scholarly journals Lactation curve of Beetal goats in Pakistan

2013 ◽  
Vol 56 (1) ◽  
pp. 892-898
Author(s):  
A. Waheed ◽  
M. S. Khan
Keyword(s):  
Milk Yield ◽  
Model Parameters ◽  
Yield Data ◽  
Lactation Length ◽  
Lactation Curve ◽  
Rate Of Increase ◽  
The Mean ◽  
Rate Of Decline ◽  
Wood Model ◽  
Effect Of Age

Abstract. This study was accomplished with the objective to determine parameters of lactation curves in Beetal goats using Wood’s model. Therefore, milk yield data on 127 Beetal goats maintained at five different government farms were recorded from post-kidding to drying off of does. Wood model parameters were estimated using non-linear regression and individual curves were fitted. The characteristics/parameters of lactation curve were computed. The mean initial yield »a«, rate of increase »b« and rate of decline »c« parameters in Wood’s model for Beetal were 1,214.97, 0.3690 and 0.1196, respectively with R2 value of 98.2 %. The value of percent squared bias (PSB) and the persistency were 0.13 and 60.2%, respectively with mean square error value of 38.45. Flock effect was a significant (P<0.01) source of variation for all the lactation curve parameters, PSB and persistency. Parity did not affect significantly any of the parameters. Type of birth significantly influenced parameter »a«, Time to reach peak (TPY) and lactation milk yield (LMY). Sex of kid also did not affect significantly any of the parameters. Age of doe was significant for parameters »a«, »b«, »c«. Quadratic effect of age was non-significant for all parameters and characteristics. Lactation length significantly affected parameter »a«, »b« and LMY.

Forage to concentrate ratio in Jonica breed goats: influence on lactation curve and milk composition

2009 ◽  
Vol 76 (1) ◽  
pp. 124-128 ◽  
Author(s):  
Vincenzo Tufarelli ◽  
Marco Dario ◽  
Vito Laudadio
Keyword(s):  
Energy Level ◽  
Milk Yield ◽  
Dry Matter ◽  
High Energy ◽  
Milk Composition ◽  
High Energy Level ◽  
Lactation Curve ◽  
Rate Of Increase ◽  
Rate Of Decline ◽  
Dietary Treatments

The aim of the work is to evaluate the effects of different forage to concentrate rations on milk yield, composition and renneting properties of milk of Jonica breed goats. Twenty-four Jonica goats received diets with forage to concentrate ratio of 35/65, 50/50 or 65/35, providing respectively a low, medium and high energy level. Goats were divided into three homogenous groups and confined in individual pens for 152 days to assess the daily feed intake and milk yield and composition. The main conclusions show that animal body weight did not change significantly with the increasing levels of forage, whereas significant differences (P<0·05) for daily dry matter intake were observed in relation to the evolution of lactation. Milk production was influenced (P<0·05) by dietary treatments and was higher in the diet with the greatest energy level. Forage to concentrate ratios did not significantly affect milk characteristics, milk renneting properties, initial production, rate of increase until reaching the peak and rate of decline after peak production. However, the day of peak production and peak production of goats were linearly reduced when the level of forage increased within the diet. In conclusion, the results indicate that both forage to concentrate ratio and energy level improve goat's production without influencing the milk composition.

Reproductive rates and milk yield of Kenana cattle in Sudan

1960 ◽  
Vol 55 (2) ◽  
pp. 183-188 ◽  
Author(s):  
K. A. Alim
Keyword(s):  
Milk Yield ◽  
Average Length ◽  
Dairy Herd ◽  
Lactation Length ◽  
Coefficients Of Variation ◽  
Rate Of Increase ◽  
Close Relationship ◽  
The Mean ◽  
Reproductive Rates ◽  
Calving Intervals

An analysis has been made of the reproductive rates and milk yield of Kenana cattle in a closed dairy herd in Sudan.The average age at first calving was 38·4 months and calvings were most frequent between September and December.The average length of productive herd life of cows was 5·42 lactations.The average interval between successive calvings was 395 days, and this was influenced by years and age.The mean generation interval was 6·72 years.The average milk yield in 224 days was 338 gal. with a standard deviation of 152 gal.There was a close relationship between milk yield and lactation length; r = 0·866 ± 0·013.Milk yield increased by age until the fourth lactation when it was about 137% of the first lactation. The rate of increase in yield between first and second lactation was highest and amounted to 22%.Year of record had a pronounced effect on milk yield.Month of calving had a slight effect on milk yield.The repeatability estimates of single records milk yield, calving intervals, lactation periods and dry periods were 0·432 ± 0·046, 0·058 ± 0·059, 0·192 ± 0·058 and 0·069 ± 0·065, respectively.The increase in repeatability estimates between earlier and later successive milk yield records was accompanied by a decrease in the coefficients of variation of these records.The heritability of a single record milk yield was 0·239 ± 0·245.The rate of annual genetic superiority in milk yield of dams of cows and dams of bulls was found to be 0·74% of the herd average.

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.

PSV-14 Using Bayesian Hamiltonian Monte Carlo and a nonlinear model for the estimation of genetic parameters for lactation curves in goats

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 305-307
Author(s):  
Andre C Araujo ◽  
Leonardo Gloria ◽  
Paulo Abreu ◽  
Fabyano Silva ◽  
Marcelo Rodrigues ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Milk Yield ◽  
Nonlinear Model ◽  
Genetic Parameters ◽  
Model Parameters ◽  
Promising Alternative ◽  
Hamiltonian Monte Carlo ◽  
Heritability Estimates ◽  
Correlated Parameters ◽  
Wood Model

Abstract Hamiltonian Monte Carlo (HMC) is an algorithm of the Markov Chain Monte Carlo (MCMC) method that uses dynamics to propose samples that follow a target distribution. This algorithm enables more effective and consistent exploration of the probability interval and is more sensitive to correlated parameters. Therefore, Bayesian-HMC is a promising alternative to estimate individual parameters of complex functions such as nonlinear models, especially when using small datasets. Our objective was to estimate genetic parameters for milk traits defined based on nonlinear model parameters predicted using the Bayesian-HMC algorithm. A total of 64,680 milk yield test-day records from 2,624 first, second, and third lactations of Saanen and Alpine goats were used. First, the Wood model was fitted to the data. Second, lactation persistency (LP), peak time (PT), peak yield (PY), and total milk yield [estimated from zero to 50 (TMY50), 100(TMY100), 150(TMY150), 200(TMY200), 250(TMY250), and 300(TMY300) days-in-milk] were predicted for each animal and parity based on the output of the first step (the individual phenotypic parameters of the Wood model). Thereafter, these predicted phenotypes were used for estimating genetic parameters for each trait. In general, the heritability estimates across lactations ranged from 0.10 to 0.20 for LP, 0.04 to 0.07 for PT, 0.26 to 0.27 for PY, and 0.21 to 0.28 for TMY (considering the different intervals). Lower heritabilities were obtained for the nonlinear function parameters (A, b and l) compared to its predicted traits (except PT), especially for the first and second lactations (range: 0.09 to 0.18). Higher heritability estimates were obtained for the third lactation traits. To our best knowledge, this study is the first attempt to use the HMC algorithm to fit a nonlinear model in animal breeding. The two-step method proposed here allowed us to estimate genetic parameters for all traits evaluated.

scholarly journals On designing the average lactation curve at the ascending phase

1962 ◽  
Vol 34 (1) ◽  
pp. 162-168
Author(s):  
Aarne Mäkelä
Keyword(s):  
Dairy Cows ◽  
Milk Yield ◽  
Lactation Period ◽  
Lactation Curve ◽  
The Mean ◽  
The Individual ◽  
Daily Milk Yield ◽  
Daily Milk

Comparisons are made between different methods to find the peak production (maximum daily milk yield) and methods to design the average lactation curve at the ascending phase in dairy cows. It was noted that in order to determine the height and location of the maximal producing capacity of a cow in a known lactation period, it is preferable to choose the peak production as a mean of three subsequent best days. It was also noted that the usual methods for drawing the average lactation curves do not give a true picture of the height and location of the peak. The author suggests a method for determining the average lactation curve at the ascending phase by using the averages of both milk productions and times involved in reaching the peak and known fractions (e.g. 1/8, 1/4, 1/2, 3/4, and 5/4) of it. In this lactation curve the peak production is the mean of the peaks of individual cows, and the time involved in reaching it is the mean of the durations of the ascending phases of the individual cows.

scholarly journals Milk production and lactation length in Ankole cattle and Ankole crossbreds in Rwanda

2020 ◽  
Vol 52 (6) ◽  
pp. 2937-2943
Author(s):  
Maximillian Manzi ◽  
Lotta Rydhmer ◽  
Martin Ntawubizi ◽  
Claire D’Andre Hirwa ◽  
Callixte Karege ◽  
...  
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Mixed Linear Model ◽  
Yield Data ◽  
Ankole Cattle ◽  
Lactation Length ◽  
Breed Group ◽  
Significant Difference ◽  
Daily Milk Yield ◽  
Daily Milk

Abstract This study assessed daily milk yield (DMY), 100-day (MY100), and 305-day (MY305) milk yield, and lactation length (LL) in purebred Ankole cattle and Ankole crossbreds, and the influence of environmental factors on these traits. Milk yield data were obtained for 865 cows and 1234 lactations and analyzed using a mixed linear model. The overall least squares mean of DMY, MY100, and MY305 across breed groups was 2.7 L (N = 1234, SD = 1.7), 262 L (N = 959, SD = 176), and 759 L (N = 448, SD = 439), respectively, while the average lactation length was 256 days (N = 960, SD = 122). All factors included (breed group, season and year of calving, and parity) were significant for yield traits, except season of calving for MY305. First-parity cows had the lowest milk production, and fourth-parity cows the highest. For all traits, pure Ankole cows had the lowest milk yield. Among the crossbreds, there was no significant difference between Ankole × Friesian, Ankole-Jersey mother × Sahiwal sire, and Ankole-Sahiwal mother × Jersey sire, or between Ankole × Sahiwal and Ankole-Sahiwal mother × Sahiwal sire. It was concluded that Ankole crosses with Friesian or Jersey can be beneficial, even under a management system of limited nutrition as in Rwanda.

Milk yield and mammary function in dairy cows milked four times daily

1990 ◽  
Vol 57 (3) ◽  
pp. 285-294 ◽  
Author(s):  
J. Eric Hillerton ◽  
Christopher H. Knight ◽  
Alan Turvey ◽  
Stephen D. Wheatley ◽  
Colin J. Wilde
Keyword(s):  
Milk Yield ◽  
Enzyme Activities ◽  
Milk Protein ◽  
Lactating Cows ◽  
Milk Protein Content ◽  
Significant Difference ◽  
The Mean ◽  
Milking Frequency ◽  
Rate Of Decline

SummaryGroups of lactating cows and heifers were milked four times daily in two diagonally opposed glands for 4 weeks, and the effects on milk yield studied relative to twice-daily milked glands as controls. Mammary enzyme activities, in vitro synthesis rates of milk constituents and histological scoring were determined in mammary biopsy samples obtained at the end of this period. These were used for assessment of mammary function. Frequent milking increased milk yield only in the treated glands, the contralateral control glands continuing to decline in yield at ~ 2%/week. There was no significant difference in response between cows and heifers; the mean increase in yield was 10·4%. The rate of decline in milk yield tended to decrease with frequent milking, to ~ 1%/week. Consequently the yield of the treated glands continued to be elevated above that of the controls for some time after reversion to overall twice daily milking. Milk protein content was increased slightly by frequent milking. Mammary enzyme activities were ~ 18% higher in the treated glands than in the controls. Synthesis rates of lactose, casein and total protein were unaffected by milking frequency, but were all lower in the gland selected for the second biopsy, reflecting the reduction in milk yield caused by the first biopsy. DNA synthesis was increased by milking frequency, as were the size and number of epithelial cells in histological sections.

The influence of liveweight at calving on milk production in Friesian heifers

1965 ◽  
Vol 32 (2) ◽  
pp. 135-141 ◽  
Author(s):  
B. Ridler ◽  
W. H. Broster ◽  
D. R. Westgarth
Keyword(s):  
Milk Yield ◽  
Positive Relationship ◽  
Final Analysis ◽  
Regression Equations ◽  
Mean Values ◽  
Significant Positive Relationship ◽  
Lactation Length ◽  
Group A ◽  
The Mean ◽  
Maintenance Requirements

SummaryRecords of 81 heifers, daughters of 6 bulls, were examined to determine the regressions of milk yield, corrected for lactation length, on initial liveweight and age at calving.Age was found to have no significant effect and was discarded in the final analysis.The regression equations were similar for the different groups of half-sibs, except for one group whose members had not been fed according to milk yield. After removal of this group, a highly significant positive relationship between lactation yield and liveweight at calving was found ‘within bull groups’. The mean values of groups of halfsibs did not show this relationship, and significant differences in milk yield still persisted between groups after adjustment for liveweight differences.It was concluded that herd improvement by choosing heifers solely on the basis of liveweight shortly after calving appears unlikely to be effective unless the sire's potential is known and the feeding during lactation takes into account the greater maintenance requirements of heavier animals.

Application of the Wood model to analyse lactation curves of organic dairy sheep farming

2014 ◽  
Vol 54 (10) ◽  
pp. 1609 ◽  
Author(s):  
Juan Carlos Ángeles Hernández ◽  
Octavio Castelán Ortega ◽  
Benito Albarrán Portillo ◽  
Hugo H. Montaldo ◽  
Manuel González Ronquillo
Keyword(s):  
Milk Yield ◽  
Goodness Of Fit ◽  
Evaluation Criteria ◽  
Coefficient Of Determination ◽  
Dairy Sheep ◽  
Organic System ◽  
Dairy Ewes ◽  
Lactation Curve ◽  
Total Milk ◽  
Wood Model

The aim of the present study was to evaluate the performance of the Wood model to describe the characteristics of lactation curves of dairy ewes under organic management in Mexico. In total, 4861 weekly test-day milk yield records from 194 lactations of crossbred dairy ewes were analysed to assess the performance of an empirical model to fit their lactation curve. We used the mathematical model proposed by Wood. The evaluation criteria were the correlation coefficient (r) between the values of total milk yield observed and estimated, the coefficient of determination (R2), and the mean square prediction error (MSPE). In addition, the peak yield (PYest) and time at peak yield (PTest) were calculated. The Wood model showed adequate goodness of fit (r = 0.95, R2 = 0.92 and MSPE = 0.024). The Wood model detected that 52.06% of lactation curves had a continuously decreasing shape (atypical curve), probably as a consequence of the characteristic management of the organic system, mainly due to the genotype used and the nutritional management. Residuals were greater for atypical curves than for typical ones, indicating differences in the ability of the Wood model to fit the two types of shapes. In typical curves, the Wood model showed adequate estimates of total milk yield and time at peak yield. The peak yield was underestimated both in typical and atypical curves. The Wood model in atypical curves underestimated the time at peak yield and milk yields in late lactation. The Wood model showed a reasonable fit of lactation curve in dairy sheep in organic systems but presented deficiencies of fit in atypical curves; therefore, estimates should be interpreted carefully.

An investigation of the changes in sites of milk storage in the bovine udder over two lactation cycles

1993 ◽  
Vol 57 (03) ◽  
pp. 379-384
Author(s):  
R. J. Dewhurst ◽  
C. H. Knight
Keyword(s):  
Milk Yield ◽  
Total Yield ◽  
Significant Interaction Effect ◽  
Stage Of Lactation ◽  
Lactation Curve ◽  
Significant Difference ◽  
Total Milk ◽  
Sources Of Variation ◽  
Rate Of Decline ◽  
Daily Milk Yield

AbstractThe objective of this work was to investigate phenotypic sources of variation in the sites of storage of milk within the udder. Ten primiparous and 10 multiparous dairy cows were studied over two successive lactations in order to investigate the effects of age, parity and stage of lactation. Cistern and alveolar milk volumes were estimated at a standard 8 h after a normal morning milking by catheter drainage and machine milking with oxytocin respectively. Measurements were made at approximately 9, 20, 30 and 42 weeks of the initial lactation and weeks 1, 4, 7, 10, 20 and 34 of the subsequent lactation. In the initial lactation, there was a significant difference between primiparous and multiparous animals in the rate of decline of total daily milk yield (P&lt; 0·001). Cistern milk yield (kg/8 h) from multiparous animals declined over the lactation whilst that for primiparous animals was maintained. The effect was shown as a significant interaction effect (P&lt; 0·05). For both multiparous and primiparous animals cistern proportion (cistern yield divided by total milk yield at 8h after a normal milking), increased over the lactation (P&lt; 0·001). This was largely a consequence of the reduced total milk yield. Eleven animals were studied through the subsequent lactation. Cistern yield followed a lactation curve of similar form to that for total yield. The decline in cistern yield over this lactation was much greater than the decline with multiparous animals in the previous year. This may, in part, reflect a faster decline in total daily yield. Stage of lactation and parity must be taken into account if a standardized evaluation of cistern characteristics is to be obtained.

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