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Monthly and seasonal variations among dietary, blood and milk parameters and their interrelationships were investigated during the lactation period in Holstein dairy cows in order to determine reliable dietary indices that could be useful in the studies related to milk yield improvement. Samples were prepared monthly, up to 11 months of lactation and were analyzed by the current laboratory methods using appropriate kits. Mean monthly and seasonal comparison of the dietary, blood and milk values were different among sampling times (p

Lipids in liver wet and dry matter, liver moist and dry matter and their relationships were investigated based on species, sex and age in cows, buffaloes, sheep and goats. Mean percentage of lipids in liver wet and dry matter and liver dry matter in cows were 3.60%, 1.10%, 29.70%, and for buffaloes were 5.30%, 1.55%, 29.20%, sheep 3.00%, 0.83%, 27.90%, and goats 2.910%, 1.55% and 28.40%, respectively. The highest and lowest percentage of lipids in liver wet and dry matter was observed in buffaloes and sheep, and for the liver dry matter was recorded in cows and sheep, respectively. Analyses showed significant differences in liver parameters among ruminants (p < 0.01). Gender, except for goats, did not affect the animals' liver parameters. In overall 15.00% of buffaloes and 3.50% of cows showed over 10.00% lipids in liver, while none of small ruminants appeared to have over 6.00% lipids in liver. There was no correlation between liver lipid and liver dry matter. In conclusion mean percentage of lipid in liver dry matter in small ruminants was less than large ruminants. Liver dry matter was high in cows and low in sheep. Mean differences in liver parameters was significant, while the age and sex of the animals were not. Liver lipidosis in buffaloes seems greater than in cows, and in small ruminants it was negligible. No correlation was expected between liver parameters. Finally, on the basis of liver dry matter, the liver in ruminants ranked from cows to buffaloes, goats and sheep.

Daily variations in milk urea, protein and lactose concentrations and their interrelationships were investigated in 36 and 40 moderate and high milk producer cows, respectively. Milk samples were collected from the morning and afternoon milking yield for up to one week from Holstein dairy cows in Urmia, Iran. The overall mean milk urea nitrogen (MUN), milk protein and lactose concentrations were 19.7 mg/dL, 3.6 g/dL and 4.13 g/dL, respectively. Daily mean concentrations for the milk parameters revealed the highest concentrations for MUN and milk protein in the afternoon and morning milking, respectively. Milk lactose was constant for both milking yields. Significant differences (p