Factors affecting goat milk yield and its composition

Abstract

ABSTRACT:The aim of the paper was to prove the accuracy of various statistical models of variance analysis for estimation of systematic factors that influence milk yield and fat and protein content in dairy goats. Data on daily milk production recorded by methods AT, AC or A4 for the population of Czech White Shorthaired Goats over 1992-2002 was used for calculations. A total of 78 736 test day from 6 234 goats were analysed. Average daily milk production was 3.09 kg with 3.72% of fat and 2.84% of protein. Variability of examined traits was significantly influenced by effects of herd-year or herd-test day, li�er size, parity, season of kidding, stage of lactation and the combined effect parity-year-season of kidding. The variants of model equations in which complex effects of herd-year were replaced by effects of herd-test day showed higher values of reliability for the three traits analysed.Keywords: Czech White Shorthaired Goat; fat; protein; lactation curve; test day 466Original Paper Czech J. Anim. Sci., 49, 2004 (11): 465-473 day Animal Model for BVE in dairy goats. Milerski et al. (1999) found considerable differences in the evaluation of individual animals between the system of evaluation of dairy goats presently used in the Czech Republic and BVE done by BLUP Animal Model. MATERIAL AND METHODSData from the official milk recording of the Czech White Shorthaired breed of goats provided by the Sheep and Goat Breeders Association (SCHOK) was used as the basic material for our calculations. The analysed data were recorded in the period from 1992 to 2002. Daily milk production was recorded by methods AT, AC or A4 (ICAR, 2001). Although the analysed data were recorded in production operations, several fixed effects were included in the model. The most marked effects will be chosen using the ordinary Least Squares Method and the procedure GLM (SAS, 1996).Several checks of performance records were carried out in order to exclude logical inconsistencies and biological improbabilities: (a) Age at first kidding had to be at least 275 days. (b) Difference between lactation number and period (in years) from birth to the 31/12/n (n = production year): 0.5-2 years. (c) Test-day records included for year n had to be between the dates 1st October n-1 and the 31st March n+1. (d) Kidding date had to be between the dates 1st October n-1 and the 30th September n. Other used criteria are shown in Table 1. Poor quality data were excluded from the followings computations. The original performance record database included 87 736 test-day records. The number of data considerably diminished a�er the introduction of the above-mentioned criteria, a total of 78 736 records of daily milk production, 77 536 records of fat percentage and 78 269 records of protein percentage in milk from 6 234 goats were finally analysed.The effects of herd, test day, number and stage of lactation, production year, kidding season and li�er size were tested using the followings five models: e ijklm = random residual RESULTS AND DISCUSSIONMeans and standa...

Factors affecting milk yield and ewe's lactation curves estimated with test-day models

“…For Lacaune, there was a highly significant (P < 0.01) difference between lactations starting in February and March (1.145 vs. 1.036 kg). A lower daily milk yield found for lactations starting in January and February (Improved Valachian) is in agreement with findings of Ciappesoni et al (2004) for White Shorthaired goat, who explained this fact by poor quality feeding and change from winter to summer ration. An opposite trend in Tsigai and Lacaune (milk yield lower for lactations starting in March) is in agreement with findings of CappioBorlino et al (1997) for Valle del Belice.…”

“…Differences in the first three lactations found for the remaining two breeds (less than 10%) were in accordance with findings of Gonzalo et al (1994), Christodoulou et al (1997), El-Saied et al (1998) and Margetín et al (1998). However, Cappio-Borlino et al (1997), Margetín and Milerski (2000) and Ciappesoni et al (2004) found differences in the first three lactations between 13 and 17% for Valle del Belice ewes; 11 and 15% and 18 and 25% for White Shorthaired goats kept in Slovakia and the Czech Republic.…”

Effect of different protein and energy levels in concentrate diets on nutrient intake and milk yield of Saanen x Etawah Grade goats

“…The different levels of protein and energy response on milk yields and milk composition yields between different research reports might be due to many factors such as forage to concentrate ratio (Tufarelli et al 2009;Park et al 2010), breed and traits (Ciappesoni et al 2004). But forage to concentrate ratio in this trial might not affect milk yield and milk composition since their rations were not significantly different as shown in Table 2.…”

Factors affecting goat milk fat yield

“…Similar results were also obtained by Croatian scientists B. Mioč et al (2008) who determined that the highest milk fat content was that of goats of the 5th and higher parities (3.47 ± 0.02%), though significant differences were not observed among goats of all parities: it fluctuated from 3.42 ± 0.02% (the third parity) to 3.47 ± 0.02% (the fifth and higher parities), respectively. During the research conducted by G. Ciappesoni et al (2004), a slight increase of the milk fat content was established depending on lactation (from 3.52% during the first parity to 3.55% during the fourth and further parities, p < 0.05). Nigerian scientists D. Zahraddeen et al (2007) determined that the fat content was highest in the third parity (5.54 ± 0.03%) followed by the second parity (4.73 ± 0.03%) and least in the first parity (4.39 ± 0.02%), whereas D. Carnicella et al (2008) determined that an insignificant but statistically higher (0.1% (p < 0.001)) milk fat content was in the case of goats of the first parity as compared to that of goats of the second, third and further parities.…”