scholarly journals Comparison of Mathematical Models Applied to F1 Dairy Sheep Lactations in Organic Farm and Environmental Factors Affecting Lactation Curve Parameter

2013 ◽  
Vol 26 (8) ◽  
pp. 1119-1126 ◽  
Author(s):  
J. C. Angeles-Hernandez ◽  
B. Albarran-Portillo ◽  
A. V. Gomez Gonzalez ◽  
N. Pescador Salas ◽  
M. Gonzalez-Ronquillo
Keyword(s):  
Environmental Factors ◽  
Mathematical Models ◽  
Dairy Sheep ◽  
Factors Affecting ◽  
Organic Farm ◽  
Curve Parameter ◽  
Lactation Curve

Genetic and environmental factors affecting some measures of yield and fertility in a registered Canadian Holstein dairy herd in Iran

2002 ◽  
Vol 2002 ◽  
pp. 190-190
Author(s):  
Ali Toosi
Keyword(s):  
Environmental Factors ◽  
Genetic Parameters ◽  
Dairy Herd ◽  
Cattle Breeding ◽  
Factors Affecting ◽  
Lactation Curve ◽  
Dairy Cattle Breeding ◽  
Important Trait ◽  
Genetic And Environmental Factors ◽  
Production Characteristics

Milk production is the most important trait in dairy cattle breeding. Measures of additional traits are also important. Traits of lactation curve are important in their relation to production characteristics. The two major reasons for which dairy cows are disposed are fertility problems and low milk yield (Hansen et al.,1983). The objectives of this study were 1) To evaluate effects of some environmental factors on some measures of yield and fertility, and 2) To estimate genetic parameters for these traits applying REML procedures under sire model.

scholarly journals Accurate mathematical models to describe the lactation curve of Lacaune dairy sheep under intensive management

animal ◽  
2013 ◽  
Vol 7 (6) ◽  
pp. 1044-1052 ◽  
Author(s):  
L. Elvira ◽  
F. Hernandez ◽  
P. Cuesta ◽  
S. Cano ◽  
J.-V. Gonzalez-Martin ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Intensive Management ◽  
Dairy Sheep ◽  
Lactation Curve

Factors affecting the lactation curves of intensively managed sheep based on a clustering approach

2013 ◽  
Vol 80 (4) ◽  
pp. 439-447 ◽  
Author(s):  
Laura Elvira ◽  
Fernando Hernandez ◽  
Pedro Cuesta ◽  
Santiago Cano ◽  
Juan-Vicente Gonzalez-Martin ◽  
...  
Keyword(s):  
Milk Yield ◽  
Clustering Analysis ◽  
Dairy Sheep ◽  
Dry Period ◽  
Factors Affecting ◽  
Lactation Curve ◽  
Total Milk ◽  
Clustering Approach ◽  
Intensively Managed ◽  
Selection Of

This study investigated factors affecting milk production and lactation curves from complete lactations of Lacaune dairy sheep. Animals were part of a single flock under intensive management and were milked twice daily starting at lambing. The results of the analyses of 7788 complete lactations showed an average total milk yield of 434±183 l from lactations 234±63 d long, with an average lambing interval of 302±65 d. A Pollott additive mathematical model was used to estimate complete lactation curves. Clustering analysis identified four lactation types among Lacaune dairy sheep differing mainly in productivity i.e. milk yield per lactation (MY) and length of lactation (DIM). The so-called SL type involved short, less productive lactations (n=2137; 27·4%; MY=222±75·5 l and DIM=182±52·9 d). The SN type involved short lactations of normal productivity (n=2039; 26·2%; MY=396±73·7 l and DIM=205±33·1 d). The LP type involved long and productive lactations (n=2169; 27·9%; MY=487±70·5 l and DIM=265±40·7 d), while the LVP type included long and extremely productive lactations (n=1443; 18·5%; MY=694±114·0 l and DIM=295±54·7 d). Sheep showing the best lactation curves were usually younger than other sheep, and they had higher yield during the previous lactation, a shorter previous dry period (55±50·4 for LP and 61±55·0 d for LVP types) and longer lambing intervals. In addition, they tended to be born in September and to lamb in March, October and December. Sheep were remarkably stable in their lactation curve behaviour: the curve type observed for the first lactation was highly likely to persist in subsequent lactations (P<0·0001). These results suggest that farmers can use the shape of the first lactation curve to guide their selection of ewes for breeding and retention on the farm, thereby improving flock productivity.

Environmental factors affecting reproducibility of bioremediation field assays in Antarctica

2020 ◽  
Vol 169 ◽  
pp. 102915 ◽  
Author(s):  
L.M. Martínez Álvarez ◽  
L.A.M. Ruberto ◽  
J.M. Gurevich ◽  
W.P. Mac Cormack
Keyword(s):  
Environmental Factors ◽  
Factors Affecting
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