Browsing by Author "Nayeri, Amir"

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Effect of the ratio of zinc amino acid complex to zinc sulfate on the performance of Holstein cows
(Elsevier, 2014-07) Nayeri, Amir; Upah, Nathan C.; Sanz-Fernandez, M. Victoria; DeFrain, Jeffery M.; Gorden, Patrick J.; Baumgard, Lance H.; Sucu, Ekin; Uludağ Üniversitesi/Ziraat Fakültesi/Zootekni Bölümü.; 0000-0003-1470-2751; AAG-8331-2021; 14038064900
Multiparous (n = 70) and primiparous (n = 66) Holstein cows were balanced by 305-d previous mature-equivalent milk yield and parity and assigned to 1 of 3 dietary treatments to evaluate the ratio of zinc sulfate to zinc amino acid complex (CZ) in pre- and postpartum Holstein cows fed diets containing 75 mg of added zinc/kg. Treatments were (1) 75 mg of supplemental zinc/kg of dry matter (DM) provided entirely as zinc sulfate (0-CZ); (2) 0-CZ diet, except 33.3 mg of zinc sulfate/kg of DM in the prepartum and 15.5 mg of zinc sulfate/kg of DM in the postpartum diet were replaced by CZ from Availa-Zn (16-CZ; Zinpro Corp., Eden Prairie MN); and (3) 0-CZ diet, except 66.6 mg of zinc sulfate/kg of DM in the prepartum and 40.0 mg of zinc sulfate/kg of DM in the postpartum diet was replaced by Availa-Zn (40-CZ). Cows were housed at the Iowa State University Dairy Farm and were individually offered a total mixed ration containing dietary treatments beginning at 28 +/- 15 d before expected calving date until 250 d in milk. Relative to 0-CZ, multiparous cows (but not primiparous) fed CZ (16-CZ or 40-CZ) had increased (20%) colostrum IgG concentrations. Prepartum DM intake (DMI) was decreased with CZ supplementation. Postpartum DMI was decreased in cows fed CZ, whereas milk yield (MY) was increased in the 40-CZ-fed cows relative to those fed both 0-CZ and 16-CZ. Feed efficiency increased linearly when measured as MY/DMI, 3.5% fat-corrected MY/DMI, and solids-corrected MY/DMI. Regardless of level, feeding CZ decreased services per conception. Feeding 16-CZ decreased milk fat concentration and feeding CZ linearly increased milk urea nitrogen concentration. In summary, supplementing zinc as a mixture of CZ and zinc sulfate, as opposed to supplementing only zinc sulfate, has beneficial effects on production parameters in dairy cows, with those benefits becoming more apparent as the ratio of CZ to zinc sulfate increases.
The effects of supplemental protease enzymes on production variables in lactating Holstein cows
(Taylor & Francis Ltd, 2014-03-07) Nayeri, Amir; Sanz-Fernandez, M. Victoria; Upah, Nathan C.; Baumgard, Lance H.; Sucu, Ekin; Uludağ Üniversitesi/Veteriner Fakültesi/Zootekni Anabilim Dalı.; 0000-0003-1470-2751; AAG-8331-2021; 14038064900
A study was conducted to examine the effects of supplemental dietary protease enzymes on production variables in dairy cattle. Ninety-six multiparous lactating Holstein cows (624 +/- 62 kg body weight and 154 +/- 104 days in milk) were blocked according to parity, days in milk, and previous milk production and randomly assigned to a control total mix ration (TMR) or a TMR containing a blend of supplemental protease enzymes (PE; 4 g/cow/d) in a crossover design with two 21-day experimental periods. Daily pen milk yield and dry matter intake (DMI) were recorded and milk composition from all cows was determined on d 15, 17. 19 and 21 of each period. There was no treatment effect on milk yield (37.6 kg/d), but supplemental PE-fed cows consumed less DMI (P<0.05) compared to controls and therefore tended to have improved feed efficiency (P=0.06). Feeding supplemental PE decreased blood urea nitrogen (P<0.05) compared to the control cows. However, feeding PE had no effect on milk fat and protein content but tended (P=0.08) to increase milk lactose concentration and tended (P=0.10) to decrease milk urea nitrogen levels and somatic cell score. Results indicate that supplemental PE may enhance production efficiency and improve parameters of nitrogen status.
Prolactin's role during acute and chronic heat stress in growing pigs
(Wiley, 2012-04) Sanz-Fernandez, Maria Victoria; Pearce, Sarah C.; Upah, Nathan C.; Long, Liu-Rong; Nayeri, Amir; Gabler, Nicolas K.; Patience, John F.; Hsu, Walter H.; Rhoads, Robert P.; Baumgard, Lance Hall; Sucu, Ekin; Uludağ Üniversitesi/Ziraat Fakültesi.; 0000-0003-1470-2751; AAG-8331-2021