidad fue baja en un rango de 0,027 para NSC a 0,067 para el
interval entre partos. Los resultados sugieren que deberĂa
prestarse más atención a los rebaños con rasgos muy
bajos de fertilidad y que los esquemas de vigilancia e
intervenciĂłn deberĂan ser evaluados con enfoques de
investigaciĂłn
Autonomous and Dynamic Inter-Cell Interference Coordination Techniques for Future Wireless Networks
International audienc
A Dynamic Inter-cellular Bandwidth Fair Sharing scheduler for future wireless networks
International audienc
A Dynamic Transmission Strategy Based on Network Slicing for Cloud Radio Access Networks
International audienc
Phenotypic and genetic parameters of reproductive traits in Tunisian Holstein cows
Various factors influencing reproduction in dairy Holstein cows were routinely evaluated and genetic parameters were
estimated for four traits to assess fertility of artificially inseminated cows: Calving to first service interval (CFSI), calving
interval (CI), calving to conception interval (CCI) and number of services per conception (NSC). Data used in this
investigation consisted of records of insemination and calving events on Tunisian Holstein cows. The data included records
from 1994 to 2003 in 150 herds. The aim of the study was to investigate the effects of non-genetic factors on reproductive
traits and estimate their heritabilities. The factors examined were: month and year of calving, herd, parity, and year-month
of calving. The effect of month and year of calving (or insemination), herd, parity and year-month of calving were included
in the model and were significant (P < 0.01) except for the number of lactations that does not have an effect on the NSC. A
decreasing efficiency in cow fertility was observed over the last years, with a longer day for first service interval.
Heritability for fertility traits was low ranging from 0.027 for NSC to 0.067 for CI. The results suggested that more attention
should be paid to herds with too low fertility traits and that monitoring and intervention schemes should be tested in
research approaches.Se evaluaron de manera rutinaria diferentes factores que influyen en la reproducciĂłn de las vacas lecheras Holstein y se
estimaron los parámetros genéticos de cuatro caracteres para evaluar la fertilidad de las vacas inseminadas artificialmente:
el intervalo de parto a primer servicio (IPPS), el intervalo entre partos (IP), el intervalo de parto a concepciĂłn (IPC) y el
nĂşmero de servicios por concepciĂłn (NSC). Los datos utilizados en esta investigaciĂłn consistieron de registros de eventos
de inseminación y partos en vacas Holstein de Túnez. Los registros fueron tomados desde 1994 hasta 2003 en 150 rebaños
para estudiar los efectos de factores no genéticos y estimar las heredabilidades de los caracteres anteriormene señalados de
fertilidad. Los factores examinados fueron: mes y año de parto, rebaño, paridad y año-mes de parto. El efecto del mes y año
de parto (o inseminación), rebaño, paridad y año-mes de parto se incluyeron en el modelo y fueron significativos (P <0,01)
con excepciĂłn del nĂşmero de lactancias que no tiene un efecto sobre el NSC. Se observe una eficiencia decreciente en la
fertilidad de las vacas en los Ăşltimos años, con un dĂa más largo para el intervalo del primer servicio. La heredabilidad para
los caracteres de la fertilidad fue baja en un rango de 0,027 para NSC a 0,067 para el interval entre partos. Los resultados
sugieren que deberĂa prestarse más atenciĂłn a los rebaños con rasgos muy bajos de fertilidad y que los esquemas de
vigilancia e intervenciĂłn deberĂan ser evaluados con enfoques de investigaciĂłn