نشریه پژوهش در تغذیه دام
سال یکم شماره 1 (بهار و تابستان 1393)

This experiment was conducted to determine the nutritional requirement of digestible methionine (dMet) in growing Japanese quail from 8 to 28 d of age. A total of 540 seven-day-old quail chicks were allotted in 9 treatments including several levels of dMet (0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70 and 0.75% of diet) with 4 replicates and 15 birds in each based on a completely randomized design. A basal diet was formulated to meet all nutritional needs except dMet, and to create the experimental treatments incremental levels DL-Met was added to the basal diet at the expense of corn starch. Growth data for body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) were recorded weekly. The results showed that the highest BWG and FI were obtained with 0.5% of dMet (8-14, 8-21, and 8-28 d of age). The lowest FCR was obtained at the 0.5% of dMet from 8-14 and 8-28 d of age. No significant effect of dietary Met was observed on carcass attributes (thigh and breast) and digestive organs (liver and length of small intestine) during the study. Also, the effect of dietary Met was not significant on immune-system related organs including spleen and bursa of Fabricius. This study showed that 0.5% of dMet would be sufficient for optimum performance of growing Japanese quails.

To assess the effects of different kind of fat in transition period diets on plasma concentration and gene expression of PPARγ, 30 multiparous Holstein cows randomly attributed to 3 experimental diets containing palm oil (treatment 1), soybean oil (treatment 2) or roasted whole soybean (treatment 3). After 14 days adaptation to experimental stalls, the animals had free access to experimental diets during 3 weeks before to 3 weeks after calving. Blood samples were collected on day 14 postpartum for determination of PPARγ concentration. Subcutaneous adipose tissue was sampled on day 14 postpartum for determination of peroxisome proliferators-activated receptor gamma (PPARγ) gene expression. Obtained data were analyzed using completely randomized design. The results showed that on day 14 postpartum, the plasma levels of PPARγ as well as expression of PPARγ gene in adipose tissue were not affected by dietary treatments (P > 0.05).

The validity of simple method for detection and determining of proteases has been tested in this survey. In conventional method, protease activity is quantitated by direct measurement of substrate cleavage to amino acid product and concentration of amino acid has been measured by spectrophotometric assay. The simple method is qualitative procedure for determination of protease activity and it is based on degradation of milk protein in the milk agar gel. With measuring the clear zone around the wells on milk agar gel, it is possible to measure protease activity when compared to standard with known protease activity. The simple method has been tested for determining the protease activity on Kiwifruit as a source of plant protease and rumen fluid from adult lamb, ewe and dairy cows as a sources of microbial protease. Results showed positive and significant correlation (r=0.926; P=0.008) between conventional and simple methods for protease activity. Therefore, due to simplicity and rapidness of the simple method for detection of protease activity, this method can be suggested for farm level protease activity measurements.

Nowadays, the poultry industry has gained special importance due to higher demand for white meat than red meat. One of the main factors affecting body weight gain in broiler chickens is the nutritional requirements for essential amino acids including methionine, lysine, and threonine. In this survey, the growth rate of the birds in response to dietary levels of Met, Lys, and Thr were analyzed using response surface methodology (RSM) and artificial neural networks (ANN). The efficiency of these methods was assessed using some statistical parameters including coefficient of determination (R2), mean square error (MSE), mean absolute deviation (MAD), mean absolute percentage error (MAPE), and average absolute deviation (AAD). The higher R2 of ANN models (R2 = 0.92) than that of RSM models (R2 = 0.51) and lower residual distribution for ANN models revealed that ANN is the more efficient tools for recognition of birds responses to nutritional factors than regression method.

This study was performed using 12 multi parturient dairy cows in postpartum stage of early lactation period. Animals were assigned randomly to a 4×4 single Latin square crossover design. Treatments and periods were 4 and the length of each period was 21 days which records were collected at the end of week 3 of each period. Treatments were as as follow: control group (no niacin supplementation), 12 g, 14 g, and 16 g niacin supplementation. Daily milk records were collected and milk samples were analyzed every 15 days regularly. The results showed that niacin supplementation had a significant effect on milk yield (both raw yield and 3.5% and 4% FCM) (p<0.05). Row milk yield, 3.5% and 4% FCM milk yields were higher in 14 and 16 g niacin groups than 12 g niacin and control groups. Also niacin supplementation had a significant effect on milk compositions including milk protein, total solids and solid not fat percentages (p<0.05), but not on milk fat and lactose percentages. In conclusion, higher levels of niacin improved milk production and composition compared to lower levels. As a final result, 16 g niacin per day had the highest effect on the productive parameters in contrast to other treatments.

The objective of this study was to investigate the effects of prebiotic MHF-Y on productive performance and egg quality of laying hens. A total of 144 Lohmann LSL-Lite laying hens at 32 wk of age were allocated to 4 experimental treatments with 6 replicates per treatment and 6 hens per replicate. Hens were reared at standard conditions for 6 week and provided a standard basal diet (ME =2720 kcal/kg and CP=145 g/kg) with no additives as control and basal diet supplemented with 0.075, 0.15 or 0.225 % prebiotic MHF-Y. During the experimental period, productive performance for each treatment was recorded and at the end of trial, 18 eggs were also taken from each treatment for determination of egg quality parameters. The egg production, feed intake, egg mass and feed conversion ratio were not affected (P>0.05) by dietary prebiotic supplementation. However, egg weight was higher (P=0.04) in hens fed 0.15 % prebiotic diet compared to other experimental groups. Although, egg index, Haugh unit and yolk colour were also not affected (P>0.05) due to prebiotic supplementation, eggshell weight and thickness were higher (P<0.05) in hens fed 0.15 % prebiotic compared to other experimental groups.

In the present study the effects of dietary methionine restriction on body weight and femur, tibia and humorous growth were evaluated using 200 pieces of Japanese quail. Birds were fed by two diets including with methionine and without methionine supplement for 42 days. Individual body weights were measured at 7, 14, 21, 28, 35 and 42 days of age. In addition the bone characteristics were measured at 24 and 35 days of age. The results suggest that dietary methionine restriction caused significant decreases in body weight up to 35 days of age (P<0.05). In comparison with later ages, the body weight was decreased more at early ages. The bone growth was not affected by the dietary methionine restriction. The results also show that the body weight were not significantly different between males and females until 35 days of age. The Importance of methionine supplement for the growth traits measured at the different ages was not the same where the body weight was not affected significantly after five weeks of age.