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Search Results: 1 - 10 of 1298 matches for " Vesna Gantner "
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Milk yield, milk composition and somatic cell count of dairy goats given n-3 unsaturated fatty acids diet supplement
Gantner Vesna,Kompan D.
Acta Veterinaria , 2012, DOI: 10.2298/avb1203281g
Abstract: Research of the effects of n-3 unsaturated fatty acids (PUFA, particularly eicosapentaenoic acid-EPA; α-linoleic acid-ALA; docosahexaenoic acid-DHA) on goat’s milk production (daily milk yield; daily fat, protein and lactose content) and somatic cell count and the persistence of this effect after terminated supplementation was conducted on 62 machine-milked Alpine breed goats kept at an indoor Alpine farm. After adoption period the animals were randomly allocated according to supplement addition into control group (G-4) with no added supplement and test groups (G-1; G-2; G-3) where a supplement containing PUFA was added over a period of five days. Measurements of milk yield and sampling (70 mL) for analysis of milk composition during the adoption period, supplementation period and first five days after supplementation were done every day at each milking (morning and evening). From the 5th to the 50th day of the after supplementation period, measurements and sampling occurred every fifth day. Based on the obtained results it could be concluded that the PUFA dietary addition alters the quantity and the quality of produced milk. DHA and EPA supplementation increase daily milk yield, while ALA supplementation induces a decrease of milk yield. When milk content is taken into consideration, the effects are contrary. Regarding somatic cell count, the highest effect on reduction was determined when ALA supplement was added. The mentioned effects persisted after the dietary supplement was withdrawn. The obtained results could be used in dietary supplementation planning in respect to the desired effects. Further research with the aim of determining the fatty acid composition of milk fat is needed.
Effect of α-linoleic acid supplementation in goat’s diet on milk yield, quality and somatic cell count
Vesna Gantner,Drago Kompan
Italian Journal of Animal Science , 2010, DOI: 10.4081/ijas.2009.s3.139
Abstract: Investigation of the effect of α-linoleic acid (ALA) on goat’s milk production (daily milk yield, fat and protein content) and somatic cell count (SSC) and the persistence of this effect after supplement termination was conducted on 32 Alpine breed goats kept on an indoor Alpine farm. After adaptation period the animals were randomly allocated according to treatment into control group (G0) with no added supplement and test group (G1) where supplement containing ALA was added over a period of five days. Measurements of milk yield and sampling for analysis of milk composition in adaptation period, treatment period and first five days of period after treatment occurred every day at each milking (morning and evening). From the 5th to the 50th day of the after treatment period, measurements and sampling occurred every fifth day. Based on the conducted research it could be concluded that supplementation had no effect on milk yield; it had low effect on milk components and significant effect on SSC. This could be used as a method of choice for reduction of SCC in goat’s milk.
Methods for early prediction of lactation flow in Holstein heifers
Vesna Gantner,Klemen Poto?nik,Kre?imir Kuterovac,Ranko Gantner
Mljekarstvo , 2010,
Abstract: The aim of this research was to define methods for early prediction (based on I. milk control record) of lactation flow in Holstein heifers as well as to choose optimal one in terms of prediction fit and application simplicity. Total of 304,569 daily yield records automatically recorded on a 1,136 first lactation Holstein cows, from March 2003 till August 2008., were included in analysis. According to the test date, calving date, the age at first calving, lactation stage when I. milk control occurred and to the average milk yield in first 25th, T1 (and 25th-45th, T2) lactation days, measuring monthcalving month-age-production-time-period subgroups were formed. The parameters of analysed nonlinear and linear methods were estimated for each defined subgroup. As models evaluation measures,adjusted coefficient of determination, and average and standard deviation of error were used. Considering obtained results, in terms of total variance explanation (R2 adj), the nonlinear Wood’s method showed superiority above the linear ones (Wilmink’s, Ali-Schaeffer’s and Guo-Swalve’s method) in both time-period subgroups (T1 - 97.5 % of explained variability; T2 - 98.1 % of explained variability). Regarding the evaluation measures based on prediction error amount (eavg±eSD), the lowest average error of daily milk yield prediction (less than 0.005 kg/day), as well as of lactation milk yield prediction (less than 50 kg/lactation (T1 time-period subgroup) and less than 30 kg/lactation (T2 time-period subgroup)); were determined when Wood’s nonlinear prediction method were applied. Obtained results indicate that estimated Wood’s regression parameters could be used in routine work for early prediction of Holstein heifer’s lactation flow.
ANALYSIS OF THE RELATIONSHIP BETWEEN FIRST THREE LACTATIONS OF HOLSTEIN COWS
Vesna Gantner,Sonja Jovanovac,Kre?imir Kuterovac
Poljoprivreda (Osijek) , 2005,
Abstract: The objective of this study was to evaluate relationship between milk yield in the first three lactations regarding levels of milk yield in the first lactation and levels of age at the first calving. Prediction of milk yield in later lactation based on milk yield in the earlier one was also carried out. The data used in this study were 5743 lactation yields collected from 1995 to 2003. All cows finished the first three lactations. Mean value of milk yield in the first lactation was 5283.5 kg, 6033.5 kg in the second and 6338.4 kg the third one. The milk yield estimation coefficients between the first and second lactation was 1.164, between the first and third was 1.231, and 1.079 between the second and third. The levels of milk yield in the first lactation highly significant influenced the value of estimation coefficient between first three lactations, while the age at first calving influenced less significantly. Determination coefficient (R2) values for models used in prediction ranged from 0.348 to 0.396.
Test-day records as a tool for subclinical ketosis detection
Gantner Vesna,Poto?nik K.,Jovanovac Sonja
Acta Veterinaria , 2009, DOI: 10.2298/avb0903185g
Abstract: The prevalence, as well as the effect of subclinical ketosis on daily milk yield, was observed using 1.299,630 test-day records collected from January 2000 to December 2005 on 73,255 Slovenian Holstein cows. Subclinical ketosis was indicated by the fat to protein ratio (F/P ratio) higher than 1.5 in cows that yielded between 33 to 50 kg of milk per day (Eicher, 2004). The ketosis index was defined in relation to the timing of subclinical ketosis detection to the subsequent measures of test-day milk yields. The effect of subclinical ketosis on test day milk yields were studied separately for each parity using the mixed model analysis. The statistical model included the fixed effect of ketosis index, calving year-month, lactation stage and random effect of animals included in the study. The prevalence peak of subclinical ketosis occurred in the first month of lactation. Subclinical ketosis had a significant negative effect on daily milk yield. Decrease in milk yield in the amount of 4.21 kg/day; 2.73 kg/day; 2.78 kg/day; 2.83 kg/day; and 3.72 kg/day in each parity were determined within 35 days after the detection of subclinical ketosis. The decrease continued in subsequent milk controls. The research results show that test-day records could be a useful tool for early detection of subclinical ketosis.
The lifetime production of Bovec and Improved Bovec sheep breeds
Gregor Gorjanc,Vesna Gantner,Dragomir Kompan
Mljekarstvo , 2009,
Abstract: Production data of Bovec and Improved (with East-Friesian) Bovec sheep born between years 1989 and 2006 were used for the analysis of culling dynamics and lifetime production. Lifetime production was calculated as the sum of production at each lambing (number of born and liveborn lambs and litter birth weight), weaning (number of weaned lambs and litter weaning weight) or during each lactation (milk yield, fat (6.5 %) and protein (5.8 %) corrected milk yield (FPC; Pulina et al., 2005.), and fat and protein yield) for culled sheep. Animals with any missing records from the first till the last lambing, weaning or lactation were removed from the analysis. Animals that left the system of animal recording alive, due to selling or the cancellation of recording by a breeder were also excluded. Dataset included records for 2254 sheep: 1734 of Bovec and 520 of Improved Bovec breed. Data preparation and statistical analysis were performed with the use of a statistical program R (R Development Core Team, 2007.) and additional packages Zelig (Imai et al., 2007; Bailey and Alimadhi, 2007; Imai et al., 2008) and lme4 (Bates and DebRoy, 2004; Bates, 2007). Results have shown that in the period ≤1996 Bovec breed had on average 4.4 lactations in their lifetime, which was almost one lactation more than in Improved Bovec breed. In the period after the year 1996 the highest proportion of animals were culled in the first lactation (as expected due to culling dynamics), with slightly higher proportion in Improved Bovec breed than in Bovec breed. Lifetime number of born, liveborn and weaned lambs was higher for about one lamb in Improved Bovec breed. Lifetime lamb weight gain did not differ between breeds, due to the high frequency of early weaning in Improved Bovec breed. During lifetime, Improved Bovec sheep produced around 200 kg (~34 %) more milk, around 190 kg (~32 %) more FPC milk, around 12 kg (~32 %) more milk fat, and around 10 kg (~34 %) more milk protein than Bovec breed. However, if the mean metabolic weight of breeds is taken into account the difference in milk production amounts to only ~6 % (~2 % for FPC milk). These results show that Bovec breed has satisfactory milk production, but too low body weight for intensive milk production. On the other hand, low body weight makes this breed suitable for extensive farming in hill and mountain areas. Improved Bovec breed has good results in Slovenian conditions, due to the similarity of environmental conditions with East Friesian’s country of origin.
Mare’s milk: composition and protein fraction in comparison with different milk species
Klemen Poto?nik,Vesna Gantner,Kre?imir Kuterovac,Angela Cividini
Mljekarstvo , 2011,
Abstract: The usage of the mare’s milk as functional food especial for children intolerant to cow’s milk, with neurodermitis, allergies and similar disorders desiring to improve the quality of life is fiercely debated for last decades but there were no scientific studies to suggest such use of mare’s milk based on scientific research. The objectives of this study were to determine similarities of mare’s milk in comparison with milk of ruminants (cattle, sheep and goat) and human milk in terms of milk composition and protein fraction as whey proteins, caseins and micelles size. All differences were discussed regarding usage of mare’s milk in human diet and compared to milk which is usually used in human nutrition. Regarding composition, the mare’s milk is similar to human milk in of crude protein, salt and lactose content, but it has significantly lower content of fat. Fractions of main proteins are similar between human and mare’s milk, except nitrogen casein (casein N) which has twice lower content in human than in mare’s milk. Content of casein N from all ruminants’ milk differ much more. Just for true whey N and non-protein nitrogen (NPN) similar content as human and mare’s milk has also goat milk. The casein content is the lowest in human milk; this content is three times greater in mare’s milk and six to seven times greater in goat’s and cow’s milk, while in sheep’s milk it is more than 10 times grater. In many components and fractions mare’s milk is more similar to human milk than milk of ruminants. A detail comparison of protein fraction shows quite large differences between milk of different species. More study and clinical research are needed that can recommend usage of mare’s milk in human diet as functional food on scientific bases.
Effect of milk recording scheme on lactation milk yields prediction accuracy
Vesna Gantner,Sonja Jovanovac,Nikola Ragu?,Drago Soli?
Mljekarstvo , 2009,
Abstract: Different AT milk recording schemes, with purpose of detection of scheme with the highest lactation milk yields prediction accuracy as well as with simplest practice application, were compared in this study. Analysed data were collected from November 2004 till November 2006 on 15 family farms in Croatia according to A4 milk recording scheme by the field assistants of the Croatian Livestock Centre. Measuring at test-day included measurement of milk yield and taking one sample for milk composition analysis at each milking (evening and morning). During research, total of 769 cows were included in research. More than 50 % of all cows were Holstein breed (58.9 %), while the rest of the cows belonged to the Simmental breed. For prediction of daily milk yields two methods were used: M I. = linear regression of daily on partial values with taking into account the interval between successive milkings; M II. = doubling of partial values. The Test Interval Method (TIM) was used for prediction of lactation values. As evaluation criteria for comparison of schemes, correlation and difference between estimated and true milk yields were used. Scheme S II., that is use of first morning, then evening test-day record, in case of doubling the partial yields, showed as scheme with the highest prediction accuracy. Regardless of milk recording scheme, use of method M I. in daily milk yields prediction, resulted in high accuracy and low milk yields, milk fat and protein bias prediction in standard lactation. Research results implicate the use of method M I. in daily milk yields prediction, as well as possibility of different AT milk recording schemes combination in practice.
Temperature-humidity index values and their significance on the daily production of dairy cattle
Vesna Gantner,Pero Miji?,Kre?imir Kuterovac,Drago Soli?
Mljekarstvo , 2011,
Abstract: The objectives of this study were to determine the microclimatic conditions in stables in three climactic regions (East, Mediterranean, and Central) of Croatia as well as to evaluate the effect of temperature-humidity index (THI) values on the daily production of dairy cattle. With that purpose, 1675686 test-day records collected from January 2005 until April 2010 were extracted from HPA (Croatian Agricultural Agency) database. For estimation of the effect of THI on daily production of dairy cows fixed-effect model that took into account the effects of lactation stage, breed, calving season, measuring season, and THI group (T1 - THI≤72; T2 - THI>72) was used. Model was applied to each class of parity (P1, P2, P3, P4 and P5) and region. During the analysed period, the highest monthly averages of ambient temperature were determined in Mediterranean region, the highest monthly averages of relative humidity were observed in Central region, while the highest monthly mean values of temperature-humidity index (THI) were determined in Mediterranean region. Heat stress conditions indicated with mean daily values of THI>72 were determined during spring and summer season in all analysed regions. Absence of heat stress conditions during autumn and winter season also characterised all three regions. Highly significant (P<0.01) decrease of daily milk yield as well as of daily fat and protein content due to enhanced THI was observed in all cows regardless the parity class and in all three climatic regions. Furthermore, the most deteriorate effect of heat stress was observed in East region. During heat stress period, with the aim of minimization of the effects of heat stress, it is necessary to regulate management strategies in the dairy herd.
Methods for estimation of daily and lactation milk yields from alternative milk recording scheme in Holstein and Simmental cattle breeds
Vesna Gantner,Sonja Jovanovac,Marija Klop?i?,Martino Cassandro
Italian Journal of Animal Science , 2010, DOI: 10.4081/ijas.2009.519
Abstract: The aim of this study was to compare different statistical methods for the estimation of daily and 305-day lactation milk, fat and protein yields of Holstein and Simmental cattle breeds using an alternative milk recording scheme. Data included 6,824 individual test-day milk yield records collected according to the A4 milk recording method on 668 cows reared on 15 family farms. Daily milk, fat and protein yields were estimated using several statistical methods with regard to breed. The 305-day lactation yields were calculated from estimated daily yields using the Test Interval Method. The correlation between estimated and true yields, as well as the mean difference among estimated and true yield were used as the evaluation criteria for estimation methods. The linear regression of daily to partial milk, fat and protein yields while taking into account the interval between successive milkings was shown to be the most accurate model for estimating daily values, either from morning or evening records. The simple doubling of morning or evening records overestimated and underestimated the daily yields, respectively. When 305-day lactation milk, fat and protein yields were compared no difference between evaluated methods were found. Also, a separate estimation of daily and 305-day lactation yields according to breeds did not result in increased estimation accuracy.
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