Feed intake, feeding behavior, growth performance, nutrient digestibility, and carcass characteristics of goats fed pelleted total mixed rations with varying Rhodes hay levels

Abstract

The study aimed to evaluate the effects of dietary physical form and Rhodes grass hay inclusion level on growth, feeding behavior, digestibility coefficient, and carcass characteristics in fattening male goats. The experimental factors were dietary physical form (mash and pellet) and the inclusion level of Rhodes grass (150 kg/t and 250 kg/t; RG150 and RG250). Their combination formed four treatments: RG150M (mash, 150 kg Rhodes grass and 850 kg concentrate per tonne), RG250M (mash, 250 kg Rhodes grass and 750 kg concentrate per tonne), RG150P (pellet, 150 kg Rhodes grass and 850 kg concentrate per tonne), and RG250P (pellet, 250 kg Rhodes grass and 750 kg concentrate per tonne). Forty male Beetal goats (20.3 ± 1.9 kg; mean ± SD) were randomly divided into four treatments (10 bucks/treatment). After adaptation for 10 d, the animals were measured for animal performance for 91 d and digestibility coefficients for 7 d and finally slaughtered for the determination of carcass characteristics. Dry matter intake (DMI) was higher (P < 0.05) in RG250P, and average daily gain (ADG) was highest (P < 0.05) in RG250P, followed by RG150P. Goats fed mash-formed diets spent more time (P < 0.05) consuming food than those fed pellet-formed diets. The feeding rate (g/min) was higher (P < 0.05) in pelleted diets than in the mash form, and meal size (g/meal) was higher (P < 0.05) in those goats fed 150 kg/t Rhodes grass-based total mixed ration (TMR). The rumination time was higher (P < 0.05) in the mash and RG250 groups as compared to pelleted and RG150 groups. Laying time (min/d) and laying frequency were higher (P < 0.05) for goats fed TMR in pelleted than mash form. The digestibility of nutrients was higher (P < 0.05) in goats fed mash-formed TMR than those fed pelleted TMR. Nitrogen balance was not (P > 0.05) influenced by the form of the diet or hay inclusion level. The hot carcass weight and chilled carcass weight were higher (P < 0.05) in goats fed pelleted TMR than those fed the mash-formed TMR. It can be concluded that the feeding pelleted total mixed ration increases DMI, ADG, resting period, and hot carcass weight. When Rhodes grass hay is included in the pelleted diet at 250 kg/t, DMI and ADG were highest. The inclusion level of Rhodes grass at 250 kg/t also has higher rumination time, meal frequency, and drinking frequency.