EFFECT OF THE KUDZU BANK OVER MILK PRODUCTION BASED ON Brachiaria decumbens DURING THE RAINING SEASON. GUALACA, PANAMA.

Abstract

Intending to evaluate the complementary effect of a Kudzu bank (Pueraria phaseoloides) over milk production based on Brachiaria decumbens, two studies were conducted at the Gualaca's Experimental Station. The experiments were analyzed using a double reversion design and two treatments (TR) were studied: grassing on B. decumbens (TSK) and grassing on B. decumbens plus restricted access to a Kudzu bank (TCK). The studies were performed during the rainning season, but in different years. Thirteen cross breeding cows (Holstein x Zebu) with a milk period average of 75 days were utilized for the first study. The grass was managed a rotational manner with 3 heads/ha, complete fertilization and rotation. The kudzu bank was grassed with 15 heads/ha, grassing continuously 1 hour daily after cows were milked in the morning and with a phosphoric fertilization. Each cow received 1.0 kg of molasses with 2% of urea ("as fed" basis) during the milk process in the morning and afternoon. For the second experiment the same plots of B. decumbens and Kudzu were used, but the grass was not fertilized and the animal units were reduced to 2.0 cows/ha.  In this study, 12 cattle (Holstein x Zebu) with a milk period average of 68 days were utilized. Results for the first study revealed that the dry matter availability (DMS), crude protein (CP) and the in vitro digestibility of the dry matter (IVDDM) for the grass were 2,476 kg/ha, 8.63% and 47.7%, and for the legume were 1,272 kg/ha, 20.42% and 44.71%, respectively. The average intake of Kudzu, determined by the cage technique, was 1.64 kg of DM/100 kg of body weight/day. Milk production was not affected by the Kudzu bank (P>0.824) and it was 9.4 lt/cow/d. Total solids and fat contents of the milk and body weight (BW) were also not affected by the bank (P>0.182) with means of 12.96%, 4.21% and 0.470 kg/cow/day, respectively. In the second study, grass averages for DMS, CP and IVDDM were 1,975 kg/ha, 4.93% and 43.77%, respectively and for the legume, 2,282 kg/ha, 17.17% and 43.2%, respectively. There was an important reduction of CP for the legume. Milk production resulted affected by the treatments (P>0.046) with means of 8.44 and 9.27 lt/cow/day for TSK and TCK, respectively. In contrast, body weight gain was not affected (P>0.787) with a mean of 0.177 kg/cow/day. The restricted utilization of the Kudzu bank just increased milk production when the legume had low CP (4-5%); therefore, it is concluded that its effect over milk production depends on the animal requirements of proteins and on the protein content of the legume.