• Asian-Australasian Journal of Animal Sciences
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• 제30권5호
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• pp.660-665
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• 2017

Objective: The objective of the study was to determine the effects of increasing levels of metabolizable protein (MP) on lactation performance and nitrogen (N) efficiencies in lactating dairy cows. Methods: Nine multiparous cows in mid lactation [$113{\pm}25$ days in milk] received three treatments in a $3{\times}3$ Latin square design with a period length of 21 days. The treatments were three diets, designed to provide similar energy and increasing supply of MP (g/d) (2,371 [low], 2,561 [medium], and 2,711 [high] with corresponding crude protein levels [%]) 15.2, 18.4, and 20.9, respectively. Results: Increasing MP supplies did not modify dry matter intake, however, it increased milk protein, fat, and lactose yield linearly. Similarly, fat corrected milk increased linearly (9.3%) due to an increase in both milk yield (5.2%) and milk fat content (7.8%). No effects were observed on milk protein and lactose contents across the treatments. Milk nitrogen efficiency (MNE) decreased from 0.26 to 0.20; whereas, the metabolic efficiency of MP decreased from 0.70 to 0.60 in low to high MP supplies, respectively. The concentration of blood urea nitrogen (BUN) increased linearly in response to increasing MP supplies. Conclusion: Increasing MP supplies resulted in increased milk protein yield; however, a higher BUN and low MNE indicated an efficient utilization of dietary protein at low MP supplies.

• 한국가축번식학회지
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• 제21권2호
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• pp.191-195
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• 1997

The objective of this study were to compare two methods of analysis of milk urea nitrogen (MUN) and to relate conentration of MUN to pregnancy rate in dairy cows. The Azotest and Sigma method for MUN analysis were compared. The Azotest consistently underestimated the Sigma values for same samples, except for those in rank 3. The CV for the Azotest, within each rank, were less than 15%, demonstrating acceptable repeatability of the Azotest within a rank. Concentrations of MUN higher or lower than MUN in rank 3 and 4 were associated with decreased pregnancy rate. Mun concentrations in rank 5 and 6 were associated with a, pp.oximately a 16 percentage point decrease in pregnancy rate. Mun concentrations in rank 5 and 6 were associated with a, pp.oximately a 16 percentage point decrease in pregnancy rate after AI in dairy cow. This results suggest that Azotest may be benificial to dairy producers to monitor urea nitrogen concentration in their herd in efforts to maintain or improve reproductive efficiency.

• Journal of Nutrition and Health
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• 제28권2호
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• pp.144-151
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• 1995

This study investigates the supplementing effects of milks by various heat treatment on growth performance and protein and calcium metabolism of rats. For 4 weeks, raw, LTLT-HTST-and UHT-processed milks were given to rats which fed on a calcium free, semi-synthetic diet containing 5%casein. There were no significant differences among the experimental groups in weight gain, feed efficiency ratio and the serum level of total protein and calcium. Also, no significant differences were showed in protein efficiency, nitrogen balance, apparent protein digestibiltiy and the contents of weight and calcium of the left femur as well as 2 incisors. However, the biological value of protein in the UHT-milk group was significantly higher than that of the raw-milk group. The apparent calcium digestibility and calcium balance in the UHT-milk group were higher than those in the raw-, LTLT- and HTST-milk groups. The weight of left femur in all the groups supplemented with various heat-treated milks was significantly impair the nutritive value of protein and calcium in milk. Futhermore, UHT-processing may improve the bioavailability of protein and calcium in milk.

• 한국미생물·생명공학회지
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• 제22권1호
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• pp.99-105
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• 1994

In this study we compared traditional cheesemaking process with the process utilizing ultrafiltration(UF) system. The whole milk retentates were prepared by ultrafiltration to volume concentration ratio(VCR) of 2.00:1, 2.25:1 and 2.50:1. Along with the untreated whole milk, there were studies in terms of the change of pH, titratable acidity and Soxhlet-Henkel($\circ $SH) value by mesophilic lactic starter and curd formation by rennet during Gouda cheese manufacture. Due to the increase of buffering effect titratable acidity and $\circ $SH value increased with the higher concentration ratio. When inoculated with the same volume of mesophilic lactic starter, less pH change occurred in UF retentates than in control milk. When added 0.0025% rennet, UF retentates coagulated 16~ 17 minutes ealier then the control milk. Gouda cheese yield from raw milk and UF retentates was 12.5~13.1% equally, but yield efficiency of UF retentate cheese was slightly higher than that of the raw milk cheese. Quantity of whey from retentate cheese was inversely related to VCR. But whey from retentate cheese contained higher percentage of amjor components than that from control milk cheese. In early ripening, the concentrations of lactose and soluble nitrogen compound were higher in retentate cheeses. Lactose content of control milk cheese was 3.49% and that of 2.00:1. 2.25:1, 2.50:1 VCR retentate was 3.77%, 4.89%, 7.03%, respectively. Thus, the more concentrated cheese contained a higher amount of lactose and all the lactose was hyerolyzed durion 35-day ripenion period. Soluble nitrogen compound of control milk cheese was 1.22% and that of UF cheeses was 1.82~2.06%. After 20-day ripening, soluble nitrogen compound increased starply in UF cheese.

• Food Science and Biotechnology
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• 제14권6호
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• pp.752-757
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• 2005

Changes in milk quality during storage of extended shelf life milk (ESL milk) and non-ESL milk were evaluated. No significant differences were observed between ESL and typical ultra high temperature-treated (UHT) milk in physicochemical properties including non-casein nitrogen (NCN) content, whey protein nitrogen index (WPNI), and L-ascorbic acid content. Low temperature and long time-treated milk (LTLT milk) had significantly higher NCN content and WPNI than those of UHT milk. In terms of microbial quality, yeast, molds, coliforms, and other bacteria were not detected in ESL milk during entire storage (21 days after expiration date) period at 4 and $25^{\circ}C$, while LTLT milk was more susceptible to microbial infection. Rats fed ESL milk resulted in significantly higher body weight, average daily gain, and feed efficiency than those given UHT milk. These results suggest ESL milk maintains better microbial quality than typical UHT milk, particularly during storage under extended refrigeration and at high temperature.

• Asian-Australasian Journal of Animal Sciences
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• 제33권2호
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• pp.236-244
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• 2020

Objective: The objective of this study was to evaluate the effects of different levels of quantitative feed restriction on nutrient intake and digestibility, nitrogen balance, efficiency and feeding behavior, and productive performance in F1 Holstein/Zebu cows during the middle third of their lactation. Methods: Sixty F1 Holstein/Zebu cows with 111.5±11.75 days of lactation and an initial body weight (BW) of 499±30 kg (mean±standard error of the mean) were used. The experimental design was completely randomized with the following diet levels of feed restriction: 3.39%, 2.75%, 2.50%, 2.25%, and 2.00% of BW, with 12 replications for each level. The experiment lasted for 63 days, of which each period lasted 21 days with the first 16 days for diet adaptation followed by 5 days for collection of data and samples. Results: For each 1% of BW diet restriction, there was a decrease in dry matter intake of 5.26 kg/d (p<0.01). There was no difference in daily milk production (p = 0.09) under the restriction levels of 3.39% to 2.0% of BW. When corrected for 3.5% fat, milk production declined (p = 0.05) 3.46 kg/d for each percentage unit of feed restriction. Conclusion: Restricting the feed supply for F1 Holstein/Zebu cows in the middle third of their lactation period altered nutrient intake, nitrogen balance and ingestive behavior but did not affect milk production or feed efficiency. However, considering the observed BW loss and decrease in milk production corrected for 3.5% fat, restriction of no less than 2.5% BW is recommended.

• Animal Bioscience
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• 제34권10호
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• pp.1600-1606
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• 2021

Objective: This study was conducted to enhance our understanding of nitrogen (N) metabolism and mammary amino acid (AA) utilization in lactating cows with divergent phenotypes of residual feed intake (RFI). Methods: Fifty-three multiparous mid-lactation Holstein dairy cows were selected for RFI measurements over a 50-d experimental period. The 26 cows with the most extreme RFI values were classified into the high RFI (n = 13) and low RFI (n = 13) groups, respectively, for analysis of N metabolism and AA utilization. Results: Compared with the high RFI cows, the low RFI animals had lower dry matter intake (p<0.01) with no difference observed in milk yield between the two groups (p>0.10). However, higher ratios of milk yield to dry matter intake (p<0.01) were found in the low RFI cows than in the high RFI cows. The low RFI cows had significant greater ratios of milk protein to metabolizable protein (p = 0.02) and milk protein to crude protein intake than the high RFI cows (p = 0.01). The arterial concentration and mammary uptake of essential AA (p<0.10), branched-chain AA (p<0.10), and total AA (p<0.10) tended to be lower in the low RFI cows. Additionally, the low RFI cows tended to have a lower ratio of AA uptake to milk output for essential AA (p = 0.08), branched-chain AA (p = 0.07) and total AA (p = 0.09) than the high RFI cows. Conclusion: In summary, both utilization of metabolizable protein for milk protein and mammary AA utilization are more efficient in cows with lower RFI than in the high RFI cows. Our results provide new insight into the protein metabolic processes (related to N and AA) involved in feed efficiency.

• Asian-Australasian Journal of Animal Sciences
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• 제32권8호
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• pp.1122-1127
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• 2019

Objective: The objective of current study was to investigate the lactation performance and rumen fermentation characteristics of dairy cows fed a diet with alfalfa hay replaced by corn stover but supplemented with molasses. Methods: Sixteen Holstein cows in mid-lactation were randomly assigned to 1 of 2 dietary treatments: i) alfalfa based diet (AH), and ii) corn stover based diet supplemented with molasses (CSM). The experiment was conducted according to a $2{\times}2$ crossover design with 22-d each period, consisting of 17 d for adaptation and 5 d for data and samples collection. Results: Dry matter intake and milk yield were higher for cows fed AH than CSM (p<0.01). Milk protein content and nitrogen conversion were higher (p<0.05), while milk urea nitrogen was lower (p<0.01) for cows fed AH than CSM-fed cows. Contents of milk total solids, fat and lactose were not different between two groups (p>0.10). Total rumen volatile fatty acid concentration tended to be higher (p = 0.06) for cows fed AH than CSM-fed cows. Molar proportion of acetate was lower (p = 0.04), but valerate was higher (p = 0.02) in cows fed AH than CSM-fed cows. Rumen concentration of propionate, and isobutyrate, and ratio of acetate to propionate tended to be different (p<0.10) between two groups. The feed cost per kilogram of milk was lower in CSM than AH (p<0.01). No differences were found in feed efficiency and most plasma parameters tested (p>0.10). Conclusion: In comparison with AH diet, CSM diet could be fed to dairy cows without negative effect on feed efficiency, ruminal fermentation, but economically beneficial, indicating that CSM could be an alternative choice for dairy farms instead of AH to feed midlactation dairy cows.

• 한국초지조사료학회지
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• 제37권3호
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• pp.208-215
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• 2017

This study was designed to investigate the carryover effects of high-forage to concentrate (F: C) diet in bred heifers on feed intake, feed efficiency (FE) and milk production of primiparous lactating Holstein cows. The experiment was conducted for 589 days (d) from onset of pregnancy through to the end of first lactation. Twenty-four bred heifers (Body weight: $BW=345.8{\pm}45.4kg$ and $15{\pm}1.2mon$ of age) randomly assigned to two groups of 3 pens containing 4 heifers each and fed high forage (HF) diet with F: C ratio of 91.7: 8.3% and low forage (LF) diet with F: C ratio of 77.8: 22.2% throughout the pregnancy period. After calving, lactating cows were fed total mixed ration (TMR) based diet. No differences (p > 0.05) were observed in dry matter intake (DMI) of bred heifers and primiparous lactating cows in both HF and LF groups. The FE of mid-to-late lactation period was higher (p< 0.05) in HF than LF group. However, the HF group showed higher (p < 0.05) milk yield, 4 % fat corrected milk (FCM) and energy corrected milk (ECM) than LF group during the 305 d lactation. The LF group showed higher (p < 0.05) milk fat, crude protein (CP), milk urea nitrogen (MUN), solid not fat (SNF) and somatic cell count (SCC) than HF group. It is concluded that restriction of F: C ratio to 91.7: 8.3% to bred heifers has the potential carryover effects to maintain higher milk yield and FE with no adverse effect on feed intake and milk composition of primiparous lactating Holstein cows.

• 한국작물학회지
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• 제44권2호
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• pp.97-101
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• 1999

No-till direct seeding cultivation of rice has major advantages such as saving of labor and cost by eliminating tillage, preparation of seed bed and trans-planting procedure compared to the conventional transplanting cultivation. A field experiment was conducted to evaluate the effects of straw treatment and nitrogen levels on the rice growth in no-till direct-seeding cultivation. Rice straw, vetch straw, and the mixture of both of the straws were mulched on the surface of soil before seeding while 4 levels of nitrogen fertilizer, 0, 7, 9, and 11 kkg/10a respectively, were applied at 3 split times, 3-weeks after sowing, 5-weeks after sowing and the panicle initiation stage. Mulching of vetch straw significantly reduced seedling establishment of rice which may be attributed to low oxidation-reduction potential of soil by vetch mulching treatment. Vetch straw increased the concentration of soil ammonium leading to an extension of the greenish leaf to panicle initiation stage. Agronomic nitrogen use efficiency (AD $E_{N}$) in heavy-mixed straw mulching plots was lower than other treatments. Grain yield and AU $E_{N}$ in the vetch treatment were less affected by fertilized N levels. Conclusively, it is suggested that heavy straw mulching was not efficient for rice seedling establishment and nitrogen usage.e.