HamidReza Dadkhah; GholmReza Ghorbani; Farzad Hashemzadeh; Abbas Rajaeerad
Volume 25, Issue 1 , April 2023, , Pages 13-24
Abstract
The objective of this study was to evaluate the effect of feeding two oral Ca boluses at calving and 12 h later on feed intake, milk yield, body weight (BW) changes, blood calcium and some reproductive parameters of high producing dairy cows during summer season. Twenty-four Holstein cows with average ...
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The objective of this study was to evaluate the effect of feeding two oral Ca boluses at calving and 12 h later on feed intake, milk yield, body weight (BW) changes, blood calcium and some reproductive parameters of high producing dairy cows during summer season. Twenty-four Holstein cows with average parity of 2.8 ± 0.8 were selected and randomly assigned to one of two treatments including control or the group receiving slow-release oral Ca bolus at calving and 12 h post-calving. Row milk yield was greater in cows receiving Ca boluses compared to control treatments during 21 days of lactation (P = 0.02). The milk fat (P = 0.01) and solid non-fat percentage (P = 0.05) were greater in cows that received calcium bolus compared to control treatment. In addition, energy-corrected and fat-corrected milk yields increased in cows received Ca bolus (P = 0.03). Plasma glucose and serum calcium concentration as well as BW change were not affected by experimental treatments. The pregnancy per artificial insemination, days to first insemination and open days were not significantly different between the experimental treatments (P >0.05). The results showed that using oral calcium bolus at calving and 12 hours after calving improved milk production and composition, but had no effect on serum Ca, BW change during first 21 days of lactation, and reproduction parameters.
Fateme Ahamadi; hamid Amanlou; Najme Eslamian Farsuni; Tahere Amirabadi Farahani
Volume 23, Issue 3 , September 2021, , Pages 363-374
Abstract
The objective of this study was to investigate the effect of decreasing dietary protein content with supplementing protected methionine (pMet) and lysine (pLys) on intake, milk yield, metabolic status, and apparent digestibility of nutrients in Holstein fresh cows. Immediately after calving, 16 cows ...
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The objective of this study was to investigate the effect of decreasing dietary protein content with supplementing protected methionine (pMet) and lysine (pLys) on intake, milk yield, metabolic status, and apparent digestibility of nutrients in Holstein fresh cows. Immediately after calving, 16 cows with the similar BCS and parity were randomly assigned to two treatments. Experimental diets provided equal amounts of lysine (132 to 133 g/d) and methionine (40 to 43 g/d). The treatments were: a diet containing 18.35 % CP without supplementing pMet and pLys (HP); and a diet containing 16.45 % CP with supplementing rumen-protected amino acids (LPML). Individual dry matter intake and milk yield were recorded daily during fresh period. Blood samples were collected at 0, 3, 7, 14 and 21 d after calving to determine the serum concentrations of mineral and metabolites. Feed intake was not affected by experimental diets but milk yield was higher for HP cows than cows in LPML (P < 0.01). The yield of milk protein, lactose, fat and concentration of milk urea nitrogen (MUN) were higher in HP cows compared to LPML (P < 0.05). Compared to HP cows, cows in LPML had lower blood urea nitrogen (BUN) and higher serum concentrations of total protein and globulin (P < 0.01). Based on the results of the present study, reducing dietary protein content while maintaining the supply of limiting amino acids decreased lactational performance and feed efficiency of Holstein fresh cows.
Mir Hossein Najafi; saeed zeinoaldini; Abolfazl Zali; mahdi Ganjkhanlou; Hossein Mohammadi
Volume 23, Issue 1 , March 2021, , Pages 73-82
Abstract
This study was conducted to investigate the effect of reducing dietary ratio of omega-6/omega-3 essential fatty acid (EFA) on dry matter intake, yield and milk composition, ovarian performance and blood concentrations of estradiol and progesterone using 24 multiparous Holstein cows. Experimental treatments ...
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This study was conducted to investigate the effect of reducing dietary ratio of omega-6/omega-3 essential fatty acid (EFA) on dry matter intake, yield and milk composition, ovarian performance and blood concentrations of estradiol and progesterone using 24 multiparous Holstein cows. Experimental treatments including different n-6 to n-3 EFA ratio; namely, 2.5, 4.5, or 6.5 parts of n-6 to 1 part of n-3 EFA. Dry matter intake and milk yield of cows were recorded daily. Also, body condition score and milk composition were recorded and ovarian activity was monitored by transrectal ultrasound scanning. Dry matter intake and milk composition were not affected by treatments. Daily milk yield was significantly higher in low and medium n- 6/n-3 FA ratio diets in comparison to high diet (P<0.05). Cows assigned to high n-6/n-3 FA ratio diet had greater plasma Haptoglobin concentrations compared to other diets (P<0.05). Results indicated that number of large follicles was greater in medium diet than high diet (P<0.05). Progestrone concentration was significantly decrease in high diet treatment (P<0.05). Results of this study indicate that modulating dietary n-6/n-3 FA ratio could lead to a higher milk yield and improve ovarian performance in fresh cows.