Effect of Calving Interval on Milk Yield and Quality Evolution during Lactation in Dairy Cows

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1 Effect of Interval on Milk Yield and Quality Evolution during Lactation in Dairy Cows Simona Baul 1*, Ludovic-Toma Cziszter 1, Stelian Acatincai 1, Traian Cismas 1,2, Silvia Erina 1, Dinu Gavojdian 3, Iulian Tripon 1, Genoveva Buzamat 1 1 Faculty of Animal Science and Biotechnologies, Banat University of Agricultural Sciences and Veterinary Medicine, , Timisoara, Romania 2 Direction for Agriculture of Braila County, , Braila, Romania 3 Research and Development Station for Sheep and Goats of the Romanian Academy for Agricultural Sciences and Forestry, , Caransebes, Romania Abstract Researches were made on 125 lactations from Romanian Black Spotted cows, aimed at studying the evolution of the between calving on milk quantity and quality. Data were recorded and statistically analyzed by means of ANOVA / MANOVA determining the average values and dispersion indices. Based on averages parameters of lactation curves were calculated using the mathematical model proposed by Wood, called the incomplete gamma function. The between calving significantly influenced (p 0.05) lactation curve aspect for the percentage of dry defatted from milk for the daily growth rate (parameter c) between calving 351 to 450 days and of over 450 days ( ). Also we ve met significant differences (p 0.05) for the initial concentration of the percentage of total solids in milk for parameter a from the between calving up to 350 days and calving days ( ). Keywords: calving, dairy cows, milk yield, Romanian Black Spotted breed 1. Introduction The calving represents the time length between two successive calving, and influences the regularity of births, the number of calves produced by a cow and milk production per lactation and for the entire productive life [1]. is the reproduction index which gives the most accurate information regarding the quality of the reproduction in a farm of multiparous cows. influences calving rate, number of calves produced by a cow and milk yield produced in the entire productive life of an animal [2]. A calving which is rhythmic has a positive impact on milk yield [3]. * Corresponding author: Baul Simona, Tel , simonabaul@animalsci-tm.ro can be established in two ways: open days period + gestation period and/or lactation period + dry period. Due to the fact that gestation length is relatively invariable ( days), it can be concluded that the calving is influenced by the duration of the open day s period, lactation and dry off periods [4]. The aim of the current study was to evaluate the effects that calving has on lactation curve shape for total milk yield and milk quality (non-fat total solids and dry matter). 2. Materials and methods Researches were made in the Didactical Farm of the Banat s University of Agricultural Sciences and Veterinary Medicine Timisoara, on 125 lactations from Romanian Black Spotted cows. 289

2 Data were recorded and statistically analyzed by means of ANOVA / MANOVA determining the average values and dispersion indices. Based on averages parameters of lactation curves were calculated using the mathematical model proposed by Wood, called the incomplete gamma function [5]. 3. Results and discussion In Table 1 are being presented average values and dispersion indices for incomplete gamma function parameters of the daily normal milk yield during normal lactation depending on the calving in cows Romanian Black and White Spotted cows. The amount of milk in the first day of control (parameter a) was the lowest in cows that had the calving between lower than 350 days (14.04 kg). Highest initial milk quantity was registered by cows which had a calving between days (16.84) kg milk. In cows with calving s over 450 days the milk yield began to decrease. Milk yield daily growth rate (parameter b) was highest (0.067 kg) in cows with the calving lower than 350 days. The more the calving was higher the day rate of milk yield increase was lower. Daily drop rate of milk production (parameter c) was the lowest in cows that had between calving higher than 450 days ( kg). The highest rate of decrease in the quantity of daily milk after reaching peak lactation curve was obtained from cows with the calving lower than 350 days ( kg). From initial levels, lactation curves for the two classes of calving s (up to 350 days and between 350 and 450 days) had a relatively similar appearance (parameters b and c in Table 1 are about the same in these two classes). Table 2 presents the means and dispersion indices for incomplete gamma function parameters where the percentage of total solids during the normal lactation, depending on the calving in Romanian Black and White Spotted studied cows. The percentage of total solids in milk on the first day of control (parameter a) had smaller values and closer to the calving between of days (12.89%) and the one over 450 days (12.98%), while one up to 350 days total solids percentage value was a maximum of 13.70%. Daily decrease rate of the percentage of total solids in milk (parameter b) had the highest value in cows group with calving s for up to 350 days (-0.015%). The lowest value of this parameter is obtained from cows that had calving between 351 and 450 days (-0.011%). Daily decrease rate of the percentage of total solids in milk (parameter c) was the lowest in cows that had calving s of over 450 days ( %), increasing to a value of % in cows with calving s of up to 350 days. The biggest daily decline rate percentage of total solids was obtained from cows that had calving s between days ( %). In Table 3 are being presented average values and dispersion indices for incomplete gamma function parameters for the percentage of total solids of normal lactation day depending on the calving in Romanian Black and White Spotted cows. The percentage of total solids in milk on the first day of control (parameter a) was smaller and registered values close to the calving days (12.89%) and the one higher than 450 days (12.98%), while for the calving of up to 350 days the total solids percentage value was at the maximum of 13.70%. Daily rate of decrease in the percentage of total solids in milk (parameter b) had the highest value in cows with calving s of up to 350 days ( %). Extending the calving from 12 to 15 months did not cause any significant production losses, however extending calving to 18 months resulted in a significant decrease in daily milk yield [6]. The lowest value of this parameter was obtained from cows that had calving s between 351 and 450 days (-0.011%). Daily rate of decrease in the percentage of total solids in milk (parameter c) was the lowest in cows that were in the calving of over 450 days ( %), increasing to a value of % in cows with calving s of up to 350 days. The biggest daily percentage decline rate of total solids was obtained from cows that had calving s ranging between days ( %). Results are in accordance with those reported by Butler et al. (2010) which stated that lactations with a 24 months calving may be a viable alternative to culling non-pregnant cows and be economically more suited to higher producing cows [7]. 290

3 Furthermore, Kolver et al. (2010) states that milking cows for 2 years consecutively, with calving and mating occurring every second year, may exploit the superior lactation persistency of high-yielding cows while improving reproductive performance [8]. Table 4 presents the differences and statistical significance for the development of incomplete gamma function parameters of milk and milk chemical components during lactation according to the calving in Romanian Black and White Spotted cows studied. In the table it can be seen that there were significant differences (p <0.05) for percentage of total non-fat solids daily growth rate (parameter c), the percentage of total non-fat solids between calving s ranging from 351 to 450 days and ones over 450 days ( ). For the daily percentage evolution in total dry matter, significant (p <0.05) differences were registered for the parameter a, the initial percentage of total solids between the calving s of up to 350 days and 351 to 450 days ( ). Table 1. Averages and dispersion indices for the incomplete gamma equation parameters for the daily milk production (kg) on normal lactation based on calving of the Romanian Black and White cows ± ± ± ± ± ± ± ± ± Table 2. Averages and dispersion indices for the incomplete gamma equation parameters for the daily solids non-fat percent on normal lactation based on calving of the Romanian Black and White cows ± ± ± ± ± ± ± ± ± Table 3. Averages and dispersion indices for the incomplete gamma equation parameters for the daily total dry matter percent on normal lactation based on calving of the Romanian Black and White cows ± ± ± ± ± ± ± ± ± Table 4. Differences and their significance for the incomplete gamma equation parameters for daily evolution of milk quantity and chemical components during lactation based on calving Trait Parameter Over a ns ns smaller than 350 b ns ns c ns ns Total non-fat solids (%) Total dry matter (%) smaller than a ns - b ns - c * - a ns * b ns ns c ns ns a ns - b ns - c ns - 291

4 kg milk Figure 1. Milk quantity evolution during normal lactation based on calving of the Romanian Black and White cows breed non-fat solids Figure 2. Total solids non-fat percent evolution during normal lactation based on calving of the Romanian Black and White cows breed dry matter Figure 3. Total dry matter percent evolution during normal lactation based on calving of the Romanian Black and White cows breed 292

5 Differences of the parameters of incomplete gamma function between the three classes of calving s led to different aspects of the lactation curve (Figure 1). Thus, the between two successive births of over 450 days of lactation, the curve was flatter than the other two classes. In Figure 2 can be seen the evolution of lactation curve for total non-fat solids percentage per normal lactation, based on the calving s in Romanian Black and White Spotted breed cows. The sharpest lactation curve was obtained from the calving s of days, where initially the total non-fat solids was 8.48% and then decreased to 8.38% at 41 days after calving and then increased gradually to a value of 8.55% at the end of lactation. The flattened shape of the lactation curve was observed in calving s over 450 days, the initial value was 8.71% for the non-fat total solids, which reached a low of 8.67% at 54 days of lactation and then increased again reaching a value of 8.71% at the end of lactation. In Figure 3 it can be seen that there were differences between the three groups of calving s for the lactation curve aspect. Thus, the calving up to 350 days and at between 351 and 450 days of lactation, the curves had a similar aspect, except that the first class percentage of total solids in milk was higher, resulting throughout lactation a percentage of total solids greater than the second class. A flatter curve for the percentage of total solids in milk was recorded at a calving higher than 450 days. Change in percentage of total solids at this time was very low during lactation. Thus the initial total solids percentage was 12.98%, decreased to only 12.82% at 52 days after birth, towards the end of lactation the percentage of total solids to reach 12.99%. 4. Conclusions The calving has significantly (p 0.05) influenced shape of the lactation curves for total un-fat solids content, when the calving ranged between days and s higher than 450 days. Evolution of the daily percentage of total dry matter registered significant (p<0.05) differences between the calving s smaller that 350 days and s of days. References 1. Cziszter, L.T., Dirijarea functiei glandei mamare, Ed. Eurostampa, 2003, pp Melendez, P., Pinedo, P., The association between reproductive performance and milk yield in Chilean Holstein cattle, Journal of Dairy Science, 2007, 90(1), Pacala, N., Corin, N., Biologia reproducerii animalelor, Îndrumător de lucrări practice, Ed. Agroprint, 2002, pp Acatincai, S., Tehnologia cresterii bovinelor, Ed. Agroprint, 2010, pp Wood, P.D.P., Algebraic Model of the Lactation Curve in Cattle, Nature, 1967, 51(11), Koc, A., Effects of some environmental factors and extended calving on milk yield of Red Holstein cows, Spanish Journal of Agricultural Research, 2012, 10 (3), doi: /sjar/ Butler, S.T., Shalloo, L., Murphy, J.J., Extended lactations in a seasonal-calving pastoral system of production to modulate the effects of reproductive failure, Journal of Dairy Science, 2010, 93 (3), Kolver, E.S., Roche, J.R., Burke, C.R., Kay, J.K., Aspin, P.W., Extending lactation in pasture-based dairy cows: I. Genotype and diet effect on milk and reproduction, 2007, Journal of Dairy Science, 90(12),