جستجوی مقالات مرتبط با کلیدواژه « _ تولید شیر » در نشریات گروه « کشاورزی »

The effect of different levels of alfalfa hay and corn silage, in early lactation diet, on milk production and on milk components in Holstein cows was investigated. Fifteen Holstein cows (37 ±10 DIM) were taken in a completely randomized design experiment, lasting for 9 weeks. Three levels of hay and corn silage namely: 1) 10% alfalfa -30% silage corn (Diet 1), 2) 20% alfalfa -20% silage corn (Diet 2) and 3) 30% alfalfa -10% silage corn (Diet 3) former the treatments. The ratio of forage to concentrate was taken as the same (40: 60) in all the treatments. Cows were fed in Total Mixed Rations (TMR) and twice daily. They were milked 3 times a day at 02:00, 10:00, and 18:00 h. Milk production was recorded at each milking, but milk composition was weekly determined. Dry matter intake for each cow was daily assessed. Dry matter intake was higher (P<0.05) when cows fed diet 2 (23.20 kg per day) as compared with diets 1 (22.95 kg per day) and 3 (18.64 kg per day). Treatments affected milk production (P=0.014). Substituting corn silage with alfalfa hay increased the percentage of milk fat (P<0.05), but did not affect milk protein (P>0.05). Apparent total tract digestibility of dry matter (DM), organic matter, crude protein and neutral detergent fiber did not significantly differ among different dietary treatments (P>0.05). Blood parameters were not seriously affected by dietary treatments (P>0.05), although glucose content for Diet 1 was higher than that for Diet 2.

Economic data and performance records from 10 Iranian Holstein dairy cattle herds, as well as milk production and fertility records from Iranian Center of Animal Breeding and Animal Production Improvment were used to estimate the effect of calving difficulty on milk production, fertility and as well on the economic aspects of maternal and direct calving difficulty. Calving difficulty could be divided into 3 classes. Class 1: normal calving; Class 2: calving that needed help by one man worker, and Class 3: calving with serious damage to calf and mother. Milk production decreased about 46 kg and 323 kg in classes 2, and 3 of the calving difficulty incidences, respectively. Calving difficulty caused decreases in fertility performance by 0.22 more inseminations to be performed in class 2 and 0.35 more ones in class 3. Stillbirth was not affected as by class 2 but was intensified in class 3 by 5 percent. Total economic loss attributed to classes 2 and 3 of calving difficulties were $57.76 and $243.83, respectively. Estimated economic value for maternal and direct effect were $37 per unit change in liability per cow/year. Following a correction of the economic values by cumulative discounted expressions, the economic values for maternal and direct effects amounted to $22.79 for direct, and $8.54 for maternal difficulties.

The effects of Monesin and propylene glycol on feed intake, milk production, and composition as well as some blood metabolites of 16 primiparous and multiparous Holstein lactating cows (60±30 Days In Milk (DIM), milk production of 33±3 Kg/day) were evaluated. Cows were experimentally in a arranged in a randomized complete block design of: 4 feeding treatments, and 2 blocks of either primiparous or multiparous. They were fed a balanced total mixed ration of 60% concentrate and 40% forages (with or without additives). Cows in group I were fed Total Ixed Ration (TMR) with no additives (control). Cows in group? were fed TMR with 335 mg/head/day Monensin. Cows in group? were fed TMR with 400 ml/head/day of propylene glycol, and finally cows in group IV were fed TMR with 335 mg/head/day of monensin and 400 ml/head/day of propylene glycol. Daily milk yield, milk composition and some blood metabolites were recorded. Data were analyzed using mixed models for repeated measurements. The experimental treatments did not affect either feed intake or milk composition, but propylene glycol caused significant increase in cow's milk yield (P<0.05). Monensin along with propylene glycol significantly increased concentrations of plasma glucose and insulin (P<0.05). Plasma triglyceride was lower in monensin with propylene glycol treated¬ cows (P<0.05). This treatment had not significantly affected the concentration of plasma calcium and phosphorus (P>0.05). Based upon the results of the present study propylene glycol can improve milk production of cows in their early lactation stage and monensin together with propylene glycol improves the concentration of glucose and insulin, in the plasma.