BODY CONDITION SCORE AND REPRODUCTIVE PERFORMANCE OF DAIRY COWS IN EASTERN REGION OF PARAGUAY CONDICIÓN CORPORAL (CC) Y DESEMPEÑO REPRODUCTIVO EN VACAS LECHERAS DE LA REGIÓN ORIENTAL DEL PARAGUAY

. The objective of the current investigation work was to compare body condition score (BCS) to reproductive performance in milking dairy cows in Paraguay. We used 1169 dairy cows of 13 farms from October 2013 to August 2015. Data were analyzed using SAS Enterprise Guide version 4.3. BCS in early and mid lactation period were lower than in the late period (p < 0.05), although it had large variation. In addition, daily milk yields of Holstein cows were higher than cows mixed with various breed (p < 0.01); however, BCS between two breeds was mostly similar. In addition, we compared BCS between cows on farm with the calving interval less than 365 days (n = 243, good reproduction) and other cows (n = 710) except 6 farms without reproductive record. In cows with good reproductive performance, calving interval (p < 0.0001) and days open (p < 0.0001) were shorter and daily milk yield was lower (p < 0.0001) than cow of other farms. During the all lactation period, BCS of cows with good reproductive performance were higher than others (p < 0.05). In addition, BCS of cows with good reproductive performance did not decrease after calving, whereas BCS of cows on other farms decreased during early and peak lactation period compared with dry period (p < 0.05). Moreover, BCS did not differ between cows with higher and lower milk yield. In conclusion, the results under the running conditions of the experiment indicate that BCS affect reproductive performance of Holstein and crossbreed milking cows in eastern region of Paraguay. Our data suggests that controlling the decrease of BCS after calving for milk production may improve the reproductive performance.


INTRODUCTION
intake and milk production (2). However, information of BCS in Paraguay is little, so suitable score for management leading to good reproductive In Paraguay, dairy sector has grown in recent performance is not clear. Therefore, the present years owing to genetic improvement of dairy cattle study examined the BCS of dairy cows and compared and enhanced infrastructure, and milk production the BCS between cows on farm with higher has steadily increased from 122 million of liters in reproductive performance and cows on farm with 1996 to 450 million of liters in 2010 (1). However, lower reproductive performance in the eastern optimal nutritional management of dairy cattle has region of Paraguay. not yet been well established in Paraguay, especially in the east region of the country. Some of the reasons are that the amount and kind of feed is not stable MATERIALS AND METHODS throughout the year and grazing method is different from farm to farm despite dairy farm production One thousand one hundred sixty-nine dairy depended on forage. In addition, there is little data cows from 13 dairy farms in the eastern region of for the chemical composition in grass varieties, Paraguay (Alto Paraná Department and Itapúa silage and prepared concentrates of each farm. Department) were used for this study. Two types of Therefore, although feed management depending on dairy cattle breed are mainly found in Paraguay. One the policy in each farm, it is important to manage type of breed with strong Holstein characteristics while understanding the nutritional status of cow in and the other type include cattle of mixed breed order to keep a certain level of milk production and including beef cattle. BCS of former is assessed using reproductive performance. a 1 to 5 scale with 0.25 intervals according to Ferguson et al. (1994). However, it is difficult to Measurement of feed intake is one of the evaluate in the same way for cattle of mixed breeds, most suitable variables to reflect nutritional status; because the skeleton related to BCS measurement however, monitoring of feed intake in individual such as the transverse processes is different cows is impractical for most commercial dairy farms.
between Holstein and mixed breed. Therefore, we Evaluation of energy and metabolic status based on modified the method of BCS measurement for metabolic hormones and metabolites in the blood is Holstein (Figure 1-1 and 1-2 A), which has been suitable and useful, but blood sampling and shown by Ferguson et al. 1994 (2), in order to laboratory analyses are limited because of higher applicate for cattle of mixed breeds (Figure 1-1 and technology and cost. On the other hand, body 1-2 B). Based on these methods of BCS condition score (BCS) is one of the useful tool that is measurement, BCS were assessed 1 to 8 times for feasible for commercial dairy farms. BCS is the each herd between October 2013 and August 2015 assessment of body fat store and related to feed (Table 1).
ISSN 2226-1761 Data of daily milk yield at the month when regarded as 0 to 50 days in early, 51 to 110 days in BCS was measured were collected from 7 farms peak, 111 to 220 days in mid and 221 to 300 days in except 6 farms without record, and reproductive late lactation period, respectively. In addition, dry records such as calving date and insemination date period was regarded as 60 days before calving. Data in each cow were collected from all farms (Table 1).
were analyzed by the Student's t-test, Wilcoxon signed-rank test or Bonferroni correction after statistical testing of normality using the In addition, we regarded cows on farm with Kolmogorov-Smirnov test (SAS Enterprise Guide the calving interval less than 365 days as good version 4.3, SAS Institute Inc.; Cary, NC, USA). Results reproductive performance, and compared BCS in are reported as mean ± standard error of the mean each lactation period between cows on farm with (SEM); differences with p < 0.05 were considered higher reproductive performance and cows on other significant. farms with lower reproductive performance. Postpartum days of each lactation period were 18 ISSN 2226-1761 Kawashima C. y col.

RESULTS AND DISCUSSION
peak lactation period (Holstein; 3.21, mixed breed; 3.26, P<0.05) and BCS of other lactation period did not differ between the two types of breed. Figure 2 shows the distribution of BCS (n = 1169) and daily milk yield (n = 389) in all cows. Daily milk yield was declined over time after calving, Table 2 shows the average of BCS, daily milk although its variation was large. Averages of daily yield and reproductive performance in cows on farm milk yields in each lactation period, expressed in with good reproductive performance and cows on liters, were 17.3 in early, 15.5 in peak, 14.2 in mid and other farms with low reproductive performance. 11.5 in late lactation period, respectively. Daily milk There was no difference of breed between the two yield in early was higher than in mid (p < 0.05) and farms. It was reasonable that calving interval (p < late (p < 0.05), and it in peak was greater than in late 0.0001) and days open (p < 0.0001) were shorter in (p < 0.05). On the other hand, BCS had large variation, cows with good reproductive performance than cow and the average of BCS in each period was 3.48 in dry, of farms with lower reproductive performance. 3.22 in early, 3.24 in peak, 3.40 in mid and 3.45 in late, However, BCS was higher (p < 0.0001) and daily milk respectively. Although BCS in early and mid lactation yield was lower (p < 0.0001) in cows with good period were lower than other period (p < 0.05), the reproductive performance than cow of other farms, change of BCS after calving was smaller compared although postpartum days at BCS measurement were with previous reports (3,4,5). It is considered that similar between two farms. Figure 5 shows the one of the reasons is lower milk yield in cows of the comparison of BCS in each lactation period and dry present study than in cows of the previous studies period between cows on farm with good reproductive mentioned recently. Moreover, distribution of BCS performance and cows on other farms. During the all and daily milk yield of Holstein cows (BCS, n = 995; lactation period, BCS of cows with good reproductive daily milk yield, n = 348) and mixed breed cows (BCS, performance were higher than cows of other farms (p n = 144; daily milk yield, n = 38) are shown in Figure 3 < 0.05 in early, p < 0.01 in peak and late, and p < 0.001 and 4, respectively. Daily milk yields of Holstein cows in mid). In addition, BCS of cows with good were higher in early (18.1 L vs. 13.1 L, p < 0.01), peak reproductive performance did not decrease after (16.1 L vs. 11.7 L, p < 0.0001) and mid (14.6 L vs. 9.8 L, calving, whereas BCS of cows on other farms p < 0.001) than cows mixed with various breed; decreased during early and peak lactation period however, BCS between two breeds differed only in compared with dry period (p < 0.05).   Almost dairy cows undergo a period of Peña and Naranjito, and dairy farmers for their negative energy balance (NEB) during the early support. This study was supported by Japan postpartum period, because the energy required for International Cooperation Agency (JICA) (Project milk production and maintenance of tissue function name; Mejoramiento de la Lechería en la Zona Este exceeds the energy uptake during this period (6,7). Granelera del Paraguay). Although dairy cows in Paraguay may not have severe NEB because of lower milk production, the REFERENCES energy intake for milk production and maintenance of tissue function might be insufficient in cows on 1.Servin B, Vásquez F. Study on inclusive development in Paraguay. Santiago de Chile: United Nations. Chapter ; other farms. In addition, the result of comparing BCS 2013. 170-174. between cows with the average of daily milk yield during the lactation period more than 15 L (n = 232) 2.Ferguson JD, Galligan DT, Thomsen N. Principal and less than 15 L (n = 286) was that BCS did not descriptors of body condition score in Holstein cows. J Dairy Sci. 1994;77: 2695-2703 differ between cows with higher milk yield and lower milk yield in this study (3.16 vs. 3.15