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Papers by Aleksandra Ivetic

Research paper thumbnail of Analyses of feeding behavior of dairy cows

Research paper thumbnail of Applying of Video Recording and Sequential Analysis Method in Investigation of Feeding Behavior of High Pregnant Heifers

Research paper thumbnail of The effect of corn grain micronization on diet digestibility and blood biochemical parameters in weaned Holstein calves

Spanish Journal of Agricultural Research, Jan 24, 2023

Aim of study: To evaluate corn grain micronization for calves fed a grower diet. Area of study: P... more Aim of study: To evaluate corn grain micronization for calves fed a grower diet. Area of study: Padinska Skela-Belgrade, Serbia. Material and methods: Thirty weaned Holstein dairy calves (65-74 days of age) were randomly assigned to one of two treatments with growers containing micronized (MCG) or untreated corn grain (UCG). The experimental period lasted for 60 days. Main results: The values of total tract apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP), and nonfiber carbohydrates (NFC) were higher for calves fed MCG versus those within the UCG treatment by 3.9% (p<0.05), 7.0% (p<0.01), 7.1% (p<0.01) and 7.5% (p<0.05), respectively, for the days 25-30 of the experimental period. In addition, the values of digestibility of OM, CP, and NFC were higher by 4.9% (p<0.05), 5.7% (p<0.05), and 6.0% (p<0.05), respectively, for the days 55-60 of the experimental period. The density of metabolizable energy, net energy for maintenance and gain in consumed dietary DM was higher (p<0.001) by 4.7, 5.5, and 7.2%, respectively for calves fed on the grower containing micronized corn grain (MCG), during the first digestibility period, and by 3.0, 3.6, and 4.6%, respectively, during the second digestibility period. Energy intake was lower (p<0.05) during the second digestibility period, for calves fed a diet with micronized corn. Blood urea N was affected (p<0.001) by dietary treatments. Lower values (10.2%) were observed for calves fed the grower containing MCG. Research highlights: The micronization of corn grain is a useful tool for optimizing weaned calf production due to the improvement in the digestibility and energy content of the ration.

Research paper thumbnail of Effects of different levels of physically effective fibers in diets for cows in early lactation

Spanish Journal of Agricultural Research, 2012

The study was conducted to investigate the effects of a total mixed ration (TMR) particle size on... more The study was conducted to investigate the effects of a total mixed ration (TMR) particle size on digestibility and production performances of the high-yielding cows in early lactation. The treatments were TMRs with forage-toconcentrate ratio 43:57 in diet dry matter, with four different mean particle lengths and physically effective fiber (PENDF) content based on different cut length of corn silage and alfalfa haylage. Determined values of PEF (physical effectiveness factor) and PENDF (through original and modified Penn State Particle Separator, PSPS) were considerably higher for forages and TMRs using the modified PSPS. The cut length of forage and particle size of TMRs did not affect dry matter intake. However reduced forage cut length significantly increased the apparent total tract digestibility of NDF (from 53.9 to 58.66%), and crude protein (from 71.56 to 77.90%), with the decrease in the non-fiber carbohydrate digestibility (from 91.99 to 86.80%). The increase in the milk yield (35.62 vs. 38.36 kg), and decrease in the milk fat (3.50 vs. 3.10%) and protein content (3.11 vs. 2.99%) were observed with the reduction of particle size in forages. There was no effect on milk fat daily yield, but the increase of the milk protein yield (1.08 vs. 1.15 kg) was determined with the reduced forage cut lengths. The milk fat to protein ratio had tendency to decrease with the reduced forage cut length. Decrease in forage particle size improved feed conversion ratio for milk production, improved digestibility and the milk yield, whereas milk protein content was reduced.

Research paper thumbnail of Effect of physical effectiveness on digestibility of ration for cows in early lactation

Journal of Animal Physiology and Animal Nutrition, 2013

A study was conducted to investigate the effects of a diet particle size on nutrient digestibilit... more A study was conducted to investigate the effects of a diet particle size on nutrient digestibility in cows in early lactation. Treatments were diets with forage to concentrate ratio 43:57% in diet dry matter, with four different physically effective fibres (peNDF) content based on different cut length of corn silage and alfalfa haylage. The physical effectiveness factors (pef) and peNDF content of TMRs (total mixed ration) were determined using Penn State Particle Separator (PSPS) with two (pef 8.0 , peNDF 8.0) or three (pef 1.18 , peNDF 1.18) sieves. The reducing of cut length of forages and particle size of diets did not affect on dry matter intake, while decreased peNDF intake by 16.34 and 8.83%, for peNDF 8.0 and peNDF 1.18 respectively. Apparent total tract digestibility of the nutrients was measured using two indicators: acid insoluble ash (AIA) and acid detergent insoluble lignin (ADL). Decreasing of forages cut length significantly increased apparent total tract digestibility of neutral detergent fibre (NDF) from 48.39% to 53.

Research paper thumbnail of Effects of forages and total mixed rations particle size on physical effectiveness and chewing activity of lactating cows

Biotechnology in Animal Husbandry, 2011

In study are determined effects of four different mean lengths of corn silage, alfalfa haylage an... more In study are determined effects of four different mean lengths of corn silage, alfalfa haylage and total mixed ration (TMR) for lactating cows on physical effectiveness (pef), physically effective fiber content (peNDF) and total chewing activity. High correlations were found between mean particle length of forages and TMR and their physical effectiveness in lactating cows nutrition as also with physically effective fiber content. Significant effect of ration particle size on stimulating total chewing activity of lactating cows was determined.

Research paper thumbnail of Analyses of feeding behavior of dairy cows

Research paper thumbnail of Applying of Video Recording and Sequential Analysis Method in Investigation of Feeding Behavior of High Pregnant Heifers

Research paper thumbnail of The effect of corn grain micronization on diet digestibility and blood biochemical parameters in weaned Holstein calves

Spanish Journal of Agricultural Research, Jan 24, 2023

Aim of study: To evaluate corn grain micronization for calves fed a grower diet. Area of study: P... more Aim of study: To evaluate corn grain micronization for calves fed a grower diet. Area of study: Padinska Skela-Belgrade, Serbia. Material and methods: Thirty weaned Holstein dairy calves (65-74 days of age) were randomly assigned to one of two treatments with growers containing micronized (MCG) or untreated corn grain (UCG). The experimental period lasted for 60 days. Main results: The values of total tract apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP), and nonfiber carbohydrates (NFC) were higher for calves fed MCG versus those within the UCG treatment by 3.9% (p<0.05), 7.0% (p<0.01), 7.1% (p<0.01) and 7.5% (p<0.05), respectively, for the days 25-30 of the experimental period. In addition, the values of digestibility of OM, CP, and NFC were higher by 4.9% (p<0.05), 5.7% (p<0.05), and 6.0% (p<0.05), respectively, for the days 55-60 of the experimental period. The density of metabolizable energy, net energy for maintenance and gain in consumed dietary DM was higher (p<0.001) by 4.7, 5.5, and 7.2%, respectively for calves fed on the grower containing micronized corn grain (MCG), during the first digestibility period, and by 3.0, 3.6, and 4.6%, respectively, during the second digestibility period. Energy intake was lower (p<0.05) during the second digestibility period, for calves fed a diet with micronized corn. Blood urea N was affected (p<0.001) by dietary treatments. Lower values (10.2%) were observed for calves fed the grower containing MCG. Research highlights: The micronization of corn grain is a useful tool for optimizing weaned calf production due to the improvement in the digestibility and energy content of the ration.

Research paper thumbnail of Effects of different levels of physically effective fibers in diets for cows in early lactation

Spanish Journal of Agricultural Research, 2012

The study was conducted to investigate the effects of a total mixed ration (TMR) particle size on... more The study was conducted to investigate the effects of a total mixed ration (TMR) particle size on digestibility and production performances of the high-yielding cows in early lactation. The treatments were TMRs with forage-toconcentrate ratio 43:57 in diet dry matter, with four different mean particle lengths and physically effective fiber (PENDF) content based on different cut length of corn silage and alfalfa haylage. Determined values of PEF (physical effectiveness factor) and PENDF (through original and modified Penn State Particle Separator, PSPS) were considerably higher for forages and TMRs using the modified PSPS. The cut length of forage and particle size of TMRs did not affect dry matter intake. However reduced forage cut length significantly increased the apparent total tract digestibility of NDF (from 53.9 to 58.66%), and crude protein (from 71.56 to 77.90%), with the decrease in the non-fiber carbohydrate digestibility (from 91.99 to 86.80%). The increase in the milk yield (35.62 vs. 38.36 kg), and decrease in the milk fat (3.50 vs. 3.10%) and protein content (3.11 vs. 2.99%) were observed with the reduction of particle size in forages. There was no effect on milk fat daily yield, but the increase of the milk protein yield (1.08 vs. 1.15 kg) was determined with the reduced forage cut lengths. The milk fat to protein ratio had tendency to decrease with the reduced forage cut length. Decrease in forage particle size improved feed conversion ratio for milk production, improved digestibility and the milk yield, whereas milk protein content was reduced.

Research paper thumbnail of Effect of physical effectiveness on digestibility of ration for cows in early lactation

Journal of Animal Physiology and Animal Nutrition, 2013

A study was conducted to investigate the effects of a diet particle size on nutrient digestibilit... more A study was conducted to investigate the effects of a diet particle size on nutrient digestibility in cows in early lactation. Treatments were diets with forage to concentrate ratio 43:57% in diet dry matter, with four different physically effective fibres (peNDF) content based on different cut length of corn silage and alfalfa haylage. The physical effectiveness factors (pef) and peNDF content of TMRs (total mixed ration) were determined using Penn State Particle Separator (PSPS) with two (pef 8.0 , peNDF 8.0) or three (pef 1.18 , peNDF 1.18) sieves. The reducing of cut length of forages and particle size of diets did not affect on dry matter intake, while decreased peNDF intake by 16.34 and 8.83%, for peNDF 8.0 and peNDF 1.18 respectively. Apparent total tract digestibility of the nutrients was measured using two indicators: acid insoluble ash (AIA) and acid detergent insoluble lignin (ADL). Decreasing of forages cut length significantly increased apparent total tract digestibility of neutral detergent fibre (NDF) from 48.39% to 53.

Research paper thumbnail of Effects of forages and total mixed rations particle size on physical effectiveness and chewing activity of lactating cows

Biotechnology in Animal Husbandry, 2011

In study are determined effects of four different mean lengths of corn silage, alfalfa haylage an... more In study are determined effects of four different mean lengths of corn silage, alfalfa haylage and total mixed ration (TMR) for lactating cows on physical effectiveness (pef), physically effective fiber content (peNDF) and total chewing activity. High correlations were found between mean particle length of forages and TMR and their physical effectiveness in lactating cows nutrition as also with physically effective fiber content. Significant effect of ration particle size on stimulating total chewing activity of lactating cows was determined.