EFFECT OF COBALT SUPPLEMENTATION ON GAS PRODUCTION MEASUREMENTS, ESTIMATED ENERGY VALUES AND MICROBIAL PROTEIN, IN VITRO

M.E.A. Nasser, A.M. Ismail

Abstract
In vitro gas production techniques simulate the rumen fermentation process and they have been used to evaluate the potential of feeds to supply nutrients to ruminants. Thus, effects of various levels of cobalt supplementation on gas production and rumen fermentation were investigated using an in vitro gas production technique. Ground samples (100 mg DM) of 70% wheat straw and 30% concentrate were incubated in 50 ml glass syringes with rumen fluid obtained from fistulated sheep fed berseem hay and commercial concentrate mixture twice a day. Cobalt (Co) was added at 0.00, 0.35, 0,70 and 1.0 mg/kg DM of feed. Cumulative gas production was recorded at 3, 6, 9, 12, 24, 48, 72 and 96 h of incubation and the kinetics of gas production was described by using the equation Gas(t)= a + b (1- e-ct)). At 24 h, the gas production volume was highest for sample with the third level of cobalt (0.70 mg/ kg DM) (P<0.05) and greater for second and fourth levels of Co (0.35 and 1.0 mg/kg DM, respectively) (P<0.05) than sample without Co (control). Total gas production at 96 h and the maximum rate of gas production increased when Co was added to samples. Also, the results showed that there were significant differences (p<0.05) in metabolizable energy (ME) and net energy (NE), dry matter digestibility (DMD), organic matter digestibility (OMD), Short chain fatty acids (SCFA) and microbial protein. In an overall conclusion it seems that, the cobalt addition improved the rumen fermentation.

Key words: Wheat straw, gas production, digestibility, energy value, microbial protein, sheep

EFECTELE SUPLIMENTĂRII CU COBALT ASUPRA MĂSURĂTORII PRODUCŢIEI DE GAZ, VALORILOR ESTIMATE ALE ENERGIEI ŞI PROTEINEI MICROBIENE, IN VITRO

M.E.A. Nasser, A.M. Ismail

Rezumat
Tehnicile de producere a gazului in-vitro simuleaza procesul fermentativ ruminal si sunt utilizate pentru a evalua potentialul nutreturilor de a asigura animalelor rumegatoare nutrientii necesari. Astfel, efectele diferitelor niveluri de cobalt adaugat în hrana asupra productiei de gaz si proceselor fermentative ruminale au fost investigate prin tehnica producerii de gaz in-vitro. Probe de substrat (100 mg SU), alcatuit din 70% paie de grâu si 30% concentrate au fost incubate în seringi de sticla de 50 ml, umplute cu fluid ruminal provenit de la oi fistulate, hranite în prealabil cu fân de trifoi egiptean si amestec standard de concentrate, de doua ori pe zi. Cobaltul (Co) a fost adaugat în doze de 0.00, 0.35, 0,70 si 1.0 mg/kg SU hrana. Productia cumulata de gaz a fost înregistrata dupa 3, 6, 9, 12, 24, 48, 72 si 96 ore de incubatie, iar cinetica productiei de gaz a fost descrisa prin utilizarea ecuatiei Gas(t)= a + b (1- e-ct). Dupa 24 ore, volumul productiei de gaz a fost cel mai mare în cazul probei cu al treilea nivel de includere pentru cobalt (0.70 mg/ kg SU) (P<0.05) si, de asemenea, mai mare pentru nivelurile 2 si 4 de includere (0.35 si 1.0 mg Co/kg SU) (P<0.05), comparativ cu probele fara adaos de cobalt (lot de control). Productia totala de gaz dupa 96 ore si randamentul de conversie au crescut atunci când s-a adaugat cobalt la probele investigate. S-au identificat, de asemenea, diferente semnificative (p<0.05) în privinta energiei metabolizabile (EM), a energiei nete (EN), a digestibilitatii substantei uscate (DSU) si a celei organice (DSO), a acizilor grasi cu lant scurt (AGLS) si a proteinei microbiene. Ca o concluzie de ansamblu, s-ar parea ca adaosul de cobalt în hrana îmbunatateste fermentatia ruminala.

Cuvinte cheie: paie grâu, productie de gaz, digestibilitate, valoare energetica, proteina microbiana, ovine