Slaughtered Cattle as a Source of Rumen Fluid to Evaluate Supplements for In Vitro Degradation of Grass Nuts and Barley Straw

Abstract

This factorial study examined the potential of slaughtered cattle as a source of rumen fluid (RF) to test the impact of 0, 90, 180 g/kg forage (Amount) of 2 supplements (Low protein of 12% =LP; high protein of 25% =HP) on in vitro rumen degradation of grass nuts (Grass) and barley straw (Straw) over various times. RF was collected from three slaughtered cattle (Animal) on three separate occasions and buffered under CO 2 as inoculum at 39 o C. About 1g ground Straw or Grass and each amount of LP or HP were mixed in separate test tubes with 50 ml inoculum under CO 2 . The tubes fitted with Bunsen valves were incubated at 0-72h after which the contents were washed and dried to estimate dry matter disappearance (DMD). The DMD were statistically analysed for the main effects of Animal, Forage, Supplement, Amount and their interactions at each incubation but not Animal based interactions. The Forage, Amount and Animal effects were significant (P<0.01) at most incubations whereas Supplement effect was significant at 72h only showing greater DMD for HP than LP (P<0.05). DMD increased with time for all main effects. Grass had greater DMD than Straw at all incubations (P<0.001). DMD increased (P<0.05) with time but not at 0h with increasing Amount and increased DMD was greater from 0 to 90 g/kg than at 90 to 180 g/kg. The animals differed (P<0.05) at all but 0h showing variable responses with the confounding effect of their gender, age, breed, size and pre-slaughter feeding. Apparently slaughtered cattle can be used to obtain RF to evaluate supplements for in vitro forage degradation. However, the selection of suitable donor animals of similar pre-slaughter characteristics would be critical if in vitro studies involving slaughtered animals are to be used to evaluate feed supplements before their use for grazing ruminants.

Fresh or frozen rumen contents from slaughtered cattle to estimatein vitro degradation of two contrasting feeds

“…In fact the degradation of grass nuts in this study was similar to the earlier data for a different sample of the same batch of grass nuts (Chaudhry, 2008). The greater DM and CP degradation for the fresh than the thawed inocula at some or most hours indicated that the freezing followed by thawing did affect the feed degrading ability of rumen microbes in the thawed inocula.…”

“…The rumen degradation data for different feeds are traditionally obtained by using surgically modified animals for either in sacco studies or to obtain rumen fluid for in vitro studies (Chaudhry, 2007(Chaudhry, , 2008; Mohamed and Chaudhry, 2008;Chaudhry and Mohamed, 2011). Due to high management and welfare costs of maintaining rumen fistulated animals, the availability of such rumen fluid to commercial laboratories on regular basis is restricted.…”

“…However, it would be beneficial if rumen contents are preserved in sufficient quantities for their later use as a source of microbial inoculum when there is a need to estimate degradation of different ruminant feeds. Although slaughtered cattle may be used as an alternative source to obtain rumen fluid, obtaining rumen fluid from slaughtered animals needs transport, man-hours, and time adjustment between researchers and abattoirs (Chaudhry, 2008). Therefore, it would help if the rumen fluid of slaughtered animals could be preserved in sufficient quantity for its subsequent incubation with various feeds to estimate their in vitro degradation on a regular basis.…”

Effects of dietary supplementation of spices on forage degradability, ruminal fermentation, in vivo digestibility, growth performance and nitrogen balance in Black Bengal goat

“…The higher content of CP, ether extract (data not shown) in black cumin and maximum level of CP in cumin might have increased IVD of rice straw. Supplements having higher CP and ether extract can be useful to complement the nutritive value of LQF as suggested by Chaudhry (2008). The higher amount of soluble sugars of turmeric (Khan & Chaudhry, 2010) than other spices increased the IVD initially at 24 hr, but when the sugars were utilized by the microbes IVD was levelled off at 48 hr.…”

Methods to study degradation of ruminant feeds

“…However, keeping fistulated animals for obtaining rumen fluid is unacceptable on animal welfare grounds. Therefore, either rumen fluid from freshly slaughtered animals or fresh or thawed faeces could be used as alternative sources of microbes instead of rumen fluid from fistulated animals for the in vitro incubation of feeds to estimate rumen degradation (Chaudhry ( 109 , 110 ) ). However, it would be essential to standardise the protocols for each method ( in sacco and alternatives).…”