Factors affecting milk yield and lactation curve fitting in the creole sheep of Chiapas-Mexico

2005 ◽  
Vol 58 (3) ◽  
pp. 265-273 ◽  
Author(s):  
Marisela Peralta-Lailson ◽  
Arturo Ángel Trejo-González ◽  
Pastor Pedraza-Villagómez ◽  
José M. Berruecos-Villalobos ◽  
Carlos G. Vasquez
Keyword(s):  
Milk Yield ◽  
Curve Fitting ◽  
Factors Affecting ◽  
Lactation Curve ◽  
Fitting In

Factors affecting milk production in Improved Awassi dairy ewes

2000 ◽  
Vol 71 (3) ◽  
pp. 607-615 ◽  
Author(s):  
E. Gootwine ◽  
G. E. Pollott
Keyword(s):  
Milk Production ◽  
Litter Size ◽  
Milk Yield ◽  
Intensive Management ◽  
Short Term ◽  
Artificial Rearing ◽  
Factors Affecting ◽  
Lactation Curve ◽  
Total Milk ◽  
Term Variation

AbstractThis study investigated the factors affecting milk production and lactation curve parameters from the complete lactations of Awassi dairy sheep. The animals were kept in a single flock under intensive management and milked twice daily starting at lambing. Lambs were removed from the ewes at birth into an artificial rearing unit. The results of the analyses of 3740 complete lactations showed a mean litter size of 1·28 lambs born per ewe lambing and average total milk yield of 506 l from lactations 214 days in length and with an average lambing interval of 330 days. Mean lactation number was 3·71 and ewes conceived on average in the 6th month of the lactation. The lactations peaked on day 45 at a yield of 3·44 l. The maximum milk secretion potential of the ewes was 3·9 l/day, with milk yield increasing at 62 g/day mid way between lambing and peak yield and declining at 16·5 g/day mid way between peak and the end of lactation. Age at first lambing, lactation number, litter size, month of lambing and month of conception during the lactation had significant effects (P < 0·05) on some or all of the lactation parameters investigated. Relatively high milk yield was obtained in lactations starting in the January to March period. The monthly effect on milk production was explained by significant (P < 0·05) heat load and photoperiod effects. High milk production was found to have a significant (P < 0·05) adverse effect on reproductive performance. Conception followed a significant (P < 0·05) short term variation in milk production.

scholarly journals Factors affecting milk yield and ewe’s lactation curves estimated with test-day models

2011 ◽  
Vol 51 (No. 11) ◽  
pp. 483-490 ◽  
Author(s):  
M. Oravcová ◽  
M. Margetín ◽  
D. Peškovičová ◽  
J. Daňo ◽  
M. Milerski ◽  
...  
Keyword(s):  
Linear Model ◽  
Litter Size ◽  
Milk Yield ◽  
Fixed Effects ◽  
General Linear Model ◽  
Yield Variability ◽  
Factors Affecting ◽  
Lactation Curve ◽  
Daily Milk Yield ◽  
Daily Milk

Test-day records of purebred Tsigai, Improved Valachian and Lacaune ewes were analysed with a general linear model in order to investigate the effects of flock-test day, lactation number, days in milk, litter size and month of lambing. In total, 121 576 (Tsigai), 247 902 (Improved Valachian) and 2 196 (Lacaune) test-day records gathered over the period 1995&ndash;2005 were included in the analyses. Average daily milk yields were 0.604 &plusmn; 0.279 kg (Tsigai), 0.595 &plusmn; 0.243 kg (Improved Valachian) and 1.053 &plusmn; 0.475 kg (Lacaune). The significant (P &lt; 0.05) or highly significant (P &lt; 0.01) effects of flock-test day, lactation number (except for Lacaune), days in milk, litter size (except for Lacaune) and month of lambing (either fixed effects or covariates) tested by Fisher&rsquo;s tests were shown. The model explained about 50% of daily milk yield variability, with coefficients of determination as follows: 0.479 for Improved Valachian; 0.487 for Tsigai; 0.537 for Lacaune. Differences in estimated least-squares means were tested using multiple-range Scheffe&rsquo;s tests. A lower daily milk yield was found for the first lactation, single litter and lactations starting in March in comparison with daily milk yield for the second and third lactations (except for Lacaune), multiple litter and lactations starting in January and February (except for Improved Valachian). Ali-Schaeffer regression adopted for sheep was used for the fitting of lactation curve according to breed. &nbsp;

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.

The effect of environment and heredity on lactation. II. Persistency of lactation

1951 ◽  
Vol 41 (1-2) ◽  
pp. 89-93 ◽  
Author(s):  
P. Mahadevan
Keyword(s):  
Milk Yield ◽  
Statistical Study ◽  
Total Production ◽  
Present Material ◽  
Factors Affecting ◽  
South West ◽  
Lactation Curve ◽  
Numerical Expression

1. A statistical study of factors affecting variation in persistency of lactation has been made using 5000 lactation records from twelve leading herds of Ayrshire cattle in south-west Scotland for the period 1930–9.2. It is suggested that a satisfactory numerical expression for the shape of the lactation curve could be obtained from the formula, Persistency = where A is the milk yield during the first 180 days and B is the initial milk yield, namely, the milk yield during the first ten weeks of lactation.3. The interrelationships of persistency, initial milk yield and 180-day milk yield showed that these three characteristics are positively correlated with one another on a between cows within herd basis. This meant that it should be possible to combine high initial milk yield with high persistency to obtain increased total production.4. The effect of month of calving on persistency of lactation varied significantly between herds. On the average, the highest persistency was attained by cows calving in the winter, and the lowest by summer calvers.5. The variation of persistency with age showed that it is necessary to correct for the high persistency of first calvers when comparing cows with different lactations.6. The average repeatability of persistency was 0.242 in the present material, while heritability was of the order of 0.10–0.15.7. It has been concluded that improved feeding and management would bring about the greatest returns in the direction of improved persistency.

Modeling the lactation curve for test-day milk yield in Murciano-Granadina goats

2002 ◽  
Vol 46 (1) ◽  
pp. 29-41 ◽  
Author(s):  
C Fernández ◽  
A Sánchez ◽  
C Garcés
Keyword(s):  
Milk Yield ◽  
Lactation Curve

Factors affecting milk yield and prolificacy of Karagouniko sheep in West Thessaly (Greece)

1990 ◽  
Vol 24 (2) ◽  
pp. 181-186 ◽  
Author(s):  
I Hatziminaoglou ◽  
A Georgoudis ◽  
A Karalazos
Keyword(s):  
Milk Yield ◽  
Factors Affecting

The control of appetite in lactating cows

1972 ◽  
Vol 14 (3) ◽  
pp. 263-281 ◽  
Author(s):  
L. S. Monteiro
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Milk Yield ◽  
Closed Loop ◽  
Loop System ◽  
Closed Loop System ◽  
Lactating Cows ◽  
Body Reserves ◽  
Lactation Curve ◽  
Rate Of Increase

SUMMARYA closed-loop system is proposed for the control of voluntary food intake in lactating cows, and an expression is deduced relating the response of food intake to changes in milk yield and body-weight gain.A closed-loop system necessarily involves a delay in the response to changes in production. The rate of increase of food intake is there- fore slower than the rate of increase in milk yield. The consequent deficit in energy during the rising part of the lactation curve is met by the mobilization of body reserves, which are partly accounted for by losses in body weight. During the declining part of the lactation the delay effect leads to an excess of energy intake and to the replacement of body reserves and, consequently, of body weight.The expression deduced from the model was fitted to four different types of lactation curve corresponding to long and short lactations of Friesians and Jerseys fed ad libitum on a complete diet. The expected food intake based on the control model was contrasted with a linear regression model. The former gave a better account of the variation in food intake in all four types of lactation.The total change in body weight during lactation was partitioned between changes in weight due to the mobilization and replacement of reserves and gain directly attributable to food intake. There was, in general, good agreement between the observed losses in weight occurring at the beginning of lactation and those predicted from the mobilization of reserves for milk production.The physiological implications of the model and the values estimated for the parameters are discussed.

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