Effects of sodium monensin on reproductive performance of dairy cattle. II. Effects on metabolites in plasma, resumption of ovarian cyclicity and oestrus in lactating cows

SUMMARY A randomised trial was conducted to determine the effects of sodium monensin on plasma metabolite concentrations, resumption of cyclicity and oestrus and milk production and milk composition of postparturient dairy cows. Cows treated with sodium monensin in a controlled-release capsule had significantly lower plasma β-hydroxybutyrate (BHB) concentrations (P = 0.006) and tended (P = 0.07) to have significantly higher plasma glucose concentrations than untreated cows. Treatment did not significantly influence plasma free fatty acid, urea nitrogen or cholesterol concentrations. Despite higher plasma glucose concentrations and lower plasma BHB concentrations, periods from calving to first ovulation and oestrus were not reduced by treatment. This observation, with limited numbers of cows, is not consistent with a hypothesis that glucose or ketones are important metabolic regulators of pulsatile release of luteinising hormone and consequent resumption of cyclicity. While milk production and milk protein concentration did not significantly differ between groups, milk fat concentration was significantly lower for treated cows. Treated cows probably had lower dry matter intake than untreated cows as they produced 67 litres less milk per head and lost more weight than untreated cows during the study period, although weight and body condition score were not significantly affected by treatment. The lack of significance of these latter observations probably reflects the low statistical power of the study.     

过瘤胃保护蛋氨酸对奶牛乳和血浆氨基酸含量及血液生化指标的影响

本研究采用在生产条件下的对比饲养试验,通过研究日粮中添加本实验室研发的过瘤胃保护蛋氨酸产品对高产荷斯坦牛乳和血浆氨基酸含量与组成、血液生化指标的影响,验证产品的性能,探讨过瘤胃保护蛋氨酸对奶牛生产性能和乳成分产生影响的机理。试验选择2～5胎之间、日产奶量30kg以上、处于泌乳高峰期的荷斯坦牛20头,随机分为两组,试验组每头每天添加本实验室研发的过瘤胃保护蛋氨酸产品75g。试验结果表明,日粮中添加该产品可明显增加荷斯坦牛乳大多数种类氨基酸和总氨基酸含量,使11种血浆游离氨基酸含量有不同程度的增加,总游离氨基酸含量有一定程度的提高,血浆白蛋白、球蛋白、总蛋白含量明显增加,6种血浆游离氨基酸含量有不同程度的降低,谷草转氨酶和谷丙转氨酶活性增强,游离脂肪酸含量和葡萄糖含量明显上升,尿素氮含量明显降低。上述结果进一步验证了本实验室研发的过瘤胃保护蛋氨酸产品具备较好的瘤胃稳定性和小肠可消化性,在一定程度上揭示了其提高产奶量和乳蛋白含量的作用机理。     

Amino acid utilisation by dairy cows. II. Concept of amino acid requirementsUtilisation des acides aminés par les vaches laitières. II. Concept des besoins en acides aminésAminosäureverwertung bei milchkühen. II. Zum konzept des aminosäurenbedarfs

In dairy cows amino acids may be required for four processes: maintenance; as precursors for the synthesis of glucose (gluconeogenesis); for protein deposition in muscle or associated with foetal growth; and for the synthesis of milk protein.Estimates of the protein requirements for maintenance are often conflicting and seem far from accurate. Estimates of the ratio in which essential amino acids are required for maintenance are not yet available.Requirements of amino acids for gluconeogenesis are difficult to estimate. It seems rather unlikely that essential amino acids will be used in significant quantities for gluconeogenesis, even at high milk yields.Protein requirements for pregnancy and muscle growth in dairy cows are relatively low. The ratio in which essential amino acids are supplied in the blood seems adequate for both processes.Amino acid requirements for milk protein synthesis are somewhat higher than the net protein output. This is particularly true for essential amino acids of which, in the mammary gland, a surplus of some 50% needs to be extracted from the blood. The ratio in which essential amino acids are supplied to the mammary gland seems reasonably adequate for milk protein synthesis.     

保护性蛋氨酸与赖氨酸在奶牛生产中的应用

乳蛋白是体现牛奶质量的重要指标,乳蛋白氨基酸来源于日粮氨基酸。乳蛋白中酪蛋白、乳白蛋白和乳球蛋白除了满足人体基本营养需求,还对人体生长、发育和健康发挥重要作用,是动物源优质蛋白质来源。蛋氨酸与赖氨酸是奶牛日粮限制性氨基酸,不仅是乳蛋白合成的重要底物,同时还作为信号分子调控乳蛋白基因表达。本文综述了奶牛氨基酸需要与来源、必需氨基酸、限制性氨基酸、保护性蛋氨酸和赖氨酸在日粮中的应用,阐述了氨基酸营养在蛋白质合成代谢中的核心作用,为指导奶牛日粮配方提供参考。     

Plasma amino acid pattern during the first month of life in calves fed the first colostrum at 0-2 h or at 24-25 h after birth

Calves are born with a mostly inadequate essential amino acid (EAA) status. Studies were designed to test the hypothesis that delaying the intake of the first colostrum for 24 h, besides its early effects, also has late effects on plasma free amino acid levels and on the protein status. There were marked and rapid elevations (within 2 h) of plasma levels of various amino acids, and especially of EAA, after the intake of the first colostrum, whereas changes after the intake of mature milk on day 28 of life were mostly absent or concentrations even decreased. The EAA and non-essential amino acid (NEAA) status was rapidly normalized after intake of the first colostrum, but normal plasma levels of some amino acids were also reached during the first 24 h of life even when the first meal was withheld. Delaying colostrum intake had only transient effects on EAA and NEAA (except hydroxyproline), in contrast to its effects on plasma immunoglobulin G and total protein levels.     

Studies on parturient paresis in dairy cows. V. On the composition and calcium binding capacity of two bovine serum protein fractions, with special regard to parturient paresis

In healthy cows unaffected by imminent or recent calving the protein in serum can directly bind the overwhelming proportion of the bound calcium. In recent calvers this capacity is considerably less. When adding ammonium sulphate to blood serum to 62 % of total saturation a protein fraction precipitates which is mainly albumin. This fraction has a far greater calcium binding capacity than the soluble fraction, which contains most of the serum globulin, and the lowering of this capacity after calving is entirely referable to the former fraction. No difference has been found in these respects between normal cows after calving and cows with parturient paresis.An analysis of 10 amino acids in the two protein fractions described above showed that the amino acid composition of both exhibits differences between recent calvers and cows outside the calving period, and likewise that each of the two fractions differs in composition between healthy cows after calving and cows with parturient paresis.     

Research Progress on Milk Protein Synthesis Regulated by Amino Acids in the Mammary Gland and Its Molecular Mechanism in Dairy Cows

Milk proteins have great nutritional value,rich contain and balanced profile of amino acid,which provide nearly all the essential amino acids for the human body.However more than 90% of milk proteins are synthesed by the amino acids in the mammary gland.Furthermore,the amino acid is not only funcion as the substrates of milk protein synthesis,but also as the signaling molecules to regulate milk protein sysnthesis through mammalian target of rapamycin (mTOR) signaling pathways.It is essential to further study milk protein synthesis regulated by amino acids in the mammary gland and the molecular mechanism in dairy cows.The paper reviewed the supply of amino acids,metabolism of amino acids by mammary gland,factors affecting amino acid utilization and signal pathway for amino acid regulation in milk protein synthesis.     

氨基酸对奶牛乳腺蛋白质合成调控及其分子机制的研究进展

乳蛋白中含有大量人体所需的必需氨基酸,其组成平衡、含量丰富,是一种具有极高营养价值的蛋白质,而乳中 90%以上的蛋白质是乳腺利用氨基酸从头合成的,因此氨基酸对奶牛乳蛋白合成发挥着重要的作用。此外,氨基酸不仅是合成乳蛋白不可或缺的前体物质,而且还是重要的信号调控因子,通过哺乳动物雷帕霉素靶蛋白（mTOR） 信号通路调控乳蛋白的合成。基于此,作者就影响奶牛乳腺氨基酸供应、摄取、利用的因素及氨基酸的信号传导作用的研究进展进行综述,以期为提高乳蛋白的合成提供一定的理论基础。     

Effect of concentrate crude protein level on grass silage intake, milk yield and nutrient utilisation by dairy cows in early lactation.

Twenty-one multiparous dairy cows were fed concentrates containing three levels (119, 154 and 191 g/kg DM) of crude protein (CP) during the first ten weeks of lactation. Part of the grain and molassed sugar beat pulp was substituted with 0% (RSM0), 15% (RSM15) or 30% (RSM30) repeseed meal. Wilted grass silage was fed ad libitum after calving. The average response between RSM0 and RSM15 was +1.66 kg milk/d per percentage unit change in concentrate CP content. No further response occurred between RSM15 and RSM30. The positive effect of RSM inclusion was seen throughout the experimental period and was associated with increased plasma non esterified fatty acids (NEFA) and decreased plasma insulin concentration one week after calving, and higher efficiency of metabolisable energy utilisation for milk production. Digestibility of the diet remained unaffected. Milk and plasma urea tended to increase with RSM30 indicating excessive supply of rumen degradable protein. Because of the limited potential of cows to compensate for a deficit in feed protein supply by mobilising tissue protein, a substantial milk yield response can be achieved with a moderate level of protein supplementation during early lactation.     

Effects of nutritional status on hormone concentrations of the somatotropin axis and metabolites in plasma and colostrum of Japanese Black cows

We aimed to determine the effects of nutritional status on concentrations of somatotropic axis hormones (growth hormone (GH) and insulin‐like growth factor 1 (IGF‐1)), insulin and metabolites (glucose, total protein and nonesterified fatty acids (NEFA)) in the plasma and colostrum in late antepartum cows. Eight pregnant Japanese Black cows were randomly assigned to two experimental groups (n = 4 per group). Control cows (CON) received 100% of their nutritional requirements until parturition, whereas restricted group cows (RES) received 60% of their nutritional requirements. Blood samples were taken during the antepartum period, and blood and colostrum samples were collected on days 0, 1, and 3 after calving. Compared to the CON group, the RES group had higher concentrations of GH and NEFA in plasma, but significantly lower concentrations of glucose and insulin in plasma. The concentrations of GH in plasma after calving were significantly higher, but total plasma protein was significantly lower in RES than in CON cows. Compared to the CON group, the RES group had significantly higher concentrations of GH in colostrum, but significantly lower total concentrations of protein in colostrum. Concentrations of IGF‐1 were not different between the two groups. These findings suggest that maternal nutritional status during late gestation influences concentrations of GH and total protein in the blood and colostrum of Japanese Black cows.     

Effects of rumen-protected methionine in a low protein ration on metabolic traits and performance of early lactating cows as opposed to rations with elevated crude protein content

A 5‐week experiment with 24 multiparous early lactating Brown Swiss cows was conducted to investigate the effects of supplementary rumen‐protected methionine in conjunction with dietary protein reduction on metabolism and performance after 1 week of control measurement. Three rations containing 175, 150 and 125 g of crude protein/kg feed dry matter were supplemented with methionine. The fourth ration, also only containing 125 g of crude protein/kg dry matter, remained unsupplemented. The four treatment groups had a similar metabolic supply of other essential amino acids, protein and energy, as calculated by various approaches. The two low protein rations were, however, slightly deficient in ruminally degraded protein. Treatment effects remained low on feed intake, forage meal pattern, milk yield and fat as well as lactose content. In contrast, the content and yield of milk protein significantly declined only in the unsupplemented low protein ration relative to the initial value. Compared with this ration, the decline in milk protein yield was clearly delayed in the supplemented low protein ration. Blood plasma methionine tended to be reduced without supplementation and to be increased with additional methionine. Supplementation of methionine reduced other plasma amino acids. Plasma insulin, glucose, lactate, ketone bodies and aspartate amino transferase activity indicated a certain liver stress and a somewhat elevated energy requirement with high and particularly with low protein content (when unsupplemented). Methionine improved metabolic protein utilization, followed by the lowest plasma, urine and milk urea levels in the supplemented low protein diet. In conclusion, no major adverse effects were assessed under the conditions tested. Supplementation of methionine may nevertheless be useful in rations with particularly low protein content fed to early lactating cows in order to prevent negative long‐term effects which were only visible here as trends.     

Effects of peripartum biotin supplementation of dairy cows on milk production and milk composition with emphasis on fatty acids profile

Forty Holstein dairy cows receiving a 38% concentrate diet based on maize silage were assigned to either a control group, either a biotin group, receiving 20 mg of biotin per day from 15 days before expected calving date and for 120 days after calving. Milk production was measured daily, milk fat content, protein content, urea and somatic cell counts were determined weekly from week 2 to week 17 of lactation. The profile of milk fatty acids was determined at weeks 3 and 10. Plasma glucose and blood beta-hydroxybutyrate were determined before calving and at weeks 1, 2, 3, 5, 7 and 10 of lactation.

Biotin supplementation resulted in an increased milk production in multiparous cows during weeks 2 to 6, but the effect was no more significant between 7 and 17 weeks of lactation. Milk protein percent was decreased by 0.1% in multiparous cows. Milk fat content was not affected by biotin, and milk fat daily production tended to increase during early lactation. In milk fat, biotin supplementation tended to decrease the proportion of fatty acids with less than 16 carbons at week 3, but the daily amount was not affected. Biotin tended to decrease biohydrogenation intermediates, increased C16:1 at week 3, and tended to increase cis-9 C18:1 at weeks 3 and 10. After 7 weeks of lactation, biotin tended to increase blood beta-hydroxybutyrate in multiparous cows with values remaining in a normal range, and decreased plasma glucose in primiparous cows. These modifications of plasma parameters, milk protein content and profile of milk fatty acids could be due to a higher lipid mobilisation from adipose tissue driven by the increased milk production.     

能量平衡对围产期奶牛泌乳和干物质摄入量及机体代谢的影响

为了阐明不同能量平衡状况的围产期奶牛泌乳量、干物质摄入的变化及其机体代谢调节作用。在某一集约化牛场选取胎次、年龄相近的奶牛,分为高血糖组(H)和低血糖组(L),每组各15头。在产前21、14、7d和分娩当天,产后7、14、21d,分别记录奶牛围产期干物质摄入量(DMI)、泌乳量(MY),并测定血浆血糖(Glu)、游离脂肪酸(NEFA)、β-羟丁酸(BHBA)、胰岛素(Ins)、胰高血糖素(Gn)、瘦蛋白(Lp)、皮质醇(Cor)的浓度。结果显示,试验奶牛产后泌乳量和干物质摄入量均增加,但是产后能量负平衡发生率高于产前,产后21d达最高;两组产后血浆Glu水平均降低,血浆NEFA和BHBA升高,L组血浆NEFA和BH-BA水平高于H组(P0.05);H组血浆Ins与Lp水平高于L组(P0.05),血浆Gn与Cor水平低于L组(P0.05)。围产期不同能量平衡状态的奶牛机体能量代谢发生了各自适应性的变化。血浆低水平Ins、Lp和高水平Cor在缓解能量负平衡方面发挥了重要作用。     

Influence of the composition of the ration and the feeding frequency on ph-regulation in the rumen and on feed in-take in ruminants

The author illustrates that a certain ratio between roughage and concentrates in the rations of dairy cows is necessary rather than depending exclusively on an increase of the amounts of concentrates for meeting the energy requirements at higher levels of production. In general, when lactation performance is high, merely the essential supply of concentrates entails a decrease of milk fat content, or, with an insufficient energy supply, the milk protein content drops. These relations are explained by a diagram on protein fermentation and bacterial protein synthesis.Higher feeding frequency allows higher intake of concentrates without a decrease of pH in the rumen. Hence the ratio of C₂:C₃ (acetic: propionic acid) in the rumen tends towards 3:1 instead of lower ratios, which prevents a decrease of milk fat content. The higher cellulolytic activity at the higher pH leads to higher intake of roughage. With automated systems for higher feeding frequencies it will be possible to increase milk production without decrease of milk fat content and other metabolic disorders. The better energy supply will lead to a better supply of microbial protein as well and therefore prevent a decrease in milk protein content.     

Influence of zeolite A supplementation during the dry period of dairy cows on feed intake, on the macro and trace element metabolism around calving and milk yield in the following lactation

The object of the present study was to determine the influence of zeolite A, a calcium binder from the group of the aluminosilicate, on feed intake, macro and trace element metabolism as well as the milk yield in the following lactation in dairy cows. 46 cows were allotted to 2 groups (A--control group and B--experimental group). They were fed a total mixed ration (TMR) ad libitum 2 weeks before calving. Additionally the cows in group B received 90 g zeolite A/kg dry matter (DM). The individually feed intake was registered daily. The serum was analysed for Ca, Mg, and Pi (inorganic phosphate), Fe, FFA (free fatty acid) and beta-HB (hydroxybutyrate) and the plasma for the trace elements Cu, Zn, and Mn. After calving the milk yield (FCM) and the milk composition (fat, protein, lactose and urea) were analysed. Feed intake of group B, amounting to 6.2 +/- 1.3 kg DM/d was around 48% lower as compared to 12.0 +/- 1.4 kg DM/d for group A. The zeolite addition into the TMR showed a stabilizing effect on the average Ca concentration in the serum around calving. This effect led to a significantly lower Mg concentration on the day of calving and 1 day post partum. The Pi concentration was significantly lower already after the 1st week of zeolite supplementation and on the day of calving as compared to group A. There was no essential effect of zeolite A on the trace element concentration. The depression of feed intake for group B led to a significant increase of FFA one week after beginning zeolite supplementation and of beta-HB around calving. The feed intake post partum as well as the milk yield were not affected by zeolite supplementation. Because decreased feed intake of group B after zeolite supplementation and the occurred hypophosphatemia, it is not acceptable to use zeolite A in the proved dose for preventing milk fever.     

The effect of Saccharomyces cerevisiae1026 used alone or with vitamin-mineral premix on biochemical parameters of blood and milk in dairy cows

When evaluating the effects of yeast culture (Saccharomyces cerevisiae1026) supplied with or without a vitamin premix and mineral bioplexes on some intermediates and end-products involved in the synthesis of milk constituents in 30 early-lactation Black and White Lowland cows, no significant differences were found in the glucose level, mineral contents and enzyme activities of the blood serum. The effect of yeast culture on the availability of minerals for milk synthesis depended upon the dynamics of degradation of mineral bioplexes in the rumen and the cows' mineral status. The insignificant increase found in blood total protein content and the simultaneous small differences in blood urea nitrogen (BUN) and milk urea nitrogen (MUN) values in cows supplied with the yeast culture were probably associated with a high ammonia incorporation into microbial protein in the rumen, which increased protein supply for milk protein synthesis and decreased the nitrogen loss.     

Influence of abomasal infusion of high levels of lysine or methionine, or both, on ruminal fermentation, eating behavior, and performance of lactating dairy cows

Four multiparous late-lactation Holstein cows were fed a basal ration designed to be co-limiting in intestinally absorbable supplies of methionine and lysine. Cows were supplemented with no amino acids, lysine by abomasal infusion to 140% of the calculated intestinally absorbable requirement, methionine by abomasal infusion to 140% of requirement, or both amino acids in a 4 x 4 Latin square design with 28-d periods. Unsupplemented cows consumed 23.8 kg/d of dry matter and produced 36.9 kg/d of milk containing 3.70% fat, 3.22% protein, and 4.82% lactose. Cows ate less dry matter and produced less milk and milk lactose, and tended (P = .06 or .08) to produce less milk protein when abomasally infused with methionine alone or together with lysine. Infusion of lysine alone resulted in production values numerically between those of unsupplemented cows and those cows supplemented with methionine alone or together with lysine. Evaluation of the results with two metabolic models of dairy cows indicated that performance of unsupplemented cows may have been limited by delivery of metabolizable or digestible protein, or intestinally absorbable lysine, isoleucine, or histidine, depending on the metabolic model used to evaluate animal performance. Regardless, results are consistent with those using nonruminant species, which have shown that imbalanced profiles of intestinally absorbable amino acids are associated with reduced dry matter intake and animal performance. Results also show that negative effects on performance of lactating dairy cows can occur if methionine is supplied at levels substantially in excess of calculated intestinally absorbable requirements, either alone or together with lysine.     

放牧对乳成分和乳产品感官品质影响的研究进展

集约化养殖提高了牧场奶牛的生产效率,其生产过程中动物福利、环境保护以及产品质量等议题也逐渐引起消费者的关注。放牧养殖将户外放牧和牧草采食作为养殖模式的评判标准,其产品正逐渐受到欧美等发达国家消费者的青睐。饲料中的优质牧草是影响乳成分及其乳制品品质的主要因素之一,牧草中较高的纤维含量维持了瘤胃健康,较高的不饱和脂肪酸提高了乳脂中不饱和脂肪酸的比例,丰富的可降解蛋白提供了乳蛋白的合成原料,并且牧草中脂肪酸、氨基酸、碳水化合物和其他营养物质在奶牛体内的代谢影响了牛奶以及乳制品的感官品质。作者重点关注一些国家放牧养殖的实际状况和标准要求,及其与有机养殖的差异对比,并分析放牧养殖和全混合日粮喂养条件下饲料成分差异对奶牛瘤胃代谢的影响,以及由此造成的牛奶脂肪、蛋白成分和感官指标等方面的差异。     

Effect of parity number on the dry matter intake of dairy cows during the first week after calving

We investigated the effect of parity number on the dry matter intake (DMI) of cows during the first week after calving. Eighty‐three cows were evaluated from 14 days before to 7 days after calving. DMI and milk yield were measured for 7 days after calving, and the calving score was measured. Blood samples were collected throughout the experiment. The average DMI during the first week after calving was reduced in the first‐lactation heifers and high‐parity number cows. A quadratic relationship between the parity number and the DMI was observed. The first‐lactation heifers had lower prepartum serum total protein (TP) concentration and milk yield, higher prepartum serum nonesterified fatty acid (NEFA) concentration and calving score than the multiparous cows. The recovery rate of serum calcium (Ca) after calving was slow in the cows in the parity 6. The DMI was positively affected by the serum Ca concentration after calving, milk yield, and prepartum serum TP concentration and was negatively affected by the calving score and prepartum serum NEFA concentration. We conclude that the DMI immediately after calving tends to be lower in first‐lactation heifers and high‐parity number cows, but factors that reduce the DMI differ according to parity number.     

A first estimate of the amino acid requirement for milk production of the high-producing female mink (Mustela vison)

Thirty mink dams nursing litters of six kits were assigned to one of three dietary treatments [high protein (HP), medium protein (MP) and low protein (LP)], fed ad libitum for 4 week from parturition, to investigate the effects of protein supply on milk yield and milk composition in order to estimate the amino acid requirement of the lactating mink. Twelve dams were held in an intensive care unit and subjected to balance experiments and the kits were injected with deuterium oxide to determine water kinetics and milk yield. Eighteen dams were kept under normal farm conditions but with feed intake of dams and live weight gain of kits being determined and milk samples collected. The ME intake was higher (p < 0.05) in dams fed the LP and MP diets than in dams fed the HP diet, whereas the amino acid intake (g/day) was lowest (p < 0.05) in dams fed the LP diet. In the third and fourth weeks of lactation milk yield was higher (p < 0.05) in dams fed the LP and MP diets than in dams fed the HP diet. Chemical composition of milk was not affected (p > 0.05) by dietary treatment. However, protein content tended (p = 0.06) to be lower in dams fed the LP diet. Amino acid content (g/16 g N) of milk was higher (p < 0.05) in dams fed the LP and MP diets than in dams fed the HP diet. This resulted in the highest (p < 0.05) amino acid intake and highest (p < 0.001) live weights of kits nursed by dams fed the LP and MP diets, which may be explained by a combined effect of higher ME intake and reduced energetic costs for glucose production through less amino acids being used in gluconeogenesis. In conclusion, the improved performance of dams fed the LP diet suggested that their requirement of essential amino acids and non-specific N were covered, and the requirement of digestible amino acids of lactating mink (kg(0.75)) was, thereby, estimated by use of a factorial approach including the amino acid excretion in milk of LP dams.