Crude protein levels in diets containing pelleted concentrate for lactating goats: intake, digestibility, milk production and composition

Abstract

This study aimed to evaluate the effects of crude protein (100, 130, 160 and 190 g kg -1 of dry matter) of diets composed of 200 g kg -1 of Tifton 85 grass hay and 800 g kg -1 of pelleted concentrate on intake, nutrient digestibility, production and composition of milk in lactating goats. Eight female Saanen goats with 42.7 ± 1.43 kg and 57.7 ± 7.37 days of lactation and milk production of 2 ± 0.22 kg at the beginning of the experiment were housed in individual 1.32 × 3.10 m stalls and distributed into two 4 × 4-balanced Latin squares. Intake of dry matter, organic matter, crude protein, neutral detergent fiber corrected for ash and protein, ether extract and total digestible nutrients showed a quadratic effect, with maximum intake of 2.030; 2.000; 305; 769; 55 and 1.574 g day -1 at the levels of 140.7; 140.8; 189.2; 140.9; 144.9 e 142.7 g kg -1 DM, respectively. Digestibility of dry matter, organic matter, crude protein, non-fibrous carbohydrates, ether extract and total digestible nutrient level varied linearly, with increases estimated at 0.54; 0.50, 2.02, 0.49, 0.80 and 0.63 g/100g for each percentage unit of protein added to the diet, respectively. Milk production was affected, with increase of 0.54 g for each 1% crude protein added to the diet. Milk lactose level decreased linearly, unlike the fat level, which increased linearly. Protein level showed a quadratic behavior, with a maximum of 36.7 g per kg of milk at the level of 160.5 g per kg of DM. It is recommended to use crude protein between 135 g and 150 g per kg of dry matter of diets consisting of 800 g of pelleted concentrate (composed of soybean meal replacing the alfalfa hay as protein source) per kg of DM for lactating goats producing 2 kg of milk per day.

Crude protein levels in diets of lactating goats: nitrogen balance, urea excretion and microbial protein synthesis

“…Nitrogen intake followed the same trend as DM intake, whose maximum was with 140·7 g/kg CP in the diet (Santos et al . 2015). As for the N compounds in urine, excretion increased 2 g/day for every 10 g CP added to the diet.…”

“…This was probably because the offered diets presented a similar behaviour regarding the synchronization between protein and digestible energy, which contributed to the absence of effects of levels of CP on the microbial efficiency, where average TDN was 784 g/kg, although the intakes of DM and TDN varied quadratically (Santos et al . 2015).…”

Suplementación de caprinos con harina de vaina de mezquite en una pradera diferida de pasto (Urochloa mosambicensis) en la región semiárida

“…The use of mesquite pod meal (Prosopis juliflora (Sw.) D.C.) as a substitute for corn becomes an alternative due to its easy accessibility in semiarid regions and its use in diets for small ruminants has shown better productive indices compared to corn (8)(9)(10)(11)(12)(13) . However, the consumption of P. juliflora pods as the main source of food causes intoxication in animals (14)(15)(16) .…”