• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1689-1694
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• 2004

This study was conducted to develop a novel adjustment factors for 305 days using 138,103 lactation records and 1,770,764 daily records, which were based on environmental circumstances such as herd year, season, age at calving, dry period and lactating stages. The present study showed that the change of persistency of cows at the first parity from total lactacting characteristics was slowly processed, while it was rapidly changed in cows at the second parity stage. Particularly, there was an outstanding difference between the first and second parity cows. Milk yield and composition increased as the age at calving was increased. In addition, milk yield and composition were higher at the first parity on fall compared with others, and those were higher at the more than second parity on fall and winter compared with other parity stages and seasons. The cow of dry group was included into lactating records of more than second parity stage. The data indicated that optimal results arose from 45-70 days of dry period. Milk yield was decreased when dry period was longer or shorter than 45-70 days. The lactating days were divided into 17, 28 and 38 stages to compare the multiplicative correction factors. The factor was effective at 28 stages on the first parity. The total correlation coefficients were 0.93832, 0.95058 and 0.95076 at the present correction factor, 17 stage and 28 stage, respectively. At second parity, the factor was higher in dry group 1 and 3 at 17 stage, and it was higher in dry group 2 at 28 stage compared with others. Therefore, the present study showed that the percent squared bias (PSB), which was calculated from the novel correction factor, was better than previously used correction factors. Also, the present study indicated that the bias of the novel correction factor was improved, and this factor could be more accurate compared with others.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.3
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• pp.390-395
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• 2006

This work was conducted to study the effect of rumen-protected choline (RPC) addition on milk performance and blood metabolic parameters in transition dairy cows. In Experiment 1, fourteen Chinese Holstein dairy cows were supplemented with 0 or 20 g/d of RPC from 7 d before expected calving to 21 d post partum. Feeding of RPC tended to increase milk yield and milk protein percentage, while milk fat and lactose percentage were not changed. Plasma concentrations of glucose tended to increase as cows consumed RPC, while plasma concentrations of triglycerides, very low density lipoproteins, cholesterol and nonesterified fatty acids were not significantly different between the two groups. In Experiment 2, thirty-six Chinese Holstein dairy cows were supplemented with 0, 30, 60 or 90 g/d RPC from 15 d before expected calving to 15 d post partum. Feeding of RPC tended to increase yield of milk and 4% fat-corrected milk for all the lactating cows, and milk composition was similar among the four groups. Plasma concentrations of glucose were remained at a higher level in 30 or 60 g/d RPC-supplemented groups, and nonesterified fatty acids were decreased in the 30 g/d group. Concentrations of triglycerides tended to reduce in 30 and 90 g/d RPC-supplemented animals, and cholesterol was reduced in 0 or 30 g/d group. These results suggest that RPC addition tended to increase milk yield and improve blood metabolic parameters during transition dairy cows, and feeding 30 g/d of RPC may be the optimal.

• Animal Bioscience
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• v.35 no.8
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• pp.1184-1194
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• 2022

Objective: High concentrate diets are widely used to satisfy high-yielding dairy cows; however, long-term feeding of high concentrate diets can cause subacute ruminal acidosis (SARA). The endocrine disturbance is one of the important reasons for metabolic disorders caused by SARA. However, there is no current report about thyroid hormones involved in liver metabolic disorders induced by a high concentrate diet. Methods: In this study, 12 mid-lactating dairy cows were randomly assigned to HC (high concentrate) group (60% concentrate of dry matter, n = 6) and LC (low concentrate) group (40% concentrate of dry matter, n = 6). All cows were slaughtered on the 21st day, and the samples of blood and liver were collected to analyze the blood biochemistry, histological changes, thyroid hormones, and the expression of genes and proteins. Results: Compared with LC group, HC group showed decreased serum triglyceride, free fatty acid, total cholesterol, low-density lipoprotein cholesterol, increased hepatic glycogen, and glucose. For glucose metabolism, the gene and protein expression of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase 1 in the liver were significantly up-regulated in HC group. For lipid metabolism, the expression of sterol regulatory element-binding protein 1, long-chain acyl-CoA synthetase 1, and fatty acid synthase in the liver was decreased in HC group, whereas carnitine palmitoyltransferase 1α and peroxisome proliferator activated receptor α were increased. Serum triiodothyronine, thyroxin, free triiodothyronine (FT3), and hepatic FT3 increased in HC group, accompanied by increased expression of thyroid hormone receptor (THR) in the liver. Conclusion: Taken together, thyroid hormones may increase hepatic gluconeogenesis, β-oxidation and reduce fatty acid synthesis through the THR pathway to participate in the metabolic disorders caused by a high concentrate diet.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.1
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• pp.107-112
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• 1992

Feeding of bypass protein to lactating animals have been suggested by many research scientists as a way to increase the nutrient supply at the intestinal level thereby enhance animal production in ruminant animals. A feeding trial with a formulated bypass protein feed on straw based ration was carried out by using lactating cross bred cows at the stage of 4th month of their lactation. Bypass protein feed was fed at 5 different levels. Urea Molasses Block was used as a nitrogen source to the rumen microflora. In order to reduce the heat increment straw intake was restricted to all the animals. Urea Molasses Block intake was noticed varying in proportion with the bypass protein feed intake. Milk production was observed increasing in accordance with the level of bypass protein feed intake. However, the maximum response was noticed in cows that were fed 3 kg bypass protein feed. The nutrient availability at this stage was below the NRC (1988) requirements. Other remarkable finding was that the cows maintained the persistency of milk production even after 3rd month of lactation when the ambient temperature was $40^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.4
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• pp.577-580
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• 1993

Six lactating crossbred cows and six Murrah buffaloes, maintained under similar conditions of feeding and management were studied for body composition by the antipyrine dilution technique. Measurements were made at the start of the experiment when the animals had completed about 50 days in lactation and thereafter at monthly intervals up to 90 days of the experimental period. The percent body water estimates in both species at different time intervals did not change significantly. Percent body fat and protein content also remained unchanged. The correlation coefficient between body composition parameters and various hormones (growth hormone, insulin, $T_3$ and $T_4$) were generally low and non-significant. It was concluded that body composition studies using body water are not sufficiently sensitive to predict changes in body composition of lactating cows and buffaloes and/or the changes in body composition during lactation are not very drastic.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.6
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• pp.895-900
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• 1999

The aim of this study was to evaluate the effect of incorporating wet sorghum distiller's grains (WSDG) as part of their diet on the lactating performance of dairy cows. Twenty-seven Holstein milking cows were selected, all in the early lactating stage, with an average weight of 550 kg, and producing an average of 30 kg of milk daily. The cows were divided into three groups according to milk yield and lactation and were fed different total mixed rations. The diets were formulated according to NRC (1989) recommendations in three rations to (1) control diet, (2) 15% WSDG diet and (3) 30% WSDG diet. The three different diets were all formulated as iso-nitrogen and iso-energetic diets. After one week adaptation period, the experimental feeding was conducted for 8 weeks. Three ruminal cannulated cows were also examined in order to investigate ruminal fermentation of the three total mixed rations. The results showed that the milk yield, as corrected to the 4.0% fat standard, had no significant difference among the control, 15% WSDG and 30% WSDG treatment groups (p>0.05). The daily dry matter intake of the control group was higher than the other groups (p<0.05). with respect to milk composition, milk fat, milk protein and total solids, there was no significant difference among the treatment groups (p>0.05). The energy efficiency of the 30% WSDG group were significantly higher than the other treatment groups (p<0.05). Ruminal pH value showed no difference among the treatment groups (p<0.05). Ammonia-nitrogen concentration in the control group was higher than the other treatment groups (p<0.05). The concentration of total ruminal volatile fatty acid was similar in all three dietary groups.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.10
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• pp.1449-1453
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• 2015

The objective of the present study was to determine the effects of feeding pelletized broccoli byproducts (PBB) on milk yield and milk composition in dairy cows. In Trial 1, an in vitro gas test determined the optimal replacement level of PBB in a concentrate mixture in a mixed substrate with Chinese wild ryegrass hay (50:50, w/w) at levels of 0, 10%, 20%, 30%, or 40% (dry matter basis). When the concentrate was replaced by PBB at a level of 20%, no adverse effects were found on the gas volume or its rate constant during ruminal fermentation. In trial 2, 24 lactating cows (days in milk = $170.4{\pm}35$; milk yield = $30{\pm}3kg/d$; body weight = $580{\pm}13kg$) were divided into 12 blocks based on day in milk and milk yield and randomly allocated to two dietary treatments: a basic diet with or without PBB replacing 20% of the concentrate mixture. The feeding trial lasted for 56 days; the first week allowed for adaptation to the diet. The milk composition was analyzed once a week. No significant difference in milk yield was observed between the two groups (23.5 vs 24.2 kg). A significant increase was found in milk fat content in the PBB group (p<0.05). Inclusion of PBB did not affect milk protein, lactose, total solids or solids-not-fat (p>0.05). These results indicated that PBB could be included in dairy cattle diets at a suitable level to replace concentrate mixture without any adverse effects on dairy performance.

• Journal of Embryo Transfer
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• v.26 no.2
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• pp.91-96
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• 2011

The purpose of this study was to evaluate the effects of days open on subsequent reproductive performance following to estrus synchronization in the 114 lactating dairy cows. The animals were divided into two groups according to the time of estrus synchronization; viz, ${\leq}$ 85 days, and > 85 days postpartum, respectively. The estrus synchronization protocol consisted of insertion of a controlled internal drug release (CIDR) device containing 1.9 g progesterone with an injection of 250 ${\mu}g$ gonadorelin (Day 0), an injection of $PGF_2{\alpha}$ and removal of the device on Day 7, an injection of 250 ${\mu}g$ GnRH on Day 9, and TAI 17 h later. Pregnancy diagnosis was determined at 30 to 60 days after TAI using both ultrasonography and rectal palpation. The body condition score (BCS) gradually increased over the postpartum period. In estrus synchronized cows until 85 days, conception rate on first service, number of service per conception, interval from estrus synchronization to conception, and interval from calving to conception were not significantly different among two farms (P>0.05). In estrus synchronized cows after 85 days postpartum, conception rate on first service, number of service per conception and interval from calving to conception were significantly different ($P{\leq}0.05$) between herds A and B (26.8 vs 50.0%; $2.1{\pm}1.35$ vs $1.37{\pm}0.54$ times, $237.3{\pm}97.8$ vs $164.7{\pm}69.3$ days, respectively). In estrus synchronized cows after 85 days postpartum interval from estrus synchronization to conception was greater (P<0.01) in herd B than in herd A ($63.6{\pm}57.4$ vs $26.1{\pm}24.9$). These results indicate that the time of estrus synchronization for maximized the reproductive performance is before 85 days postpartum and feeding and management is important factor for high reproductive performance.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.3
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• pp.442-451
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• 2019

Objective: This study was conducted to investigate the effect of transport stress on physiological and hematological responses and milk performance in lactating dairy cows. Methods: Ten lactating dairy cows were randomly divided into 2 groups. The treatment group (TG) was transported 200 km for 4 h by truck, and the control group (NTG) was restrained by stanchion for 4 h in Konkuk University farm. Blood and milk samples were collected at 24 h pre-transport; 1, 2, and 4 h during transport; and 2, 24, and 48 h post-transport. Milk yields were measured at 24 h pre-transport, 0 h during transport, and 24, 48, and 72 h post-transport. Results: Leukocyte, neutrophil, and monocyte numbers in the TG were significantly higher than those of the NTG at each experimental time point. Lymphocyte numbers in the TG were significantly (p<0.05) higher than those of the NTG at 48 h post-transport. Additionally, the neutrophil:lymphocyte ratio of the TG was 45% and 46% higher than that of the NTG at 4 h during transport and 2 h post-transport, respectively. There were no significant differences in erythrocyte numbers, hemoglobin concentrations, platelet numbers, and hematocrit percentages between two groups. Cortisol levels in the TG were significantly (p<0.05) higher than those in the NTG. Milk yields in the TG were lower than those in the NTG. The somatic cell count (SCC) of the TG was significantly (p<0.05) higher than that of the NTG at 1 and 2 h during transport; that of the TG increased dramatically at 1 h during transport and gradually decreased subsequently. Conclusion: Transport stress increased blood parameters including leucocyte, neutrophil, and monocyte numbers by increased cortisol levels, but did not affect erythrocytes, hemoglobin and hematocrit levels. Additionally, transport resulted in a decrease in milk yield and reduced milk quality owing to an increase in milk SCC.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.1
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• pp.42-50
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• 2008

Twenty-four, lactating dairy cows were randomly assigned according to a Rrandomized complete block design (RCBD) to investigate the effect of sunflower oil supplementation (SFOS) with cassava hay based-diets on feed intake, digestibility of nutrients, rumen fermentation efficiency and milk production. The treatments were as follows: T1 = Control, using commercial concentrate as a supplement (CON); T2 = Concentrate with cassava hay (CHSO-0); T3 = Concentrate with cassava hay and 2.5% sunflower oil (CHSO-2.5); T4 = Concentrate with cassava hay and 5% sunflower oil (CHSO-5). The cows were offered concentrate feed at a ratio of concentrate to milk production of 1:2 and urea-treated rice straw was fed ad libitum. The results revealed that feed intake, digestibility of nutrients and ruminal pH were similar among all treatments, while ruminal NH3-N was lower (p<0.05) with SFOS. Blood urea-N (BUN) and milk urea-N (MUN) were not significantly affected by SFOS. The ruminal concentrations of volatile fatty acids were significantly different among the treatments. Sunflower oil supplementation significantly increased concentrations of unsaturated fatty acids, and ratio of unsaturated to saturated fatty acids in the milk, particularly the conjugated fatty acids, was significantly enhanced. Furthermore, production costs of treatments with sunflower oil supplementation were lower than for the control. Based on this study, SFOS in cassava hay based-diets improves rumen ecology, milk yield and milk quality, especially in terms of conjugated linoleic acids.