2. Rumen development
Morteza nemati

3. Feed concentrates have been formulated for calves to maximize not only DMI and ADG, but also VFA production Ruminal fermentation of dietary concentrates and their end products (especially butyrate and propionate) play a central role in ruminal epithelium differentiation and papilla development

4. increasing ruminal propionate production by feeding a high-concentrate diet may be associated with improved animal performance and rumen development via its indirect effect on endocrine hormones

5. The five requirements for ruminal development are • Establishment of bacteria. • Liquid. • Outflow of material (muscular action). • Absorptive ability of the tissue. • Substrate to allow bacterial growth, such as recycled minerals, as well as feed nutrients.

6. The rumen is incompletely developed both physically and metabolically at birth (Warner et al., 1956)
Increased sodium and chloride transport by the developing rumen epithelium could reflect an increase in the SCFA absorptive capacity
by the rumen epithelium (Sehested et al., 1999)

7. The rumen develops from a very small organ in newborn calves (1–2 L) into the most important part of the gut (25–30 L) by 3 months of age
The rumen’s capacity and the intake of solid feed are closely related
Rumen development is very slow in calves fed large quantities of milk

10. Solid feeds and rumination both stimulate saliva production and this supplies nutrients such as urea and sodium bicarbonate to produce the substrates for bacterial growth
Urea supplies nitrogen for the microbes
sodium bicarbonate acts as a rumen buffer when calves eat large quantities of cereal grains later in life as the rumen microbes can produce a lot of lactic acid during fermentation

11. overloading butyrate and propionate may promote keratinization of papillae by increasing the mitogenic rate and decreasing the apoptosis rate of the epithelium Because of the lower digestibility of forage in the rumen of calves, the VFA produced are insufficient for optimal growth of papillae and thus, rumen development is slowed

12. Forage has the potential to encourage early rumination and enhance rumen pH and rumen muscle strength, while also reducing cancerous proliferation and keratinization of rumen papilla Large amounts of forage in the feed leads to decreased DMI and ADG in calves

13. at weaning, the production of the ketone body β-hydroxybutyrate (BHBA) from butyrate by rumen epithelial cells increases sixfold

14. Ruminal absorptive capacity is affected by rumen pH and the gradient of VFA concentration between the ruminal lumen and epithelial cells. The blood VFA absorption is a function of rumen surface area, which is highly dependent on the number and size of its papillae. The rumen epithelium itself utilizes VFA for its energy needs, their availability for whole-body metabolism depends on the extent of their use by the ruminal epithelia.

16. Size of Ruminant Stomach Compartments
Adult, %
Newborn, %
Rumen 55 29
Reticulum 7 6
Omasum 24 14
Abomasum 51

17. alfalfa hay and sodiumpropionate in calf starter diets

18. The differences in forage source, quantity, and particle size might have influenced the differences in ADG and final BW

21. Biranvand , 2014

27. in the case of illness, feeding plans need to be adjusted because physiological development is slowed during illness
Higher milk rations can decrease solid feed intake before weaning, decreasing feed intake and growth in days after weaning
large particle size and bulk of fibrous feed can provide mechanical stimuli to enhance rumen weight, its physical capacity, and volume in calves

28. Similar concentrations of blood BHBA (an indicator of metabolic function of the rumen wall) in calves fed hay or no hay indicates that the rumen walls were equally efficient in converting butyrate to BHBA

29. Hepatic SCFA metabolism
Th liver and ruminal epithelium have diffrent affities towards individual SCFA
Th low rumen epithelial affity but high liver affity for propionate ensures that the largest propionate metabolism occurs in the liver

30. Butyrate is removed substantially by the ruminal epithelium prior to reaching the liver a large portion of acetate released by the ruminant liver originates from peroxisomal β-oxidation

32. Grain processing
Previous studies indicated that grain processing level influenced rumen VFA production, rumen pH, and rumen NH3
Murphy et al. (1994) reported increased total VFA concentrations and decreased ruminal pH when whole corn ( WC) was replaced with DRC in all-concentrate diets
grain processing had less influence on total VFA production and rumen pH when forages were incorporated into the ration

33. Heat processing of grains has been shown to increase ruminal propionate production
Ruminal butyrate production appears to be enhanced by physical processing
Some researchers have indicated that increased grain processing lowers rumen NH3 however, this is not always the case

34. GRAIN PROCESSING
the SFC ration had more fine particles that may have become trapped by rumen papillae or were less effective in removing dying epithelial cells, subsequently resulting in keratin buildup and rumen mucosa thickening

35. rumen pH was greatest in WC calves throughout the study, differences between processing methods were inconsistent

37. Crocker et al. (1998) reported decreasing rumen NH3 concentration as SFC replaced DRC, attributing this effect to increased microbial use of available NH3. In addition, others have reported a tendency for decreasing rumen NH3 concentrations as starch degradability increased Rumen NH3 concentrations observed in the current study fluctuated drastically across all treatments and do not indicate.

38. Any definite effect of heat processing or mechanical processing on rumen NH3 concentrations. Rumen NH3 concentrations did appear to decrease as starter intake increased, indicating ruminal microbial proliferation and increased incorporation of NH3 nitrogen into microbial protein

41. Calves Fed Milk Through Step-Down and Conventional Methods

44. Addition of sodium butyrate (SB) in MR stimulated pancreatic secretion and intestinal cell proliferation villus growth , and brush border and pancreatic enzyme activity, which resulted in improved digestibility and better performance and health of calves (Hill et al.,
2007)

45. Although liquid feed in the preruminant calf bypasses the reticulorumen via the reticular groove it might also affect rumen development indirectly. Liquid feed determines the growth and health of animals and thus, solid feed intake and consequently, rumen development (Khan et al., 2007)

46. Gorka et al , 2011

47. Castells et al, 2013
The inclusion of chopped forage in the diet of young calves leads to a better rumen environment because rumen pH increases and the expression of MCT1 transporter tends to increase
fractional rate of passage in the rumen:
oat hay > alfalfa hay

50. The results reported in the present study suggest 2 possible mechanisms that could be involved in the changes observed in rumen fermentation parameters when forage is included in the diet of young calves. First, differences in rumen epithelia gene expression could explain the lower rumen VFA concentration in forage-fed calves. Animals fed forage tended to show increased expression of MCT1 in the ruminal wall. This transporter is located in the basolateral membrane of the rumen epithelium and it is involved in the transport of lactate, acetate, and protons from the rumen epithelium into the bloodstream

51. it could be speculated that due to the enhanced proton export, intracellular pH probably increased, and it may have heightened absorption of short-chain fatty acids (SCFA) from ruminal lumen into epithelium both by simple diffusion of protonated SCFA and by SCFA−/ HCO3− exchange. Despite the observed differences in NHE1 protein expression between AH and OH animals, overall expression of this gene was low, and thus the role of this protein in thecontrol of intracellular pH homeostasis might not be very relevant.

54. Effects of dietary carbohydrates