不同诱食剂对乳肉兼用犊牛采食偏好的影响

对于乳肉兼用犊牛而言,能更早的采食犊牛料并提高采食量是实现犊牛早期断奶和提升日增重的关键手段。本试验结合常用的三种犊牛颗粒料饲料添加产品(S1:0.03%乳香味诱食剂;S2:0.015%糖精钠;S3:0.3%包被丁酸钠)从诱食效果方面进行评估,选取效果最好的诱食产品在犊牛颗粒料生产中推广使用。试验结果表明：3种不同诱食剂对乳肉兼用犊牛诱食效果为：0.03%乳香味诱食剂>0.015%糖精钠>0.3%包被丁酸钠。     

Relationship between feeding behaviour and feed intake of dairy cows depending on their parity and milk yield

To investigate the relationship between the parameters of feeding behaviour and feed intake, 70 lactating dairy cows (23 primiparous and 47 multiparous) were monitored from the 2nd to 15th week of lactation. Data were collected by using an automatic feeder and electronic identification of individual cows from 10 July 2005 to 16 January 2006. The resulting data of the cows in primiparous and multiparous condition were categorised into groups based on the mean of their milk yield over the first 15 weeks of lactation: primiparous cows with below-average milk yield (LP) and above-average milk yield (HP) with an average of 28.44 and 34.31 kg energy-corrected milk (ECM) per day, respectively, and multiparous cows with below-average milk yield (LM) and above-average milk yield (HM) with an average of 38.70 and 44.49 kg ECM per day, respectively. The parameters of feeding behaviour were calculated based on the estimated meal criterion from pooled data. Parity, level of milk yield, and day had significant effects on some of characteristics of feeding behaviour and feed intake parameters. There was no significant difference in meal duration either between primiparous and multiparous cows or between LP and HP. However, a significant difference between LM and HM was observed. Cows in HM had shorter feeding times but a larger meal size, higher DMI, and feeding rate. Moreover, these cows displayed a stronger correlation between meal duration, daily mealtime and daily feed intake (r = 0.37 and 0.50, P < 0.001, respectively) than any other cow or group of cows of the study. Meal duration, daily mealtime, meal size and daily DMI increased on average about 32%, 20%, 35%, and 22% respectively, considering all milk yield groups from the 2nd to 15th week of lactation.     

延边黄牛犊牛代乳料饲喂效果的研究

选择16头初生重相近的延边黄牛犊牛随机分成4组,每组4头,对照组犊牛随母哺乳,试验组采用随母哺乳加补饲,试验Ⅰ、Ⅱ、Ⅲ组分别补饲1、2、3号代乳料,进行增重效果和血液指标的比较。试验结果表明:各试验组的4月龄重、全期增重和日增重均高于对照组,其中试验Ⅲ组显著高于对照组(P<0.05);体尺指标测定中,试验Ⅲ组的体长显著高于对照组(P<0.05),试验Ⅰ、Ⅱ、Ⅲ组的腰角宽显著高于对照组(P<0.05);各组血液指标均在正常范围之内。综合评定,3号代乳料饲喂效果最好。     

Economic analysis of feeding pasteurized nonsaleable milk versus conventional milk replacer to dairy calves

OBJECTIVE: To determine growth, morbidity, and mortality rates in dairy calves fed pasteurized nonsaleable milk versus commercial milk replacer and compare economics of feeding pasteurized nonsaleable milk versus commercial milk replacer in dairy calves. DESIGN: Clinical trial. ANIMALS: 438 dairy calves. PROCEDURE: Calves were assigned at 1 to 2 days of age to be fed pasteurized nonsaleable milk or a commercial milk replacer until weaned. Body weight was measured at the time of study enrollment and at the time of weaning, and any medical treatments administered and deaths that occurred prior to weaning were recorded. A partial budget model was developed to examine the economics of feeding pasteurized nonsaleable milk versus commercial milk replacer. RESULTS: Calves fed conventional milk replacer had significantly lower rates of gain (-0.12 kg/d [-0.26 lb/d]), lower weaning weights (-5.6 kg [-12.3 lb]), higher risk for treatment during the summer and winter months (odds ratio [OR], 3.99), and higher risk of death during the winter months (OR, 29.81) than did calves fed pasteurized nonsaleable milk. The estimated savings of feeding pasteurized nonsaleable milk, compared with milk replacer, was dollars 0.69/calf per day. The estimated number of calves needed to economically justify the nonsaleable milk pasteurization system was 23 calves/d. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that dairy calves fed pasteurized nonsaleable milk have a higher growth rate and lower morbidity and mortality rates than do calves fed conventional milk replacer. Feeding pasteurized nonsaleable milk could be an economically viable strategy for dairy calf producers.     

Longitudinal identification of Enterocytozoon bieneusi in dairy calves on a farm in Southern Xinjiang,China

Enterocytozoon bieneusi is the most common species responsible for human and animals microsporidiasis. A total of 250 samples were collected weekly from 25 newborn dairy calves of a farm in Southern Xinjiang, China at one to ten weeks of age. Enterocytozoon bieneusi was identified and genotyped by nested PCR amplification and sequencing of internal transcribed spacer (ITS) region.The cumulative prevalence of E. bieneusi infection was 100% (25/25), and the average infection was 52.0% (130/250). The highest infection rate was recorded at six weeks of age (92.0%, 23/25), and no infection was observed at one and two weeks of age. Sequencing analysis showed nine E. bieneusi genotypes (J, EbpC, PigEBITS5, CHV4, CHC3, CS-9, KIN-1, CH5, and CAM5) were identified. The highest genetic polymorphism was observed at ten weeks of age. Genotype J was the predominant E. bieneusi genotype. Phylogenetic analysis clustered genotype J into Group 2 and other eight genotypes (EbpC, PigEBITS5, CHV4, CHC3, CS-9, KIN-1, CH5, and CAM5), detected in 22 (16.9%, 22/130) samples, into Group 1. Among the genotypes, EbpC, KIN-1, and J have been identified in humans. The highest E. bieneusi infection rate (57.9%, 124/214) was observed in fecal samples with formed feces with no diarrhea (p < 0.01), and high genetic polymorphism was observed in class I fecal samples. The presence of zoonotic E. bieneusi genotypes in dairy calves suggests the possibility of transmitting zoonotic infections to humans. It provides the basic data on dynamic change of E. bieneusi in calves.     

Maize silage particle length modulates feeding patterns and milk composition in loose-housed lactating Holstein cows

This study analysed feeding patterns and feed selective consumption by loose-housed lactating dairy cows fed diets based on maize silage (MS) with different particle length (PL) to establish its effects on overall dry matter intake (DMI) and productive performance. Twelve multiparous Holstein cows were offered a total mixed ration (TMR) with three different PL of MS at harvesting (i.e., long, medium, and short). Results demonstrated greater numbers of day-time meals (i.e., 07:30–19:00 h) when PL was decreased from long to medium (P < 0.05). Night-time (i.e., 19:00–06:30 h) changes in the feeding pattern included an increased amount of feed per meal (P < 0.05) and a tendency to increase eating time per meal (P < 0.10) in cows fed the short-PL diet. Lowering the PL of MS also lowered the selective consumption against physically effective fibre larger than 1.18 mm (peNDF_> 1.18; P < 0.05) and in favour of fine particles (i.e., particles passing through 1.18 mm screen; P < 0.01). Decreasing PL of MS from long to medium and short increased daily DMI as well as the intake of energy and other nutrients contained in the diet including the amount of peNDF_> 1.18 (P < 0.01). The decrease in the PL of the diet also was associated with increased milk protein and lactose yield and milk urea nitrogen (P < 0.05). The actual milk yield and fat-corrected milk were not affected by the diet (P > 0.10). Although lowering of the PL tended to increase daily milk energy output (P < 0.10), the ratio between energy milk output and the energy intake was linearly decreased (P < 0.01), indicating a lower milk efficiency for the lower-PL diets. In conclusion, particle length of MS in a TMR has the potential to modulate circadian feeding patterns, selective consumption of the feed, daily DMI, and milk composition in high-producing dairy cows.     

A spline polynomial model to describe serum IGF-I concentration from birth to slaughter in calves: effects of weaning age,pre-weaning concentrate feeding and breed

The statistical analysis of hormones sampled throughout the production cycle is complicated because factors such as age and weight at the measuring date interfere. Spline curves constructed from pieces of low-degree, random-effects polynomials could be used for a more accurate analysis of data. Concentration of insulin-like growth factor-1 (IGF-1), weight gain, and concentrate intake of Parda de Montaña (PM) (n = 27) and Pirenaica calves (n = 14) were modeled with a spline model according to age at weaning, pre-weaning concentrate feeding, and breed. At birth, calves were randomly assigned to early weaning (EW) at 90 d or traditional weaning (TW) at 150 d. During lactation, half of PM calves received concentrates (S), whereas the remainder received no concentrates (NS). After weaning, calves received concentrates on an ad libitum basis until they reached a weight of 450 kg. The spline model had better likelihood than a polynomial of 6 degrees or a split-plot model. Serum IGF-1 concentration was greatly affected by age at weaning and pre-weaning concentrate feeding, but not by breed. In NS calves, IGF-1 concentration was greater in EW than in TW calves from 120 to 300 d, irrespective of breed. During lactation, S calves had greater IGF-1 concentration than NS calves. After weaning, EWNS calves reached the IGF-1 concentration of EWS calves after 4 mo on concentrates, whereas TWNS calves attained IGF-1 concentration of TWS calves after only 2 mo, because of their increased concentrate intake relative to TWS calves. Concentration of IGF-1 was positively correlated with the immediate weight gains and intake, but it was not a good predictor of performance in the long term.     

A case-control study of Washington dairy herds experiencing drug residue violations in market calves

The purpose of this case-control study was to examine the association between management practices and the occurrence of violative drug residues in calves originating from Washington dairies. In 1992, 74 dairies were identified as first-time offenders sending to abattoirs calves less than 1 week of age that had violative residue levels. Of these, 56 answered a subset of previously validated management questions from the 1991–1992 US National Animal Health Monitoring System National Dairy Heifer Evaluation Program (NDHEP) study during a violation investigation and comprised the case group. The controls were the 51 randomly selected Washington dairies that participated in the NDHEP, completed the four NDHEP questionnaires, and had not been identified as having residue violations. Management factors investigated were those associated with maternity and pre-weaning hygiene, vaccination and preventive practices, type and management of liquid calf feed, and general management. Other factors included herd somatic cell count (SCC), the presence of clinical signs associated with diseases of body systems, and herd size. Significant associations were detected between violation occurrence and the management of calving cows, colostrum volume and management, and the person responsible for calf care. Significant associations but of the wrong direction were found between violation occurrence and type and management of liquid calf feed. No significant associations were detected between violation occurrence and the remaining management factors, herd size, animals entering the herd, or SCC.     

Development of a model for the prediction of feed intake by dairy cows: 1. Prediction of feed intake

A study was undertaken to develop a model for the prediction of dry matter intake by lactating Holstein Friesian dairy cows. To estimate the model parameters, a calibration dataset was compiled with the data from 32 feeding experiments conducted at 9 different sites. The database contained weekly information on 1507 lactating Holstein Friesian dairy cows regarding their diet composition and feed analysis, together with their individual voluntary feed intake, milk yield (MY), milk composition, parity, days in lactation and days pregnant.Dry matter intake was predicted from feed and animal characteristics. The feed chemical composition and digestibility can be related to feed degradation, bulk volume, intake rate, palatability and other factors influencing feed intake. Therefore, the data of standard feed analysis were used to estimate the satiety value of numerous commonly used feeds and forages. The satiety value is the measure of the extent to which a feed limits intake. The cows' ability to process the intake-limiting satiety value-units is expressed as the feed intake capacity, which is predicted from parity, days in milk and days of pregnancy which are indicators of the size and physiological state of the cow. This study shows that feed intake can be predicted using a limited number of easy-to-measure inputs that are available on commercial farms, yet reasonably biologically sound. Because the model inputs are not related to animal output (milk yield or body weight), future extension of the intake model with models for the prediction of animal performance is possible.     

Effect of level of milk replacer fed to Holstein calves on performance during the preweaning period and starter digestibility at weaning

Calves following an enhanced-growth feeding program usually show lower starter intakes during the preweaning period compared with conventionally-fed calves. To assess whether this low intake in calves following an enhanced-growth feeding program affects calf capacity to digest starter after weaning, 19 Holstein male calves were used to measure apparent nutrient digestibility at weaning. Calves were divided in two groups: calves on a conventional feeding program (CF) and calves on an enhanced-growth feeding program (EF). After one week of adaptation to milk replacer (25% CP and 19% fat), the CF calves were fed 4 l/d of milk replacer (MR) at 12.5% DM dilution rate from d 1–28, and 2 l/d from d 29 to weaning day at d 35, and the EF calves were offered MR at 18% DM dilution rate: 4 l/d from d 1–6, 6 l/d from d 7–13, 7 l/d from d 14–20, 6 l/d from d 21–28, and 3 l/d from d 29 to 35. Calf starter (20% CP) was offered ad libitum from the beginning to the end of study at d 42, and its consumption was recorded daily. Calves were weighed at d 3, 17, 24, 31, 38 and 42. Daily total faeces collection was conducted for the last 5 d of study. Final BW was numerically greater in EF than in CF calves (88.6 vs 81.2 ± 3.36 kg, respectively). Starter DMI was greater (P < 0.05) in CF compared with EF calves during the preweaning (0.68 vs 0.36 ± 0.078 kg/d, respectively) and postweaning (2.52 vs 1.90 ± 0.102 kg/d, respectively) periods, but there were no differences in total DMI (1.12 and 1.26 ± 0.078 kg/d, in CF and EF calves, respectively) during the preweaning period. However, apparent DM, OM, NDF, CP, and GE digestibility coefficients were greater (P < 0.05) in CF compared with EF calves (77.4 vs 71.8 ± 1.23%, 78.7 vs 73.2 ± 1.18%, 34.7 vs 20.3 ± 3.79%, 77.1 vs 71.6 ± 1.29%, and 75.6 vs 69.8 ± 1.25%, respectively) the week after weaning. It is concluded that calves in the EF treatment presented lower nutrient digestibility coefficients compared with CF calves the week after weaning.     

Effect of suckling cow's milk or milk replacer on abomasal luminal pH in dairy calves

Abomasal ulceration occurs commonly in suckling calves, and the cause for the high prevalence of abomasal ulceration is unknown. We hypothesized that diet may play a role in the etiopathogenesis of abomasal ulceration. Six male dairy calves with an abomasal body cannula suckled fresh Holstein cow's milk, all milk-protein milk replacer, or combined milk- and soy-protein milk replacer twice daily at 12% of body weight/d. Abomasal luminal pH was measured every second for 24 hours by using a miniature glass pH electrode. Mean 24-hour abomasal luminal pH for all milk-protein milk replacer (3.22) and combined milk- and soy-protein milk replacer (3.27) were similar but significantly (P < .05) higher than that for cow's milk (2.77; standard error = 0.08). Both milk-replacer formulations failed to clot after the addition of chymosin, whereas cow's milk clotted within 2 minutes. The in vitro titration curve of cow's milk and all milk-protein milk replacer were similar, but different to that of combined milk- and soy-protein milk replacer. The osmolalities of all milk-protein milk replacer (375 mOsm/kg) and combined milk- and soy-protein milk replacer (410 mOsm/kg) were greater than that of cow's milk (278 mOsm/kg). The slightly lower mean abomasal luminal pH in calves suckling cow's milk, compared to milk replacer, was probably due to clotting of cow's milk, with extrusion of low pH whey, and a slower rate of abomasal emptying caused by the hyperosmolality of milk replacer. Examination of our results suggests that suckling cow's milk may increase the prevalence of abomasal ulceration by decreasing mean luminal pH, although this remains to be determined.     

Night feeding for high-yielding dairy cows in hot weather: effects on intake, milk yield and energy expenditure

Heat load impairs the feed intake and milk yield of dairy cows: The higher their milk yield and energy expenditure (EE), the larger the expected effect. Our objective was to examine the efficacy of feeding such cows at night, which avoiding their access to feed for 5 1/2 h during the hot hours of the day, to reduce the heat load upon them in a hot climate. Approximately 120 cows in a herd in a hot region in Israel were allocated to two treatments: day (DFT) or night (NFT) feeding, which differed only in the schedule of feed allocation. The experiment was conducted from May to September 2000 (118 days). The cows were group fed on a total mixed ration, and the daily amounts of feed offered and of orts collected were recorded. The daily group average milk yield was also recorded. Ten cows in each group were selected for individual measurements. The energy expenditure of these cows was estimated once before and three times during the experiment, by monitoring heart rates and measuring oxygen consumption. The rectal temperatures and respiration rates (RR) of these cows were measured in the morning and afternoon on two consecutive days in August. Cows on NFT had lower feed intake but similar milk yield to that of DFT cows, and NFT cows had better milk yield persistence over time. The effects of the temperature-humidity index (THI) on milk yield and intake were similar in the two treatments. The rectal temperature and respiration rate, and the increase in these measures from morning to afternoon hours, did not differ from DFT and NFT cows. The energy expenditure of NFT cows was lower than that of DFT cows, and their efficiency of energy utilization for milk production was higher.     

Herd-level factors associated with isolation of Salmonella in a multi-state study of conventional and organic dairy farms II. Salmonella shedding in calves

The objective of this study was to evaluate associations between herd-level factors and the isolation of Salmonella in calves from dairy farms in Minnesota, Wisconsin, Michigan and New York. Study farms were 129 conventional and organic farms enrolled without regard to previous history of Salmonella infection. Herds were sampled at 2-month intervals over a 1-year period. Salmonella was isolated in fecal samples from 176 (3.8%) of 4673 preweaned calves with 40 (31.0%) of 129 farms having at least one positive calf sample over the course of the study. Multivariable logistic regression using the generalized estimating equations approach was used to evaluate risk factors for Salmonella shedding after adjustment for effects of herd size, season, state of origin and the multiple sampling occasions per herd. Factors retained in the final model that were associated with an increased odds for Salmonella shedding were lack of routine feeding of milk replacer containing antimicrobials to preweaned calves (OR = 2.8, 95% CI: 1.4, 5.8), use of maternity housing as a hospital area for sick cows more than once a month (OR = 2.1, 95% CI: 1.1, 4.0), and cow prevalence level by visit, categorized into the following four-levels: ≥20% (OR = 11.6, 95% CI: 5.7, 23.7), 10–19.9% (OR = 4.7, 95% CI: 2.0, 11.5), 0.1–9.9% (OR = 3.6, 95% CI: 1.5, 8.7) and 0% (reference level). Herd size was not associated with Salmonella shedding in the final multivariable model.     

应用代乳粉培育放牧犊牦牛的生长效果和经济效益分析

通过研究不同营养水平的代乳粉对48头犊牦牛生长发育的影响及对其生产经济效益的分析,发现在本试验条件下:饲喂27%、29%蛋白质水平的代乳粉对犊牦牛的增重效果优于自然放牧牦牛;饲喂29%蛋白质水平代乳品的犊牛生长性能优于饲喂25%和27%蛋白质水平代乳粉的犊牛;对犊牦牛饲喂代乳粉的经济效益大幅优于天然放牧的犊牦牛,27%蛋白质水平代乳粉的投入回报率最高。     

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.     

Feed intake and oral behaviour of dairy calves housed individually or in groups in warm or cold buildings

The influence of environmental temperature, housing, social company and age on the feed intake and oral behaviours was studied by housing male dairy calves for seven weeks individually (INDIV) or 12 weeks in groups of four; indoors (INGROUP) or outdoors either with (OUTWARM) or without a heated shelter (OUTCOLD). During the milk-feeding period (1–7 experimental weeks), the mean daily milk, hay and total dry matter intakes of INDIV calves were lower than of INGROUP calves (P < 0.05). No differences in the feed intake between OUTWARM, OUTCOLD or INGROUP were found. Nor was found any differences in the feed efficiency (growth kg^− 1 DM) between the treatments. After weaning off milk, during experimental weeks 8 to 11, the total dry matter intake of INGROUP tended to be greater than that of OUTWARM (P = 0.05). There were no other differences in the mean daily feed intakes, nor in the feed efficiency. During the milk-feeding period, INGROUP calves ate more often concentrates (P = 0.05) and ruminated more (P = 0.01) than INDIV calves. During the 12-week experiment, INGROUP calves licked themselves more often than OUTCOLD calves (P = 0.04) and tended to lick more often than OUTWARM calves (P = 0.08). INGROUP calves licked more often penmates or structures and bit more often structures than OUTWARM or OUTCOLD calves (P < 0.05 for all). Overall, with a decreasing temperature, the calves in outside groups spent less time performing oral behaviours. We conclude that group rearing may facilitate calves to start eating and ruminating earlier than individual housing. The effect of low temperatures on the time spent eating solid foods is discussed in relation to housing design.     

不同饲养模式对哺乳犊牛消化道形态学结构的影响

为了研究不同饲养模式对犊牛消化道形态学结构的影响,试验选择20头体重相近的荷斯坦哺乳犊牛,采用完全随机试验设计,将犊牛分为2组,分别为对照组和试验组,对照组喂颗粒精料+牛奶,试验组饲喂颗粒精料+牛奶+优质牧草。结果表明:对照组犊牛瘤胃乳头数量和长度显著高于试验组(P<0.05),瘤胃厚度低于试验组(P<0.05)。说明添加牛奶和精料可以促进犊牛的瘤胃乳头发育,而添加牛奶、精料和干草则可促进瘤胃容积和组织的发育。     

液态饲料饲喂量对0～2月龄犊牛生长性能的影响

本试验旨在研究液态饲料的饲喂量对犊牛生长性能及健康情况的影响。选取24头新生荷斯坦犊牛,随机分为3个处理,每个处理8个重复,每个重复1头牛,分别按照体重的9.5%、11.0%、12.5%饲喂代乳品乳液。试验全期为8周。测定犊牛的体尺、体重、采食量和记录粪便评分。结果显示:3组犊牛的采食量差异显著(P<0.05)。在日增重上,9.5%组的犊牛比11.0%组和12.5%组的犊牛低(P>0.05),且在3~4周龄时,表现出显著性差异(P<0.05)。在饲料转化率上,3组犊牛在0~6周龄内均不断改善,其中3~4周龄时11.0%组优于9.5%组和12.5%组(P<0.05)。3组犊牛的粪便指数均较低,但在添加开食料和羊草时,有所波动。在单笼饲养条件下,液态饲料中干物质占12.5%时,按犊牛体重的11.0%饲喂液态饲料可获得最佳生长性能。     

Nitrogen efficiency of dairy cows as affected by diet and milk yield

The aim of this study, which was part of the EU-financed project Life Ammonia, was to evaluate the effects of dietary components and milk production on nitrogen efficiency of dairy cows. The study included examining the effects of decreased crude protein (CP) concentration in a grass-clover silage based diet and results of mixing whole-crop barley silage (WCBS) with grass-clover silage in the diet, on feed intake, milk production and nitrogen efficiency. Rations were formulated and milk production data were registered individually each month for 42 cows of the Swedish Red Cattle breed during four indoor periods from 1999 to 2003. The range in nitrogen efficiency by the cows, 11 to 398 days in milk, was 18 to 40%, when fed a diet containing 135 to 184 g CP/kg DM, 44 to 56% of NDF as rumen degradable fibre (RDF) and milking 13 to 57 kg of ECM daily. The average CP concentration of the diet, containing mainly grass-clover silage and concentrate, was decreased from 168 g/kg DM (170 g in early lactation) in the control treatment period to 160 g/kg DM (163 g in early lactation) during the following treatment period. The CP concentration was 170 g/kg DM (171 g in early lactation) during the third treatment period, when the grass-clover silage was fed in a mixture with WCBS. Using the whole data set (n = 284 for primiparous, n = 440 for multiparous cows based on measurements each month) resulted in models, in which total DM intake, ECM yield, dietary CP concentration and RDF were the most important factors affecting nitrogen utilisation of primiparous and multiparous cows. Increases in both average DM intake and milk yield by multiparous cows and no changes in average intake and milk yield by primiparous cows fed the low CP diet or the normal CP diet containing WCBS, compared to cows fed the normal CP diet, resulted in similar nitrogen efficiencies among the treatments. Hence, dietary CP concentrations of 160 to 170 g/kg DM can be used for cows in early lactation in commercial herds to improve nitrogen utilisation without causing a simultaneous decrease in milk yield.     

Effects of parenteral supply of iron and copper on hematology, weight gain, and health in neonatal dairy calves

The objective of the present study was to examine the effects of parenteral administration of iron and copper on hematological parameters, weight gain, and health of neonatal dairy calves in the period when iron and copper deficiency could be existed. Twenty-four Holstein calves were used for the experiment and randomly assigned to four different treatments. Treatments consisted of (1) control (no injections of Fe and Cu), (2) test 1 (1000 mg Fe as fe-dextran was injected to each calf at day 2 of age), (3) test 2 (160 mg Cu as methionine-copper complex was injected to each calf at day 14 of age), and (4) test 3 (Fe and Cu were injected to each calf as mentioned previously). Blood samples were collected from all of the calves within 24-48 hours after birth and at 7, 14, 21 and 28 days of age for measuring hematological parameters and within 24-48 hours after birth and at 14, 21 and 28 days of age for the determination of iron, copper, TIBC concentrations, and AST activity. Anti-coagulated blood was analyzed shortly after collection for: number of red blood cell (RBC), hemoglobin (Hb), heamatocrit (HCT), total leukocyte count (WBC), Platelet (Plt), MCH, MCV, MCHC, and differential leukocyte counts. The amounts of iron, copper, TIBC, and AST were measured in serum. Group had significant effects on the amounts of HCT, RBC, hemoglobin, MCV, neutrophil, weekly weight gain, and daily gain during each week (p < 0.05). Sampling time had significant effects on the amounts of RBC, MCV, MCH, MCHC, WBC, neutrophil, lymphocyte, monocyte, platelet, fibrinogen, copper, TIBC, AST, weight, weekly gain and, daily gain during each week (p < 0.05). significant interactions between sampling time and group were seen for HCT, RBC, hemoglobin, MCV, platelet, total protein, fibrinogen, iron, and TIBC (p < 0.05). Improved RBC parameters and MCV were seen in calves of group 4 (test 3) in comparing with control group. Total and daily gains were also significantly improved in test groups in comparing with control group (p < 0.05). No significant difference was seen for the days of treatment between groups.