Effects of Two Different Energy Sources in Total Mixed Diets on the Performances and Blood Metabolites of Lactating Boerka Goats

Abstract

Lactating goats are prone to negative energy status due to increased body fat reserve mobilization to support the high energy requirement of milk production. The study was aimed to investigate the responses of the lactating goat on diets provided in total-mixed ration differing in the energy sources. The experiment was conducted using a total of 35 does having 2-3 parities and an average bodyweight of 30.3±4.48 kg and BCS of 2.5 ± 0.05 on a scale basis of 1 to 5. Animals were allocated to one of five dietary treatments (seven animals/treatment) formulated to be iso-nitrogen dan iso-calory in a total mixed ration. Cassava meal was used as the source of glucogenic energy and bergafat as the main source of lipogenic energy. There were no DM intake differences (P>0.05) between the glucogenic diet (1.49% and 2.28% fat), but significant increases (P<0.05) in DM intake were observed in goats fed lipogenic diets (fat content range from 4.7 to 7.5%). All animals gained during the lactation period with ADG ranged from 15 to 46 g, indicating that all experimental animals were in positive energy balances. Goat receiving more glucogenic diets gained least and having higher FCR compared to those receiving lipogenic diet (P<0.05). Body condition scores were also improved in lactating goat received more lipogenic diets. Blood glucose and blood urea concentration was not affected by diet treatments and lactation period (P>0.05) and ranged from 37 to 43 mg/dl and 39 to 51 mg/dl, respectively. Numerically, however, the blood glucose and urea level linearly increased as the diet becoming more lipogenic due to the increased feed intake. It is concluded that lactating goats offered diets with lipogenic energy sources (7.5% fat content) presented in pelleted total mixed-ration during the entire lactation period had a higher dry matter and nutrient intakes, body weight gain and body condition score compared to those fed diets with glucogenic energy source.