Utilization of urea nitrogen in young calves

The influence of an increasing intake of urea in feed rations for calves on its levels in blood plasma and urine, development of health condition, weight gains and on other biochemical characteristics in the blood of calves was studied. The experimental group (n = 4) received urea in feed ration from the 17th day of age, at the beginning in the preparation Syrur, later on (from the 66th day) in the synthetic form only. The feed ration of the control group (n = 3) differed only in the zero content of urea. Over the period of ten weeks the blood was sampled for biochemical examination twice a week, since the 52nd day of age urine was also taken at the same intervals. Starting the 24th day of age, the levels of urea in the blood plasma of experimental animals were significantly higher (P less than 0.05). The concentrations of urea in the urine of the animals belonging to the experimental group were also higher, however, the differences in the average values were not significant. In both groups of animals under study no significant differences in the content of vitamin A, concentration of total protein, glucose, bilirubin, activities of aspartate aminotransferase (AST), gammaglutamyl transferase (GMT) and lactate dehydrogenase (LD) were observed. The average daily weight gains were higher in the calves of the control group, however, the differences were not significant. Over the whole experimental period the health condition of both groups of calves was good.     

Optimizing the growth and immune system of dairy calves by subdividing the pre-weaning period and providing different milk volumes for each stage

In systematically considering the advantages and disadvantages of complementarity in high or low milk feeding, novel milk feeding schemes involving altering the volume of supplied milk in different stages of the pre-weaning period but maintaining the total milk feeding volume were tested. Twenty-seven newborn male Holstein calves were selected and randomly assigned to 3 treatments. Calves in the control (CON) group were fed 7 L of milk daily from 4 to 66 d of age. Calves in the low-high (LH) group were fed 6 L of milk daily at the beginning, and then the daily feeding volume was later increased to 7 to 8 L of milk, which served as the early-period low-volume feeding group. The calves in the high-low (HL) group were fed 7 to 8 L daily at the beginning, and then the daily feeding volume was decreased to 6 L of milk, which served as the early-period high-volume feeding group. Then all calves were fed 3 L of milk daily from 67 to 70 d of age, weaned at 70 d of age, and then fed starter feed to 100 d of age. All calves had access to the starter feed from 15 to 100 d of age. The diarrheal condition of calves was recorded daily and the growth performance including the starter feed intake and body weight of calves was recorded at 70 and 100 d of age. Then, five 100-d-old calves from each treatment were sampled for measurement of plasma indices, ruminal morphology, and volatile fatty acids. When compared with the CON and LH groups, calves in the HL group exhibited a significantly increased body weight and lower diarrhoeal rate. When compared with the CON group, calves in the HL group exhibited a significantly increased average daily feed intake, ruminal epithelium papillae length, total volatile fatty acids, and percentages of propionate and butyrate. Moreover, the significantly increased plasma immunoglobulin G (IgG) content and a trend of decreased tumor necrosis factor-α (TNF-α) content (P = 0.083) were also identified in the HL group when compared with the CON group. Overall, the early-period high-volume feeding for calves produced greater body weight gain and a lower incidence of diarrhea.     

The effect of monensin on performance and selected biochemical and hematological parameters in the blood of calves]

The aim of this study was to find out the influence of monensin, a ionophore antibiotic, on calf performance and selected physiological parameters. Monensin is a product of Streptomyces cinnamonensis. It has effects on all Gram-negative microbes, such as Escherichia coli, salmonellas, pseudomonads and vibria. It has a small effect on Gram-positive microbes. At the beginning of the experiment eight young crossbred bulls (C x N) at the age of three weeks were weighted and divided into two groups, experimental and control ones. Calves were kept in individual boxes and fed acidified whole milk (2 ml of 85% formic acid per 1 litre of milk). They had a free access to concentrates (COT), hay and drinking water. The calves received 3 lt. of whole milk twice a day until the age of eight weeks. 0.5 mg of monensin per 1 kg live weight were served orally to calves of the experimental group every day. Monensin was made by the Spofa Corporation, Prague. Daily intake of feed was recorded and the calves were weighted once a week. Blood samples were taken from the jugular vein before the beginning of the experiment, and in the period from the fifth to the tenth week of age, always before morning feeding. The average daily live weight gain was 0.452 kg and 0.471 kg for the control and experimental group, respectively, during the milk feeding period, the index being 104.2 (Tab. I). Tab. II shows the average feed intake per 1 kg live weight gain.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lysozyme in the colostrum and blood of calves and dairy cows

During examination of lysozyme concentration we have found out that 90.3% of calf sera had the lysozyme concentration to 0.5 microgram . ml-1, 5.7% of sera showed zero values and only 4.0% of sera values from 0.5 to 1.4 microgram . ml-1. A higher lysozyme content was recorded in sera of calves up to the age of ten days in comparison with sera of calves after the second week post natum. The lysozyme concentration showed in calves a two-phase increase in the age dynamics up to the seventh to eighth week of life with a peak in second and fifth to eighth week of age. The increase rate in the first phase and the time onset of increase in the second phase were in negative, and/or positive relation to the level of immunity obtained through colostrum. The lysozyme concentration in serum of dairy cows was on fourth day post partum as much as ten times higher than in serum of their progenies 48 hours after parturition. In first colostrum the lysozyme concentration fluctuated within the range of 0.15 to 0.65 microgram X ml-1, with an average of 0.30 microgram X ml-1. The concentration of lysozyme and immunoglobulins of the IgG and IgM class in colostrum showed a contrary trend in first and second milk yield, with a tendency towards increase for lysozyme and towards decrease for immunoglobulins.     

不同断奶日龄对奶公犊生长性能和体尺指标的影响

30头新生荷斯坦奶公犊出生日期和体重相近,随机分成6组,对照组按常规饲喂鲜牛奶,60日龄断奶;各试验组分别于10、20、30、40和50日龄断奶,试验期为60d。结果表明:试验结束时,20日龄断奶组、30日龄断奶组的体重、平均日增重均显著高于对照组,40日龄断奶组、50日龄断奶组与对照组间无明显差异;各试验组犊牛与对照组在体长和体斜长上无显著差异。     

含β-内酰胺类药物有抗奶对犊牛生长发育和血液免疫指标的影响

试验旨在研究饲喂含β-内酰胺类药物有抗奶对荷斯坦公犊牛生长发育和血液免疫指标的影响。选用3日龄、体重（42.64 kg±1.16 kg）相近的公犊牛18头,随机分为2组。对照组饲喂正常牛奶,试验组饲喂有抗奶,犊牛60日龄断奶,试验期为180 d。试验第10、20、30、40和50天分别采集正常牛奶和有抗奶,测定乳成分、大肠杆菌数和乳中抗生素含量。试验第30、60、90和180天逐头空腹称重,测量体尺,并计算平均日增重（ADG）。试验第7、15、30、60、90和180天于晨饲前对公犊牛空腹静脉采血,制备血清,测定血清免疫指标。结果显示：①试验牛场有抗奶中β-内酰胺类抗生素含量为268.65 μg/L,且有抗奶的乳蛋白含量、体细胞数（SCC）和大肠杆菌数显著高于正常牛奶（P<0.05）;②饲喂有抗奶显著降低公犊牛第30天时的体重和试验60 d内的ADG（P<0.05）,显著降低公犊牛第90天时的体长及第60和90天时的胸围（P<0.05）;③与对照组相比,试验组公犊牛IgA在第30、60和90天时显著升高（P<0.05）,IgM在第7天时显著升高（P<0.05）,IgG在第30和60天时显著升高（P<0.05）;IL-2和TNF-α在第15和30天时均显著升高（P<0.05）。结果提示,饲喂有抗奶明显降低犊牛哺乳前期日增重,且在一定程度上提高犊牛断奶前后的血清免疫指标水平。     

Effect of ad lib and restricted milk feeding on the course of illness and body weight in young calves with diarrhea

Two different feeding regimens for calves (age up to 21 days) suffering from acute diarrhea were evaluated with respect to course of illness and change in body weight. The patients of the experimental group were given whole milk ad libitum three times a day. The patients of the control group were offered whole milk at a rate of 13% their body mass per day divided into three meals. In addition, both groups were offered an oral rehydration solution at a rate 9.5% of body mass per day, also divided into three portions. Data from 60 calves (30 in both groups) were available for statistical analysis. The duration of illness in the experimental group was 10.9 +/- 6.0 days vs. 10.0 +/- 5.2 days in the control group. The daily increase of body mass in the experimental group averaged 0.607 +/- 0.452 kg, the one in the control group 0.230 +/- 0.231 kg (p = 0.0002). The calves of the experimental group required 13.16 +/- 11.18 I milk per kg weight gain, the calves of the control group 21.39 +/- 12.80 I. Six calves of the experimental group and two calves of the control group subsequently had a relapse. On the basis of the results obtained, a feeding regimen for calves suffering from acute diarrhea is suggested.     

The effect of biotechnological treatment of milk-replacer feeding mixtures on hematologic and biochemical parameters and its utilization in calves

A trial was performed with cellulase administration (3 cx per g of ingested feed dry matter) to early weaned calves fed minimum amounts of milk replacer (21 kg per milk nutrition period) and sweet (C, D) and sour (A, B) diets. The groups B and D were supplemented with an enzyme till the age of 90 days. The calves were given free choice of COT concentrate mixture, hay and water. Liveweight gains, feed and nutrient intake and health condition of calves were the characteristics investigated in this trial. Hematocrit value, hemoglobin, glucose and urea contents were determined in blood, in blood plasma buffer capacity was investigated. Although the differences in calf performance are not statistically significant, the best growth of calves in the vegetable nutrition period was observed in calves in group D. Nutrient conversion was also higher in calves of group D in the vegetable nutrition period. In conversion of nutrient consumption per 1 kg liveweight gain the difference in the intake of digestible crude protein and starch units between the group of calves fed sweet milk without enzyme addition in the milk nutrient period (A--digestible crude protein 0.40 +/- 0.005; starch units 1.74 +/- 0.008) and group D (sour diet + 3 cx cellulase--digestible crude protein 0.34 +/- 0.007; starch units 1.52 +/- 0.044) was statistically significant (P less than 0.025 and P less than 0.05) in favour of group D. An analysis of the results of hematological and biochemical investigations during the trial demonstrates that the sour diet is better in view of changes in glucose concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)     

初乳饲喂次数对娟姗犊牛生产性能的影响

为研究探讨初乳饲喂次数对娟姗犊牛生产性能的影响,试验选取初生重接近的健康娟姗犊牛20 头,随机分为4 组,分别为对照组、试验I组、II组和III组,每组5 头犊牛,试验期为60 天。4 组犊牛出生当日饲喂两次初乳,首次初乳量按照体重的10.0%进行灌服,第2次初乳于出生后6~8 h按照体重的5.0%进行饲喂。4 组犊牛出生当日在产房饲养,2日龄时均转为室外犊牛岛单栏饲养。2日龄后,对照组每天上午06:00和下午16:00时各饲喂常乳1次,2~6日龄每次饲喂1.50 L,7~20日龄每次饲喂1.80 L,21~35日龄每次饲喂2.50 L,36~60日龄每次饲喂3.00 L,自7日龄开始犊牛自由采食颗粒料。试验Ⅰ组、Ⅱ组、Ⅲ组分别继续饲喂初乳至犊牛2日龄、4日龄、6日龄后再饲喂常乳,饲喂时间和饲喂量与对照组一致。结果表明:(1)在饲喂初乳后48 h、72 h、96 h,试验组与对照组犊牛血清免疫球蛋白g(IgG)均差异显著(p<0.05),120 h、144 h、168 h,试验Ⅰ组与对照组比较,犊牛血清IgG含量差异不显著(p>0.05),试验Ⅱ组、Ⅲ组血清IgG含量与对照组相比,差异极显著(p<0.01)。(2)随着初乳饲喂次数的增加,可有效降低犊牛20日龄内腹泻发生率,试验Ⅰ组、Ⅱ组、Ⅲ组较对照组比较犊牛腹泻发生率分别降低9.5%、22.5%、36.5%,治疗犊牛腹泻总成本较对照组分别下降12.0 元、43.2 元、76.8 元,3 组试验组犊牛成活率为100.0%。(3)初乳饲喂次数的增加,使0~60日龄娟姗犊牛平均日增重(ADG)升高,试验组与对照组相比较,日增重均差异极显著(p<0.01),分别增加16.7 g、33.3 g、80.0 g。试验Ⅱ组、Ⅲ组较试验Ⅰ组ADG差异也极显著(p<0.01)。综合考虑,建议娟姗犊牛饲喂初乳至6日龄,可降低犊牛腹泻发生率、减少治疗费用,提高犊牛成活率及ADG。     

The effect of low temperatures on biochemical indicators in the blood of calves]

Twenty calves, heifers of the Holstein-Friesian breed and crossbreds with the Slovak Pied breed, were divided into two groups at the average age of 19 days. The trial group was kept outdoors in wooden hutches and the control group was housed in an insulated building. Blood was sampled at the age of 20, 33, 48 and 60 days at the outdoor temperatures of 3 degrees C, -2 degrees C, -5 degrees C and -8 degrees C. The calves kept in hutches where temperatures were always lower than in the insulated calf-house had the higher level of nonesterified fatty acids in all observations. The largest, highly significant difference was determined at the age of 60 days at the outdoor temperature of -8 degrees C (271 mumol/l vs. 224 mumol/l), and the significance of differences was also observed in the first and third blood samplings at the temperatures of 3 degrees C and -5 degrees C. The differences were highly significant in the first group between the first and fourth, and second and fourth samplings. In the calves kept in the insulated building the difference was significant between the first and fourth observation because the content of free fatty acids was also gradually increasing in this case (Tab. I). Glycaemia values were also higher in the calves kept in hutches (Tab. II). The most noticeable (significant) difference was determined at the age of 48 days at the outdoor temperature of -5 degrees C (4.3 mmol/l vs. 3.9 mmol/l). Significant differences within the group were recorded only in calves from the trial group kept in hutches. Insulin concentrations increased gradually with the older age of animals (Tab. II). At the age of 20 days the values were identical in fact in both groups and the highest concentrations were recorded at the age of 60 days. The differences between the groups were not significant, the largest difference was observed at the end of milk feeding period at the age of 60 days (19 microUI/l in calves from hutches and 15.6 microUI/l in calves from the insulated building). Triiodothyronine concentrations decreased from the starting values of 0.8 nmol/l and 0.76 nmol/l in both groups at the age of 33 days to the values of 0.61 and 0.62 nmol/l.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effects of two different rearing protocols for Holstein bull calves in the first 3 weeks of life on health status,metabolism and subsequent performance

The aim of this study was to investigate the impact of weight gain of calves within the first 3 weeks of life on health status and subsequent performance. Holstein bull calves were reared either intensively (IR; individual hutches and ad libitum milk feeding for the first 3 weeks of life; n = 24), or according to the established protocol [ER; 4 l milk/day in hutches during week 1 and 720 g/day milk replacer (MR) from day 8 to 21 in a group pen; n = 24]. Water, hay and concentrates were freely available to all calves. From week 4, calves of both groups were housed together in a group pen and fed 720 g MR/day; step‐down weaning was performed between week 5 and 10. Key metabolic blood parameters were analysed on day 2, 12, 21 and 70 of life. After weaning, all animals were fed concentrates and corn silage until slaughter at an age of 8 months. Within the first 3 weeks, average daily weight gain was threefold higher in IR calves in relation to ER calves (1.28 vs. 0.38 kg/day, p < 0.001). Neither incidence nor duration of scouring differed significantly between groups. Starter intake (week 4–10) was higher in IR calves in relation to ER calves (49.7 vs. 38.0 kg/calf, p = 0.006). Serum glucose, urea, albumin and insulin were higher at an age of 21 days in IR calves in relation to ER calves; no differences were obvious at an age of 70 days. Plasma GH and IGF‐I concentrations revealed an uncoupling of the somatotropic axis in ER calves within the first 3 weeks of life. At slaughter, body weight of IR calves tended to be higher than that of the ER calves (320 vs. 309 kg, p = 0.07). In conclusion, intensive feeding and individual housing during the first 3 weeks of life had positive long‐term effects on subsequent performance.     

Effects of a high milk intake during the pre‐weaning period on nutrient metabolism and growth rate in Japanese Black cattle

This study aimed to determine the effects of feeding an increased volume of high‐fat milk during the early post‐natal life on metabolite concentrations in the blood, the expression of key genes regulating intermediary metabolism in the skeletal muscles, and the rate of growth of Japanese Black cattle. All calves were fed a high‐fat milk replacer (crude protein, 26%; crude fat, 25.5%; total dissolved nitrogen, 116%). Control calves (n = 4) were nursed with 500 g milk replacer until 3 months of age, whereas calves in the experimental group (n = 4) were nursed with 1800 g milk replacer until 3 months, and then the volume was gradually reduced until 5 months. Body weight was significantly higher in the experimental group than in the control group at 7 months. Plasma glucose concentrations were significantly lower in the experimental group. Expression of glucose‐transporter‐4 messenger RNA (mRNA) was lower, whereas that of glucose transporter 1, cluster of differentiation 36, and carnitine palmitoyltransferase‐1b mRNA was significantly higher in the Longissimus thoracis of the experimental group. Nutritional status during early post‐natal life appears to strongly influence the growth rate and glucose and lipid metabolism in Japanese Black cattle.     

不同饲喂模式对断奶前犊牛消化代谢及生长性能的影响

本试验旨在研究不同饲喂方式对断奶前犊牛生长性能的影响。试验选择46头体重和出生日期相近的犊牛,随机分成两组,每组23头。其中,Ⅰ组采用传统饲喂模式(粉状开食料+干草+牛奶),从4日龄开始补充粉状开食料,10日龄开始补充苜蓿干草和精饲料,干草自由采食;Ⅱ组采用现代饲喂模式(颗粒型开食料+牛奶),从4日龄开始补充颗料型开食料。两组均60日龄断奶。结果表明,Ⅰ组犊牛日均干物质采食量显著高于Ⅱ组(P<0.05),但两组的平均日增重、体高、体斜长、胸围、前管围均无显著差异(P>0.05);血清中葡萄糖(GLU)、甘油三酯(TG)水平组间无差异(P>0.05),45d、60dⅡ组总蛋白(TP)浓度显著高于Ⅰ组(P<0.05),45dⅠ组尿素氮(BUN)显著高于Ⅱ组(P<0.05);Ⅱ组CP、EE和P的表观消化率显著高于Ⅰ组(P<0.05);Ⅱ组犊牛腹泻率(2.39%)低于Ⅰ组(3.12%)。试验表明,断奶前饲喂颗粒开食料有利于降低犊牛腹泻的发生率,提高犊牛对固体饲料的适应性。     

Effect of Different Addition Schemes of Mannan Oligosaccharide on Growth Performance,Fecal Microorganism and Serum Immune Indexes of Calves

This experiment was conducted to study the effects of mannan oligosaccharides with different adding schemes on growth performance, fecal microorganism and serum immune indexes of calves.Twenty newborn Holstein calves were randomly divided into 4 groups with 5 replicates per group.The claves in group Ⅰ（control group）were not fed the mannan oligosaccharide.The calves in group Ⅱ were fed 5 g mannan oligosaccharide added into the milk,and that of group Ⅲ were fed 5 g mannan oligosaccharide added into the starter diet while calves of group Ⅳ were fed 2.5 g mannan oligosaccharide added into the milk and the starter diet,respectively.The feeding trial lasted for 56 days.The results showed as follows:①During the whole experiment period,body length an body structure of calves had no significant difference between the groups（P>0.05).②During the whole experiment period,the average daily dry matter intake（ADMI）and average daily gain（ADG）in the experiment groups was higher than the control group,the F/G was lower than the control group,and group Ⅱ was the best of the three experiment groups.③On 21th day,the number of Bifidobacterium in feces of the calves in the group Ⅰ was significantly lower than that in other groups（P<0.05),and that of group Ⅱ was the highest;The number of E.coli in feces of the calves in the group Ⅰ was significantly higher than that in other groups（P<0.05),and the group Ⅱ was the lowest.On 56th day,the number of Bifidobacterium of experimental groups were higher than that of control group.The change of E.coli number of four groups were as the same as 21th day.④On 21th day,the serum IgA content of experimental groups were higher than group Ⅰ,and that of group Ⅱ were significantly increased（P<0.05);IgG had a similar change with the IgA;The serum IgM content of group Ⅳ was significantly higher than group Ⅰ（P<0.05), while that of group Ⅲ was lower than control group;On 56th day,the serum immune indexes of experimental groups were all higher than control group（P>0.05).In conclusion,adding mannan oligosaccharides could promote calf growth performance,gut health and immunity,while adding mannan oligosaccharide to milk had better effects.     

甘露寡糖添加方式对哺乳期犊牛生长性能、粪便菌群及血清免疫指标的影响

本试验旨在研究甘露寡糖的不同添加方式对哺乳期犊牛生长性能、粪便菌群及血清免疫指标的影响。试验选用日龄、体重相近,健康状况良好的新生荷斯坦公犊牛20头,随机分为4组,每组5个重复。Ⅰ组（对照组）不添加甘露寡糖;Ⅱ组在牛奶中添加5 g甘露寡糖;Ⅲ组在开食料中添加5 g甘露寡糖;Ⅳ组在牛奶和开食料中各添加2.5 g甘露寡糖。试验期56 d。结果表明：①在整个试验周期内,犊牛体长与体躯指数的组间差异不显著（P>0.05）。②整个试验周期内,各试验组犊牛平均干物质日采食量、平均日增重均高于Ⅰ组;各试验组料重比均低于Ⅰ组;且Ⅱ组试验效果优于其他两个试验组。③试验第21天时,各试验组犊牛粪便中双歧杆菌数均显著高于Ⅰ组（P<0.05）,且Ⅱ组显著高于其他两个试验组（P<0.05）;各试验组粪便中大肠杆菌数均显著低于Ⅰ组（P<0.05）,且以Ⅱ组为最低。试验第56天时,各试验组粪便双歧杆菌数均高于Ⅰ组,各试验组粪便中大肠杆菌数均低于Ⅰ组（P>0.05）,且Ⅱ组大肠杆菌数最低。④试验第21天时,Ⅱ组血清中IgA浓度显著高于Ⅰ组（P<0.05）,Ⅲ、Ⅳ组血清中IgA浓度略高于Ⅰ组（P>0.05）;IgG变化规律与IgA相似;Ⅳ组血清中IgM浓度显著高于Ⅰ组（P<0.05）,Ⅲ组在数值上略低于Ⅰ组（P>0.05）。试验第56天时,各试验组血清中免疫球蛋白含量均高于Ⅰ组（P>0.05）。综上所述,在犊牛饮用奶中添加甘露寡糖对于提高动物的生长性能及机体的抵抗力的效果优于其他两种方案。     

Hemato-biochemical changes, disease incidence and live weight gain in individual versus group reared calves fed on different levels of milk and skim milk

A 2 × 3 factorial design was used to study the impact of rearing systems, individual (I) versus group (G) and different levels of milk/skim milk feeding (F1, F2 and F3) on hemato‐biochemical profile, disease incidence and average daily gain of crossbred (Bos indicus × Bos taurus) calves. Six calves were taken in each group on the basis of their birth weight and housed in individual (2.20 × 1.16 m²/calf) or in group pens (2.20 × 1.03 m²/calf). After 3 days of colostrum feeding, calves were allocated to one of three different milk feeding schedules: milk fed up to 8 weeks of age (F1), milk up to 4 weeks followed by 50% replacement by skim milk up to 6 weeks and 100% thereafter (F2) and 100% replacement of milk with skim milk after 4 weeks (F3). Calf starter and cereal green fodders were fed ad libitum from the second week of age and continued for 14 weeks. Parameters on health and disease profiles of calves (disease incidence, duration of illness, response to treatment and recovery) and weekly live weight change were recorded. Calf scour predominated (52.8%), followed by joint ill (25.0%) and respiratory infections (19.4%). The disease incidence was greater (P < 0.01) in individually housed calves (94.4 vs. 55.9%). The management of navel ill required longer recovery (7.01 days) followed by joint ill (4.87 days) and respiratory infection (4.86 days). The average daily gain during 0–14 weeks of age was higher (P < 0.01) in group‐housed calves (433 ± 22 vs. 355 ± 31 g), while the effect of feeding was not significant. Blood samples collected at 4, 8 and 14 weeks of age showed some periodic higher concentrations (but within normal range) of plasma urea and total protein in group housed calves on F2 and F3 feeding schedules in response to high protein intake. Other parameters remained non‐significantly different. Thus, group‐housed calves can be reared successfully with comparatively better performance and less illness than individually housed ones under the present health care and housing management system. However, the system should not be used as a substitute for good management, and frequent observations of calves should be an integral part of any successful rearing program.     

脂肪水平对早期断奶犊牛生长性能及血清生化指标的影响

早期断奶犊牛饲喂不同脂肪含量代乳品,研究脂肪水平对犊牛生长性能、血清生化指标及饲料进食量的影响,为犊牛生长规律和脂肪需要提供科学依据,为实际生产中犊牛早期断奶和培育提供技术指导。试验选取12头新生荷斯坦公犊牛,分为EE9、EE13、EE17 3组,每组４头,分别饲喂蛋白质水平相同、脂肪含量为9%、13%及17%的3种代乳品。每日记录犊牛开食料的采食情况,并于犊牛10、20、30、40、50、60日龄清晨空腹测定犊牛体重及体尺指标,同时采集犊牛的血液样本进行分析。研究结果表明,3组犊牛哺乳期的饲料日进食量分别为706.9、666.9、569.3 g;10~60日龄的平均日增重分别为498、544、488 g,EE13组犊牛日增重高于EE9、EE17组的犊牛;犊牛60日龄时,EE13组犊牛的体高、体斜长及管围均高于其它2组。血清尿素氮、血糖、甘油三酯的水平不受代乳品脂肪含量的影响,但日龄对哺乳期犊牛甘油三酯含量的影响差异显著(P<0.05)。随日龄的增加,犊牛的生长速度和饲料的进食量逐渐增加,低脂肪的代乳品(EE9)不能满足犊牛的能量需要,高脂肪的代乳品（EE17）抑制了犊牛对开食料的采食量,饲喂脂肪含量13％的代乳品（EE13）对犊牛生长发育优于其它2组。脂肪含量对犊牛血清生化指标的影响不显著。     

不同代乳品及饲喂方式对荷斯坦奶公犊生产犊牛白肉影响的研究

为研究代乳粉(主要含乳类制品)液态饲喂和代乳料(主要含植物类饲料等)干喂对荷斯坦奶公犊生产犊牛白肉的影响,试验选用20头健康无病、体重和出生日期相近的荷斯坦奶公犊,随机分为2组,每组10头,进行了120 d的生长育肥试验。Ⅰ组饲喂市售的代乳粉(粗蛋白质22%,粗脂肪16%);Ⅱ组饲喂配制的代乳料(粗蛋白质22%,消化能16 MJ/kg)。结果表明:①Ⅱ组犊牛0~90 d平均日增重高于Ⅰ组犊牛,91~120 d平均日增重显著低于Ⅰ组犊牛(P< 0.05),但两组犊牛0~120 d平均日增重和试验末重均无显著差异(P> 0.05)。②不同代乳品及饲喂方式对奶公犊营养物质表观消化率均无显著影响(P> 0.05)。③Ⅰ组犊牛的胴体重、屠宰率和眼肌面积均显著高于Ⅱ组犊牛(P< 0.05),分别比Ⅱ组高11.88%、11.04%和8.12%,但两组间的胴体产肉率无显著差异(P> 0.05);两组犊牛背最长肌的pH、剪切力、蒸煮损失和肉色均无显著差异(P> 0.05),但Ⅰ组犊牛的失水率比Ⅱ组犊牛高20.83%(P< 0.01);Ⅰ组犊牛背最长肌中粗脂肪含量极显著高于Ⅱ组犊牛(P< 0.01),但两组犊牛背最长肌中水分、粗蛋白质、粗灰分、钙、磷和铁的含量均无显著差异(P> 0.05)。④Ⅱ组犊牛的饲养成本比Ⅰ组降低45.38%。综上所述,饲喂代乳料的犊牛可获得与饲喂代乳粉犊牛相似的生长性能和肉品质,显著降低饲养成本。     

The effect of experimental inhibition of gastric acid secretion on curd formation in abomasum and weight gain of calves

Eight Holstein bull calves were divided into two groups; a non-treated control group and a famotidine treated group. Fresh milk was fed twice a day. The experiment was conducted between 7 and 14 days of age. During the experimental period the control group was injected with physiological saline, and the famotidine group was injected with famotidine, a histamine-H2-receptor blocker, into the jugular vein 30 minutes prior to each feeding. The control group showed maximum curd formation 2 h after feeding at both 7 and 14 days of age. Curd scores of 7-day-old and 14-day-old calves were significantly lower in the famotidine than in the control group at 2 and 4 h after feeding. Most fecal samples from the famotidine group exhibited an acidic smell. The famotidine group showed significantly lower values for both average weight gain and the rate of weight gain from 7 to 14 days of age. The inhibition of gastric acid secretion decreased curd formation in the abomasum as well as daily weight gain compared to non-treated control calves. This suggested that curd formation in the abomasum is important for the weight gain of newborn calves.     

Production of volatile fatty acids in the rumen of calves during dietary-microbial stimulation and early weaning

The contents of volatile fatty acids in the rumen fluid were studied in calves at an early (seven weeks of age) and traditional weaning term (nine weeks of age). Weaning at the age of seven weeks enabled to save 16.2 kg of milk replacer per calf; there was also a lower content of concentrates in the starter feed with a supplement of Amylastim. The health condition of the calves was good in both groups. The average daily weight gains for the period from the second to the ninth week of age were 0.550 kg in the early weaned calves and 0.690 kg in the calves weaned at a normal time. Early weaning had a positive influence on the development of rumen metabolism. Calves weaned at the age of seven weeks, compared with those weaned at the age of nine weeks, had much higher concentrations of VFA (p less than 0.05) in rumen fluid (at the age of seven weeks: 130.49 mmol per litre vs. 111.53 mmol per litre; at the age of eight weeks: 119.74 mmol per litre vs. 96.98 mmol per litre). Early weaned calves had the statistically significantly (p less than 0.05) higher proportions of propionic acid, butyric acid, i-butyric acid, and valeric acid. Later-weaned calves had the significantly higher (p less than 0.05) contents of acetic acid and i-valeric acid.