Growth studies of bulls of black-and-white dairy cattle during low feed levels. 4. Derivation of energy requirements

On the basis of two long-term individual feeding experiments the growth-related energy requirement values for low live weight gains (500, 600 and 700 g daily cumulative live weight gain per animal derived by Pieper et al. in 1984 (1984b) were ascertained more precisely. The differences from the recommendations of the GDR feed evaluation system found earlier (Pieper et al. 1984) were confirmed. In general one can say that the differentiation of energy requirement in dependence of live weight gain with live weight being equal is greater than according to the GDR feed evaluation system (1986). Under consideration of a norm factor of 1.05 this results in the live weight range of between 50 and 500 kg and with a cumulative live weight gain of 500 g/animal and day in an energy expenditure of 4.44 kEFUcattle/kg live weight gain, of 600 g/animal and day i an energy expenditure of 4.08 kEFUcattle/kg live weight gain and of 700 g/animal and day in an energy expenditure of 3.82 kEFUcattle/ kg live weight gain.     

Growth studies of bulls of the black pied dairy cattle breed during low feed levels. 3. Anabolism and energy metabolism at empty body weight at slaughter

In two long-term individual feeding experiments with rations very rich in roughage, nutrient and energy retention in the course of live weight development of black-and-white dairy bulls were determined. For this purpose, a total of 123 animals were slaughtered at the age of 5, 9, 12, 15, 18, 21 and 24 months, and the total body was analysed of 97 animals. The ascertained protein, fat and energy retention per day showed a clear dependence of the implemented level of nutrition. The results received compare well with the findings of earlier studies (PIEPER et al., 1984a). At a nutrition level (maintenance = 1.0) of 1.38 = 473 g gain of empty body [table: see text] at a nutrition level of 1.48 [context: see table] live weight range between 150 and 450 kg. The dynamics of the nutrient and energy retention in the course of live weight development is depicted in tables.     

饲养模式对科尔沁肉牛育肥性能的影响

[目的]为研究饲养模式对科尔沁肉牛育肥性能的影响,特开展本试验研究,以期为农牧民提供饲养育肥牛的技术指导。[方法]选取体重体型均等的科尔沁肉牛架子牛120头,随机分为试验组1、试验组2与对照组,每组各40头。试验组1根据资料与经验制定为期185 d的饲养方案1,试验组2对养殖户自有饲养模式的饲料量与精粗配比优化后制定为期245 d的饲养方案2,对照组按照养殖户以往模式进行饲养,育肥期结束后称量体重,计算各组日增重数据。[结果]结果显示,试验组2的增重比试验组1与对照组分别提高37.2%与6.4%;试验组2与对照组的饲料利用率显著低于试验组1;经济效益方面试验组2的效益高于试验组1与对照组。结果表明试验组2为较合适的育肥牛饲养模式。[结论]试验证明,制定科学、系统的饲养模式,以合理的育肥时长、饲料摄入及精心的饲养管理,能够提高科尔沁肉牛育肥牛的育肥性能并获得更高的经济效益。     

The relationship between feeding and fertility in dairy cattle]

The possible relationship between nutrition and fertility in dairy cows are reviewed. Study of the literature shows that opinions on the effect of the various nutrients differ markedly. The conclusion which can be made is that in countries where standards of dairy farming are high, nutrition only plays a minor role in the problem of herd subfertility. In the course of time deficiencies in a large number of minerals, trace elements and vitamins have been stressed as a cause of inadequate fertility. However cows are at present generally fed with a lot of well balanced concentrates and therefore deficiencies are very unlikely to occur. During early lactation every high producing dairy cow has a negative energy balance. In a number of cows this results in anoestrus and in a long interval from parturition to first insemination. Overfeeding during late lactation and the dry period does not adversely affect subsequent reproduction but may cause puerperal disorders. The relation between protein nutrition and fertility is complex. Protein effects on fertility are minor. Problems can arise if there is a combination of a high percentage of crude protein (greater than 18%), a high rumen degradability of the protein and a low energy content of the diet. The value of metabolic profile tests is minimal because they do not differentiate between normal herds and herds with fertility problems.     

Growth, slaughter performance and feeding behaviour of young bulls belonging to three native cattle breeds raised in the Alps

Most studies on lactation curves only consider milk yield and describe a standard lactation curve of dairy cows, showing a peak or maximum daily yield occurring between 4 and 8 weeks after calving, followed by a daily decrease in milk yield until the cow is dried off. Wood's model is a widely used lactation curve function. Wood's model was fitted to test-day records of 95,405 lactations of parities lower than 5. Milk traits were milk yield (MY), fat percentage (F%), protein percentage (P%), fat yield (FY) and protein yield (PY), and the lactation curve was individually considered as a cluster of five linked curves. Milk trait and parity influence the goodness of fit of Wood's model. In 19.3% of the lactations, the shape of the MY, FY and PY curves follows the standard lactation curve while F% and P% have the reversed standard shape. The initial phase of lactation with the FY and PY curves contributes to the high variability of shapes.     

Productive performance of the dairy cattle Girolando breed mediated by the fat-related genes DGAT1 and LEP and their polymorphisms

Candidate genes have been associated with milk production in bovines, such as the diacylglycerol O-acyltransferase 1 (DGAT1) and leptin (LEP); however, they have not been simultaneously investigated nor have been evaluated in the Brazilian Girolando breed (Gir × Holstein, backcrossed to Holstein). Our aim was to determine the influence of fat-related genes, DGAT1 and LEP, and their polymorphisms on performance traits of milk production in the Girolando breed. Results indicated that the K allele of the DGAT1 gene showed a significant association with total and average daily milk production with additive effect. The LEP gene showed that the A allele and its homozygote are highly prevalent and almost fixed in this population and may have been favorably selected during backcrossing for the origin of this breed. The important impact of the K allele of the DGAT1 gene on milk production corroborates the initiative of performing marker-assisted selections with this gene in breeding programs of the Girolando breed.     

Productive performance of the dairy cattle Girolando breed mediated by the fat-related genes DGAT1 and LEP and their polymorphisms

Candidate genes have been associated with milk production in bovines, such as the diacylglycerol O-acyltransferase 1 (DGAT1) and leptin (LEP); however, they have not been simultaneously investigated nor have been evaluated in the Brazilian Girolando breed (Gir × Holstein, backcrossed to Holstein). Our aim was to determine the influence of fat-related genes, DGAT1 and LEP, and their polymorphisms on performance traits of milk production in the Girolando breed. Results indicated that the K allele of the DGAT1 gene showed a significant association with total and average daily milk production with additive effect. The LEP gene showed that the A allele and its homozygote are highly prevalent and almost fixed in this population and may have been favorably selected during backcrossing for the origin of this breed. The important impact of the K allele of the DGAT1 gene on milk production corroborates the initiative of performing marker-assisted selections with this gene in breeding programs of the Girolando breed.     

Histological studies on the hypothalamic adenohypophyseal-gonadal system after mestranol and chlormadinone acetate administration in fattening bulls]

Seventy-six young steers were examined to elucidate the action of the steroid oestrogen Mestranol and the gestagen chloromadinone acetate upon the morphology of hypothalamus, adenohypophysis, testes, and accessory sexual glands. The doses used were those applicable also to real animal husbandry. The mechanisms of action of the above pharmaceutical products are discussed against the background of the experimental results. No pathological alteration was observed that might prohibit application of the tested sexual steroids to young steers.     

Investigations concerning the use of the rumen fermentation regulator monensin in feeding fattening bulls

In two digestion experiments with wethers and seven feeding experiments with 198 fattening bulls with rations rich in (greater than 55% of the dry matter intake from roughage), the influence of the antibiotic monensin on the digestibility of the ration, on rumen-physiologic characteristic values and on fattening and slaughtering results was investigated. The digestibility of the organic matter and the crude nutrients was not significantly influenced by the use of monensin (20 mg/kg dry matter). The administration of 200 mg monensin per fattening bull and day resulted in an increase of the molar concentration of propionate in the rumen fluid by 9.7 mol%, the concentration of acetate and butyrate decreased by 7.3 resp. 2.8 mol %. On an average of the seven experiments the intake of dry matter was diminished by 5.1% through the use of monensin, the live weight increase remained almost unaffected (3.0% additional increase), feed and energy requirement per kg live weight were improved by 7.9%. The fattening results do not always correspond in the various experiments. The results of the dressing of the carcass, the composition of the carcass and the quality of the meat remained unaffected by the administration of monensin.     

Growth studies of SMR bulls under different feeding conditions. 4. Nutrient and energy retention in the body

In long-term feeding experiments with bulls of the species Holstein-Friesians, the relation between live weight development and nutrient and energy retention was investigated on a high, medium and low level of feeding intensity. For this purpose a total of 206 animals was butchered at the ages 0, 4, 9, 12, 15, 16.5 and 18 months and the complete bodies were analysed. This showed that fat retention was considerably more influenced by the feeding intensity than protein retention. On the basis of the same body weight the energy content per kg live weight gain is not constant but increases with the growing feeding intensity.     

Subacute butyric acid burden in cattle. 1. Clinical results and effects on the carbohydrate-fat metabolism and the liver function of young fattening bulls

Daily butyric acid doses of 0.5 g/kg body weight or 1.0 g/kg were intraruminally applied to 8 young fattening bulls together with regular feed rations, for 19 days, following an initial phase for adaptation. Indigestion phenomena were recordable from 30% of the animals, primarily on the early days of the experiment. Both doses produced sinusoidal beta-OH butyrate curves without major dose-dependent deviations. The concentrations of glucose and free fatty acids were indicative of temporary subclinical ketosis. Neither ASAT, ALAT, and gamma-glutamyltransferase nor bilirubin nor liver glycogen were indicative of liver damage. The lower dose of 0.5 g/kg was widely tolerated, but clearly discernible disorders developed in response to the higher dose of 1.0 g/kg of butyric acid.     

Constraints on dairy cattle productivity at the smallholder level in the Philippines

Survey data on dairy cattle production were gathered in two sites [Site I (three-year survey) and Site II (two-year survey)] in Southern Luzon, Philippines. Crossbred (Holstein-Friesian x Sahiwal) dairy cows (n = 122) managed by smallholder farmers belonging to five primary cooperatives under the federation of dairy farmers, were monitored monthly for milk production, feed intake and availability, and reproduction and health status. The purpose of the survey was to identify constraints to productivity. The reproductive status of the cows was monitored by measuring milk and plasma progesterone concentrations by radioimmunoassay and rectal palpation of the ovaries. Plasma concentrations of selected metabolites [beta-hydroxybutyrate (BHB), inorganic phosphorus, albumin, globulin, urea] were also measured at one month before calving and at one month and 2-3 months postpartum, to determine if these could serve as biochemical indicators of nutritional stress. A long calving interval (CI = > 400 days) was identified as the major constraint to productivity of dairy cattle on smallholder farms. The three main problems related to this reproductive constraint were: (1) poor breeding management, in particular lack of accurate estrus detection; (2) repeat breeding, i.e. three or more services were required before conception; and (3) poor ovarian function, shown by some cows with lose progesterone levels. An important cause of these problems was undernutrition, particularly at critical periods of the cow's reproductive life, reflected in the slow recovery from loss in body weight and condition score during the early postpartum period and the increased plasma BHB values at peripartum period in some cows, indicative of negative energy balance, and the flat lactation profile. These findings are useful and relevant as a database in the development of an appropriate management scheme aimed toward improving dairy cattle production and productivity at smallholder level. It highlights the importance of estrus detection, good breeding management and the use of a practical strategic nutritional supplementation, particularly during stressful periods in the cows's reproductive life.     

Subacute butyric acid burden in cattle. 2. Effect on the acid-base balance and the protein metabolism in young fattening bulls

Three weeks of butyric acid applications (0.5 g/kg and 1.0 g/kg body weight) caused strong dose-dependent strains on the acid-base balance in young fattening bulls aged 4 months. Disorders were primarily reflected in changed net values of acid-base excretion in urine. Activity of alkaline phosphatase was found to depend strongly and directly on these changes. Drastic variations were recorded also from nitrogen metabolism.     

Economic aspects of reproductive failure in dairy cattle. I. Financial loss at farm level

Some years ago, systematic research was initiated to improve quantitative insight into the economic impact of diseases and disease control in livestock. This paper deals with the financial loss at farm level caused by reproductive failure in dairy cattle. Economic calculations concerning the calving interval of cows which differ in age, relative production level and persistence of milk production during lactation were made. On average, an optimal interval of 1 year or less was established, while the loss per day lengthening of the interval (norm-loss) amounted to 1–2 Dutch guilders (Dfl.). Also, 676 norm-losses due to forced replacement because of reproductive failure were determined, dependent on age and relative production level of the culled cow and average herd life of the farm. On average, this norm-loss was determined to be almost Dfl. 500 per culled cow. Based on 71 farms in an investigation in the province of Overijssel, total loss per farm was determined, using the calving interval data, forced replacement data and norm-loss rate described above. On average, the calculated loss amounted to Dfl. 63 per cow per year, of which Dfl. 35.50 resulted from sub-optimal calving interval and Dfl. 27.50 from forced replacement due to reproductive failure. Costs for veterinary treatment and drugs were not included in these elements. Total loss due to reproductive failure was estimated to average about Dfl. 80 per cow per year, which equals about 2% of the gross production value or 10% of an average farmer's income.Finally, considerable differences in loss between farms have been determined. The difference between the 20% of farms with the highest and the 20% of farms with the lowest calculated loss is even more than the average loss. Thus improvment may be achieved on many farms, e.g., with the help of a herd health programme.     

Plasma leptin concentration in adult cattle: effects of breed,adiposity, feeding level,and meal intake

An ovine-specific RIA, shown to be reliable for bovine leptin determination, was used to study the effects of breed, body fatness, feeding level, and meal intake on plasma leptin level in adult cattle. Eighteen fat Charolais, fat Holstein, and lean Holstein adult cows were either well-fed (130% of maintenance energy requirements [MER]) or underfed (60% of MER) for 3 wk. The breed tended to have a small effect on plasma leptin level, which was decreased by 70% (P < 0.05) in lean compared to fat Holstein cows. A strong curvilinear relationship was found between mean adipocyte volume and plasma leptin concentrations in well-fed (r = +0.95) and underfed (r = +0.91) cows. Underfeeding caused a significant decrease in plasma leptin levels from 8.0+/-3.1 to 6.1+/-2.3 ng/mL (P < 0.01). Nine adult Holstein cows initially fed at 130% of MER (control) were underfed to 21% of MER for 7 d, and five of them were refed to 237% of MER for 21 d. Plasma leptin measured 1 h before meal distribution was decreased from 5.9+/-0.4 to 3.8+/-0.2 ng/mL (P < 0.01) by underfeeding and increased to reach 8.8+/-1.0 ng/mL (P < 0.01) after refeeding. It was positively related to plasma glucose (r = +0.52, P < 0.01) and negatively related to plasma NEFA (r = -0.67, P < 0.001). Plasma leptin measured 4 h after meal distribution was positively related to feeding level and to plasma 3-OH-butyrate (r = +0.61, P < 0.005) and negatively related to plasma NEFA (r = -0.56, P < 0.01). Differences between pre- and postprandial leptin concentrations showed a decrease after meal intake in control and well-fed cows (-7 and -19%, P < 0.01, respectively) and an increase in underfed cows (+12%, P < 0.01). Leptin response to meal intake was positively related to glucose response (r = +0.66, P < 0.001) and negatively related to 3-OH-butyrate response (r = -0.78, P < 0.001). By using the "multispecies" commercial RIA, leptin concentrations were lower and we observed similar physiological responses, although less related to other hormones or metabolites. These data provide evidence, first, that a specific RIA for ruminant leptin determination is necessary to better understand leptin regulation, and second, that plasma leptin is strongly related to adipose cell size and positively related to feeding level in adult cattle, and that an effect of meal intake could be mediated by glucose and(or) ketone bodies.     

陕西奶牛良繁改良成效及对策建议

[摘要] 奶业发展,种业先行。良种是奶业产业链的源头和支柱,决定着奶牛产业发展的质量和效益。陕西作为全国重要的奶牛、奶山羊“双奶源”基地,具有做强奶业的基础和优势,尤其是奶牛产业,更是要做好奶牛育种工作。本文围绕调研繁殖发展数据,从奶牛良种繁育发展成效、存在问题等方面进行分析,提出对策建议,助推奶牛产业高质量发展。