• Asian-Australasian Journal of Animal Sciences
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• v.30 no.5
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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.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.5
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• pp.658-664
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• 2002

This study was conducted to determine a proper feeding regime for lactating Holstein cows during the warm season in Taiwan. In Feeding Trial, 21 lactating Holstein cows were randomly allotted into three feeding regimes in a Completely Randomized Design. The feeding regimes were roughage fed ad libitum along with concentrate fed either twice daily (2C) or four times daily (4C), and total mixed ration (TMR) for 8 weeks. No significant differences among the three feeding regimes were found in body weight changes, and intakes in terms of dry matter, crude protein and net energy. For milk yield and 4% FCM yield, 4C were higher than the other two feeding regimes (p<0.05). No significant differences were found in milk compositions or differences noted in the yields of the respective milk components. TMR was worse than 2C and 4C (p<0.05) in milk production efficiencies in terms of dry matter intake per kg milk yield, crude protein intake per kg milk protein yield, as well as dry matter intake, net energy intake and crude protein intake per kg 4% FCM yield. Three ruminally fistulated Holstein dry cows were randomly assigned into the same three feeding regimes in a 3${\times}$3 Latin Square Design. No significant differences were found among the feeding regimes in ruminal pH, ammonia nitrogen, total VFA concentration, molar percentages of VFA, and acetic acid: propionic acid ratio (C$_2$/C$_3$). Taken all together, roughage fed ad libitum and concentrate fed four times daily was the better feeding regime for lactating cows during the warm season in Taiwan.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.7
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• pp.936-941
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• 2004

Four rumen-cannulated cows (330 kg average weight at 4 years) were used to evaluate the supplement of ensiled cassava tops (ECT) (variety KM 94, 39% DM) on rumen functions, thyroid hormones and liver enzymes. The treatments, arranged in a 4 $\times$4 Latin square design, were ECT at 0, 50, 100 and 150 g CP 100 kg$^{-1}$ body weight (BW), and a basal diet of urea-treated fresh rice straw (UFRS) ad libitum and 1.1 kg dry matter (DM) cassava root meal (CRM) in each 30 day study period. The results showed a continuous decrease in dry matter intake (DMI) of UFRS with increasing level of ECT supplement (p<0.001). The highest total DMI was observed for treatment ECT$_{150}$ (2.68 kg DM 100 kg$^{-1}$ BW day$^{-1}$) followed by treatments ECT$_{100}$, ECT$_{50}$ and ECT$_{0}$, with 2.47, 2.24 and 2.06 kg DM 100 kg$^{-1}$ BW⋅day$^{-1}$, respectively. Increasing levels of ECT supplement increased the concentration of total volatile fatty acids (p<0.05) and ammonia nitrogen (p<0.05) and resulted in a decrease in pH (p<0.05). Overall average plasma triiodothyronine and thyroxine concentrations were 0.80, 0.82, 0.85 and 0.69 ng ml$^{-1}$ (p>0.05), and 50.9, 49.5, 50.7 and 42.4 ng ml-1 (p>0.05) for treatments ECT$_{0}$, ECT$_{50}$, ECT$_{100}$ and ECT$_{150}$, respectively. There were non-significant differences in alanine aminotransferase and aspartate aminotransferase among treatments. It is concluded that ECT is a valuable protein-rich feed supplement to cattle, and the highest level of on average 2.48 kg DM ECT per cow and day (28% of total DMI) did not significantly affect thyroid gland hormones and liver enzymes in cows.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.2
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• pp.206-210
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• 2001

Six Holstein$\times$indigenous multiparous dairy cows, $60{\pm}8$ days in milk, were used in a double $3{\times}3$ Latin square design to investigate the efficiency of milk production. The dairy cows were randomly allocated to total mixed rations (TMR) containing ground corn, ground corn plus cassava chips 50:50 and cassava chips as main sources of total non-fiber carbohydrates. Ether extract and calculated energy intakes for dairy cows fed TMR containing cassava chips were lower (p<0.05) than those fed TMR containing ground corn and ground corn plus cassava chips 50:50. There were no differences (p>0.05) in daily DM intake (3.51, 3.41 and 3.29% BW), in 4% fat corrected milk (19.66, 20.59 and 20.23%), in milk protein (3.37, 3.27 and 3.33%), and in solids-not-fat (9.03, 8.90 and 8.99%) but there were differences in cost of diets per kg of 4% fat corrected milk (40.75, 34.33 and 28.17%; p<0.01) for dairy cows fed TMR containing ground corn, ground corn plus cassava chips 50:50, and cassava chips. It can be concluded that the efficiency of milk production (4% fat corrected milk per dry matter intake) for dairy cows fed TMR containing cassava was greater than for those fed TMR containing corn.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.6
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• pp.904-907
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• 1999

The experiment was aimed at studying the effect of ruminal $NH_3-N$ levels on ruminal fermentation, microbial population, urinary purine derivative excretion, digestibility and rice straw intake in swamp buffaloes. Five, 3 to 4 years old, rumen fistulated swamp buffaloes were randomly assigned according to a $5{\times}5$ Latin square design to rceive five different intraruminal infusions of $NH_4HCO_3$ (0, 150, 300, 450 and 600 g/d) on a continuous daily basis. Rice straw as a roughage was offered ad libitum while concentrate was given at 0.8% BW daily. The results were that as levels of $NH_4HCO_3$ increased, ruminal $NH_3-N$ concentrations increased from 7.1 to 34.4 mg%. The highest digestibility and voluntary straw intakes were found at 13.6 to 17.6 mg% ruminal $NH_3-N$ levels; straw intake was highest at 13.6 mg%. Total bacterial and protozoal counts linearly increased as the ruminal $NH_3-N$ increased and were highest at 17.6 mg%. Total urinary purine derivatives and allantoin excretion were highest (44.0, 37.4 mM/d) at 17.6 mg% ruminal $NH_3-N$. Highest total VFAs (115 mM) were obtained a 13.6 mg% ruminal $NH_3-N$ while blood urea nitrogen significantly increased as ruminal $NH_3-N$ increased. The results from this experiment suggest that optimum ruminal $NH_3-N$ in swamp buffaloes is higher than 13.6 mg%, for improving rumen ecology, microbial protein synthesis, digestibility and straw intake.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.2
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• pp.197-202
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• 1999

Three barrows weighing 45.0 kg, fitted with simple T-cannulas in both the duodenum and terminal ileum, were assigned to diets in a $3{\times}3$ Latin Square design experiment to determine the effect of two calcium levels (0.8% vs 0.4%) on phytase activity and nutrient balance in growing pigs. The control diet contained 0.8% calcium, with no added inorganic phosphorus (0.45% total phosphorus) and no added phytase. The two additional experimental diets contained microbial phytase (750 phytase units/kg) and supplied either 0.8% or 0.4% calcium. With added microbial phytase, ileal and total tract digestibility of rotal phosphorus were improved by 20.9 and 13.8 percentage units, respectively (p=0.01). The apparent duodenal and ileal digestibility of phytate phosphorus were increased by 51.8 and 49.7 percentage units (p=0.01). Lowering dietary calcium in the presence of microbial phytase increased the digestibility of phytate phosphorus by an additional 10.9 (p=0.001) and 5.7 percentage units for duodenal and ileal digestibility, respectively. Supplementation with microbial phytase significantly reduced fecal excretion of nitrogen and phosphorus and increased the percentage of these nutrients retained by the pig. Lowering dietary calcium further increased the percentage of dietary phosphorus retained. Overall, reducing dietary calcium appeared to increase the effectiveness of added microbial phytase in degrading phytate phosphorus. As a result, care should be taken to avoid high levels of dietary calcium when supplementing swine diets with microbial phytase.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.962-966
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• 2000

Effects of the pattern of energy supply on the efficiency of nitrogen utilization for microbial protein synthesis (MPS) were examined in cows consuming grass silage (7.1 kg DM/d) and supplement of 1 kg sucrose per day given as an intraruminal infusion. Three non-lactating cows received three experimental treatments in a $3{\times}3$ Latin square design with each period lasting 14 days. The treatments were (1) the basal diets of silage alone given in one meal each day at 09:30 h (BASAL), supplemented with (2) 1.0 kg sucrose given a 4-h infusion starting at 09:30 h (SYNC), (3) 1.0 kg sucrose given a continuous infusion for 24 h (CONT). Compared with BASAL, sucrose infusions altered (p<0.05) the pattern of variation in ruminal pH and the concentration of ammonia at 4 h after feeding but none of the sucrose treatments resulted in any changes in the ruminal concentration of VFA. All sucrose treatments increased (p<0.05) MPS relative to BASAL by 14% and 33% for SYNC and CONT, respectively, and that for CONT was greater (p<0.05) than for SYNC. It is concluded that synchronization of energy and nitrogen over the shorter term has no further advantage of the efficiency for MPS relative to CONT.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.374-379
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• 2003

Four rumen fistulated Murrah buffaloes were used to study the effect of four diets differing in roughage to concentrate ratio on rumen biochemical changes, microbial enzyme profile and in sacco degradability of feed in a $4{\times}4$ Latin Square design. The animals were fed four diets consisting of 80:20, 70:30, 60:40 and 50:50 ratios of wheat straw and concentrate mixtures, respectively. Wheat straw and concentrate mixture were mixed with water (0.6 l/kg feed) and complete feed mixture was offered to the animals at 8:00 h and 16:00 h in two equal parts. The variation in pH of rumen liquor (difference of maximum and minimum during 0-8 h post feeding) increased with increasing level of concentrate mixture in the diet. There was no effect of diet composition on volatile fatty acids, total nitrogen and trichloro-acetic acid precipitable nitrogen in the rumen liquor, but ammonia nitrogen increased with increasing level of concentrate mixture in the ration. Major portions of all fibre degrading enzymes were present in the particulate material (PM) of the rumen contents, but protease was absent in PM fraction. The activities of micro-crystalline cellulase, acetyl esterase and protease increased with increase in the level of concentrate mixture, but the activities of other enzymes (carboxymethylcellulase, filter paper degrading activity, xylanase, $\beta$-glucosidase and $\beta$-xylosidase) were not affected. The in sacco degradability and effective degradability of feeds increased with increasing level of concentrate mixture in the ration.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.6
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• pp.837-844
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• 2006

Four, lactating dairy cows were randomly assigned according to a $2{\times}2$ Factorial arrangement in a $4{\times}4$ Latin square design to study supplementation of urea level (U) at 2 and 4% and sodium dl-malate (M) at 10 and 20 g/hd/d in concentrate. The treatments were as follows U2M10, U2M20, U4M10 and U4M20, respectively. The cows were offered the treatment concentrate at a ratio to milk yield at 1:2.5 and urea-treated rice straw was fed ad libitum. The results have revealed that rumen fermentation and blood metabolites were similar for all treatments. The populations of protozoa and fungal zoospores were significantly different as affected by urea level and sodium dl-malate. In addition, the viable bacteria were similar for amylolytic and proteolytic bacteria. Cellulolytic bacteria were significantly affected by level of sodium dl-malate especially Selenomonas ruminantium and Megasphaera elsdenii while Butyrivibrio fibrisolvens was significantly affected by level of urea supplementation. In conclusion, the combined use of concentrate containing high level of cassava chip at 75% DM with urea at 4% in concentrate and sodium dl-malate at 20 g/hd/d with UTS as a roughage could improv rumen ecology and microbial protein synthesis efficiency in lactating dairy cows.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.1
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• pp.5-11
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• 1993

First crop of alfalfa (Medicago sativa L.) was harvested, wilted and ensiled with or without NaOH or $NH_3$, and fed to three rumen fistulated goats in a $3{\times}3$ Latin-square design. Each alkali treatment (2.44% of alfalfa dry matter) was made by spraying its solution prior to ensiling. Silage pH, $NH_3-N$ and butyric acid concentration were increased with each alkali addition, and NaOH-treated silage showed the lowest chemical quality. Compared with untreated silage, digestibilities of organic matter, ADF and cellulose were depressed by both alkali treatments, and the reductions in NaOH-treated silage were significant. Crude protein digestibility was also significantly decreased in NaOH-treated silage, but the goats receiving the silage excreted less nitrogen in urine than those on the other two silages. Nitrogen retention of goats was not different among the treatments. Ruminal solubility and potential degradability of dry matter and nitrogen determined with the in situ bag technique were reduced, and rate of degradation of the two components were increased by the NaOH treatment. Addition of $NH_3$ provided ruminal soluble nitrogen to the silage, but the rate of degradation was similar to that of untreated silage. These results suggest that NaOH treatment would denature the protein and reduce the susceptibility to microbial degradation in the rumen, while no positive effect of alkali treatment on fiber digestion and nitrogen utilization was observed in this study.