Relationship between parity and mineral status in dairy cows during the periparturient period

Data from 65 cows were collected to clarify the relationship between parity and mineral status in Holstein cows during the periparturient period. Milk fever occurred in a second‐ and a fourth‐lactation cow at parturition. Bodyweight of cows decreased immediately after parturition, and the decreased weights of cows from 1 to 6 days after parturition ranged from 11 to 27 kg. Milk yield of multiparous cows was higher than that of primiparous cows, but Ca and P concentrations in colostrum were not affected by the parity. Plasma glucose of primiparous cows was higher than that of multiparous cows, and plasma nonesterified fatty acids of fourth‐and‐more‐lactation cows at parturition was highest. Plasma Ca concentration of cows at parturition decreased with advancing parity, and plasma inorganic P concentration of third‐and‐more‐lactation cows was lowest at parturition. Plasma parathyroid hormone of fourth‐and‐more‐lactation cows at parturition was highest, but plasma hydroxyproline and alkaline phosphatase was lowest. These results suggest that the large transfer of Ca and P to colostrum is a factor in the development of milk fever in third‐and‐more‐lactation cows.     

Postpartum supplemental fat, but not maternal body condition score at parturition, affects plasma and adipose tissue fatty acid profiles of suckling beef calves

Three-year-old Angus x Gelbvieh beef cows, which were nutritionally managed to achieve a BCS of 4 +/- 0.07 (479 +/- 36 kg of BW) or 6 +/- 0.07 (580 +/- 53 kg of BW) at parturition, were used in a 2-yr experiment (n = 36/yr) to determine the effects of maternal BCS at parturition and postpartum lipid supplementation on fatty acid profile of suckling calf plasma and adipose tissue. Beginning 3 d postpartum, cows within each BCS were assigned randomly to 1 of 3 treatments in which cows were all fed hay and either a low-fat (control) supplement or supplements with either high-linoleate cracked safflower seeds (linoleate) or high-oleate cracked safflower seeds (oleate) until d 61 of lactation. Diets were formulated to be isonitrogenous and isocaloric, and safflower seed supplements were provided to achieve 5% of DMI as fat. Total concentration of fatty acids in plasma did not differ (P = 0.48) due to maternal BCS at parturition. Percentage of 20:5n-3 in plasma tended (P = 0.06) to be greater for calves suckling cows with a BCS of 6 at parturition. No other differences (P = 0.12 to 0.99) were noted in calf plasma fatty acid profile due to maternal BCS at parturition. Likewise, no differences were detected for total fatty acid concentration (P = 0.88) in calf adipose tissue due to maternal BCS at parturition. Weight percentage of 14:1 (P = 0.001) was greatest in adipose tissue of calves suckling cows fed control and oleate; however, the percentages of 14:0, 15:0, 16:0, 16:1, 17:0, and 18:3n-3 were greater (P < 0.001) in adipose tissue from calves suckling cows fed control compared with calves suckling cows fed linoleate or oleate. Percentages of 18:0, 18:1trans-11, 18:2n-6, and cis-9, trans-11 CLA were greater (P < 0.001) in adipose tissue from calves suckling cows fed linoleate compared with calves suckling cows fed control and oleate. Calves suckling cows fed oleate had greater (P < 0.001) percentages of 18:1trans-9, 18:1trans-10, and 18:1cis-9 in adipose tissue than calves suckling cows fed control or linoleate. Calf plasma and adipose tissue fatty acid profiles were reflective of milk fatty acids. Because fatty acids play an important role in metabolic regulatory functions, changes in milk fatty acid profile should be considered when beef cows are fed lipid supplements.     

The effect of clover silage treated with acrylic acid on selected indicators of metabolism in cows around the time of parturition and the status of their calves]

A trial was conducted with 16 cows divided into control and test group (eight cows in either); since day 57.6 +/- 21.1 before parturition, test cows were given feed rations for 107 days which contained 16.0 kg clover-grass silage a day, treated with 3 l acrylic acid per t ensiled matter. Control group of cows was administered feed rations containing silage treated with 4 l formic acid per 1 t ensiled matter from day 55.5 +/- 21.9. In the blood (plasma) of test cows the alkaline phosphatase activity was increasing gradually, in the time after parturition a tendency of lower glucose (P 0.05 to 0.01), thyroxine and triiodothyronine concentrations was observed, and the phagocytal activity of leucocytes and its index decreased. The levels of ketone bodies and aspartate aminotransferase activity were found to be higher. In this period in urine the pH value and net acid-base output were lower, while the inorganic phosphorus concentration was higher. No difference were observed in colostrum density, liveweight of born calves and in the target metabolic parameters in the blood (plasma) of calves. In the 30-day period of investigation the cows of test group gave an average daily milk yield lower by 1.5 l (in comparison with control cows). The residues of acrylic acid (method sensitivity of 1.0 mg acrylic acid in 1 l sample) were not detected in their colostrum and milk.     

Effects of colostral antibody on susceptibility of calves to Cryptosporidium parvum infection

Effects of colostral antibody on susceptibility of calves to Cryptosporidium parvum infection were examined. Six calves were fed pooled colostrum that contained C parvum antibody, 6 times daily (at 4-hour intervals) for 7 days and then milk replacer for 7 days. Colostrum was obtained from healthy cows or cows inoculated parenterally with C parvum oocysts before parturition. Antibody content was determined in serum and colostrum whey, using an ELISA for anticryptosporidia immunoglobulin. Six calves were fed colostrum from healthy cows 1 time, and then milk replacer 6 times daily for 14 days. On day 1, all calves were challenge exposed with C parvum, PO, and were monitored daily for diarrhea and oocyst shedding. Bovine colostrum containing specific antibody to C parvum, at ELISA titers up to 10,240, was not effective in protecting calves against challenge exposure to C parvum.     

The effect of subclinical ketosis in dry cows on the composition of the colostrum and on health indicators in newborn calves

Subclinical ketosis of dry cows was studied as to its effect on the composition of colostrum and on the health condition and selected clinico-biochemical parameters in the new-born calves of these cows. The experimental group consisted of eight cows with ketonuria and their calves. The control group consisted of six cows without ketonuria and their new-born calves. Calves of both groups were reared in similar conditions. Colostrum samples were taken from the first milking and then from the milking 24 hours after parturition. The blood of the calves was sampled before the intake of colostrum and 24 hours after birth. The concentration of ketone bodies, particularly beta-hydroxybutyrate, was much higher in the colostrum of both groups of cows than in the blood (62.6 mg total ketone bodies per 1 litre of the first colostrum of the cows of the experimental group). The concentration of ketone bodies slightly increased after parturition. The cows with ketonuria secreted into colostrum a larger amount of oxidated ketone bodies. Colostrum quality was good in both groups. Decreased viability was not recorded during the clinical examination of the calves after birth. The level of total ketone bodies in the blood of pre-colostral calves in the experimental group was 10.4 mg per litre (a much lower concentration than in blood of their dams), and exhibited no appreciable change after taking in the colostrum. The blood of calves born to cows with ketonuria contained significantly higher amounts of oxidated ketone bodies. No correlation was demonstrated between the contents of ketone bodies in the blood of cows, in the blood of calves, and in the colostrum. The calves of the experimental group were found to have a significantly higher AST activity in plasma, as compared with the control group. Twenty-four hours after birth, the quantity of immunoglobulins in the blood serum was significantly lower in the calves of the experimental group. Thanks to good attendance and hygiene, the morbidity did not increase and no losses occurred.     

Iodine Content in Colostrum and Milk of Cows and Sows

The concentration of total iodine in colostrum and normal milk of cows and sows has been determined using a Technicon Autoanalyzer. In cows as well as in sows a lowering of the level of iodine in milk was observed during the first few days after parturition. At the first sampling within 8 hrs. after parturition the concentration of iodine in colostrum of cows from 2 herds was on average 3.4 and 2.4 μg/100 ml, respectively. Corresponding value for colostrum of the sows was 67 μg/100 ml. Based on informations about the composition of the food and daily food consumption it could be estimated that 0.5–1 and 20–45 % of the daily intake of iodine were secreted per 1 milk or colostrum of cows and sows, respectively. It can be concluded that the mammary gland of the sow has a considerably higher ability to concentrate iodine than that of the cow. Furthermore the concentration mechanism is more efficient immediately after parturition than at later stages of lactation.     

Determination of serologic and colostral response in late-gestation cows vaccinated with a Mycoplasma bovis bacterin

OBJECTIVE: To determine whether vaccinating cows during late gestation against Mycoplasma bovis will result in adequate concentrations of M bovis-specific IgG(1) in serum, colostrum, and milk. ANIMALS: 78 dairy cows. PROCEDURES: Serum samples were obtained 60 and 39 days prior to expected parturition in vaccinated and control cows from a single herd. Serum and colostrum samples were also obtained at parturition. Milk samples were obtained 7 to 14 days after parturition. Samples were analyzed for anti-M bovis IgG(1) concentrations. RESULTS: Prior to vaccination, control and vaccinated cows had similar anti-M bovis IgG(1) concentrations. After initial vaccination and subsequent booster and at parturition, there was a significant difference between the 2 groups, with vaccinated cows having higher IgG concentrations. Colostrum from vaccinated cows had higher anti-M bovis IgG(1) concentrations, compared with control cows; however, IgG(1) concentrations in milk did not differ between the 2 groups. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination of late-gestation cows resulted in increased concentrations of anti-M bovis IgG(1) in colostrum. However, ingestion of colostrum by calves may not guarantee protection against M bovis infection.     

Plasma vitamin A status in calves fed colostrum from cows that were fed vitamin A during late pregnancy

Calves are born vitamin A and β‐carotene deficient and the β‐carotene conversion to vitamin A is limited. Colostrum, contains relatively large amounts of vitamin A and β‐carotene and the retinol and β‐carotene status of calves can be normalized with colostrum consumption. We studied whether vitamin A supplementation of cows during late gestation (dry period) increases cow plasma retinol concentrations, the retinol content of first colostrum, and the plasma vitamin A status of calves during their first month of life. Both plasma and colostrum retinol concentrations were higher in vitamin A supplemented cows than in non‐supplemented cows. In calves that were for 5 days fed colostrum (milk) from vitamin A‐supplemented cows and then mature milk, plasma retinol concentrations were higher from 14 to 30 days after birth than in calves that were fed colostrum (milk) from cows that were not vitamin A supplemented. The study shows that vitamin A supplementation of cows during the dry period can improve the vitamin A status of their calves up to 1 month, if calves ingest their colostrum/milk for up to 5 days.     

基于蛋白质组学技术分析初乳和常乳摄入对初生犊牛肝脏蛋白表达的影响

【目的】试验旨在对犊牛肝脏蛋白进行蛋白质组学分析,筛选与初乳、常乳摄入相关的蛋白。【方法】以经产荷斯坦母牛分娩的9头公犊牛为研究对象,随机分为初乳组(CI)、常乳组(M)和对照组(CT),每组3头。初乳组和常乳组犊牛分别饲喂初乳和常乳,于出生后24 h屠宰;对照组未饲喂初乳或常乳,于出生后2 h屠宰。采用Label-free蛋白组学技术对3组犊牛肝脏的蛋白表达谱进行分析,以Q<0.05为阈值筛选各组间的差异表达蛋白,并进行GO功能和KEGG通路富集分析。【结果】在犊牛肝脏中共鉴定到3 901个蛋白,其中在初乳组、常乳组和对照组中分别鉴定到3 521、3 646和3 548个蛋白,有3 202个蛋白在3组中共表达。对差异表达蛋白进行分析显示,初乳组和常乳组犊牛肝脏中共筛选出287个差异表达蛋白,主要参与细胞代谢、应激反应、生长发育和氧化还原等生物过程,显著富集通路为内吞作用、氨基酸代谢和氧化磷酸化;初乳组和对照组犊牛肝脏中共筛选出154个差异表达蛋白,主要参与细胞代谢、单组织过程和肌酸合成等生物过程,显著富集通路为氨基酸代谢、黏着斑和内吞作用等。【结论】饲喂初乳的犊牛肝脏中差异表达...     

The hematocrit values and hemoglobin content of blood and the level of total protein, free fatty acids, glucose, lactate, Ca, Mg, Na, K, Pa, Fe, Fe-binding capacity, Cu and Zn in the blood plasma of newborn calves and their mothers immediately after birth

Blood samples were collected from 22 calves in three weight classes (A: 29.3 +/- 0.5 kg, B: 36.0 +/- 1.3 kg, C: 42.7 +/- 3.7 kg), 1-3 minutes after parturition and prior to uptake of foremilk as well as 24-26 hours after parturition. Other blood samples were collected from 45 calves, 5-60 minutes after parturition, and from their mothers, 3-5 or 5-60 minutes from calving. Haematocrit and haemoglobin in the blood of the calves, immediately after parturition, were higher the values recorded from adult cattle. Major differences were found to exist between individual calves regarding total protein of blood plasma. Protein levels in 14 calves were below 50 g/l, within 24-26 hours from parturition. Free fatty acids in blood plasma of calves were lower than those in cattle, 1-3 minutes from parturition, and were higher, 5-60 minutes from parturition. Glucose levels in Group C were higher than those in A and B, 1-3 minutes postpartum. Lactate in Group C was higher than that in B. An account is also given of blood plasma levels of Ca, Pa, Mg, Na, K, Cu, and Zn.     

Biologic quality of colostrum and calves from dairy cows injected with zinc during pregnancy]

The effects of an administration of the Zindep inj. preparation (Biotika) were evaluated in pregnant dairy cows as exerted on specific weight, total protein (TP) content, total immunoglobulin (IgC) and albumin (ALB) contents in colostrum. These parameters were also followed: calf's health, live weight, leucocyte (Lc) counts, T-lymphocyte (T-Ly) counts, contents of TPs, IgCs and ALBs in the blood serum of calves. Zinc concentrations were determined in colostrum, milk and calf blood serum. Our observations included 16 dairy cows in the seventh month of pregnancy in the second lactation and their calves in the winter feeding season. Eight experimental dairy cows were treated with the Zindep preparation in form of an injection to the neck muscles at a dose of 3 mg Zn/kg live weight in the mid-seventh month of pregnancy. Blood samples were taken from v. jugularis from all calves before their first drinking, on days 5, 15 and 30 of age. Colostrum, and/or milk samples were obtained by drawing of the colostrum or milk from the udder quarters within 60 minutes after parturition, on days 5 and 15 of lactation. Zn levels at birth were 16.48 +/- 2.67 mumol/l in experimental calves and 13.84 +/- 3.19 mumol/l in control calves. Zincaemia decreased slightly in both groups on days 5 and 15 of age, but it was insignificantly higher in calves coming from Zindep-treated dairy cows. Zn levels in the blood serum on the 30th day of age were 18.45 +/- 2.44 mumol/l in experimental animals and 15.73 +/- 3.11 mumol/l in control animals. Zn content in the colostrum of experimental cows was 2.40 +/- 0.42 mg/l and in the control it was 1088 +/- 0.52 mg/l (P < 0.05). On day 5 of lactation, Zn amounts in the milk of experimental dairy cows decreased to 0.95 +/- 0.12 mg/l and to 0.76 +/- 0.10 mg/l in the control (P < 0.01). Zn levels in the milk of experimental cows on day 15 of lactation were 0.95 +/- 0.13 mg/l and in the milk of control group they were 0.82 +/- 0.14 mg/l. Colostrum specific weight from zinc-treated cows was 1,067.86 +/- 0.75 g/cm3 and 1,056.8 +/- 13.53 g/cm3 in the control. TP and IgC concentrations were 137.81 +/- 38.11 g/l and 110.13 +/- 29.91 U ZST, respectively, in the colostrum of experimental group, and 105.98 +/- 32.02 g/l and 85.53 +/- 25.42 U ZST, resp., in control animals.(ABSTRACT TRUNCATED AT 400 WORDS)     

The effect of energy-rich feed supplements for cows on the health of their calves]

Experiments were carried out with 24 pregnant cows and their calves. The cows were divided in 2 equal groups. One of these received a supplement of animal fat additional to the feed from 4 weeks a. p. to 6 weeks p. p. Apart from clinical examinations following laboratory investigations in the blood were performed: hematological parameters, cholesterol, lipids, free fatty acids, ketone bodies, protein, glucose, bilirubin, transaminases, alkaline phosphatase, Ca, Mg, P, K, Na, Cl. The addition of fat to the feed of cows influenced the energy metabolism of the cows, the body weight of the newborn ones and some hematological parameters (incl. protein) of the calves positively.     

Effects of low and high calcium intake prepartum on calcium mobilization rate around parturition in dairy cows

Forty-one dairy cows were fed a low (LCa-13 g/d) and a high (HCa-83.5 g/d) calcium ration in the 8 weeks prior to parturition and the effect on the Ca mobilization rate around parturition was studied. Plasma Ca values were stable in the LCa group around parturition. In the older cows of the HCa group a very slight decrease in the mean plasma Ca was observed: 2.58 mmol/l at 12-36 h ante partum decreased to 2.38 mmol/l at parturition. Hypocalcaemia, which commonly occurs around parturition, did not occur in 40 of the cows. A subclinical hypocalcaemia (1.8 mmol/l) occurred in one cow (parity 10) from the HCa group. To assess the efficiency of Ca mobilization, a severe hypocalcaemia (1.0 mmol/l) with clinical signs was induced by means of Na2EDTA infusion (0.90 mmol/min), starting at 10 h post-partum. The older cows in the LCa group required more Na2EDTA than those in the HCa group. Higher urinary hydroxyproline excretion in the week before parturition in the LCa than in the HCa group suggested a higher bone turnover. Plasma PTH levels around parturition were not significantly different between the groups. The amount of colostrum milked out in the first 10 h post-partum did not influence Ca homeostasis around parturition. The results contradict those of many other experiments in which hypocalcaemia was observed in cows ingesting high levels of Ca. It is concluded that the restricted feed intake prepartum possibly had a favourable effect on Ca homeostasis.     

Vaccination of pregnant cows with K99 antigen of enterotoxigenic Escherichia coli and protection by colostrum in newborn calves

The immune response to the K99 was tested in 45 pregnant cows, subcutaneously vaccinated, for protecting the newborn calves. Serological tests were performed in the blood sera of all animals and in the milk and colostrum sera; hemogram, inhibition of the adhesion to the brush border and histological tests were performed. The calves from vaccinated cows survived the experimental infection after the suction of colostrum in spite of the fact that the calves from control dams died with diarrhea.     

安格斯母牛初乳产量与质量测定及其新生犊牛被动免疫效果评价

【目的】 新生犊牛被动免疫转移失败（failure of passive transfer,FPT）会导致犊牛发病率和死亡率显著增高,影响后期生长发育。本试验针对国外引进的安格斯母牛初乳产量和质量进行测定,并对其新生犊牛被动免疫效果进行评估,以期为新生犊牛初乳管理措施制定提供科学依据。【方法】 随机选择健康安格斯初产母牛（24月龄）和经产母牛（36~48月龄）各15头,待母牛产犊后立即进行人工挤奶测定初乳产量、营养成分及免疫球蛋白浓度。选取初产和经产新生犊牛各15头,测定其初生重,分别采集犊牛出生后未食初乳（0 h）和食初乳后（24~36 h）血样,测定其血清总蛋白含量及各生理生化指标。【结果】 初产母牛平均初乳产量极显著低于经产母牛,但其初乳中乳蛋白、非脂乳固体、乳糖、灰分含量,以及密度和电导率均极显著高于经产母牛（P<0.01）。初产母牛和经产母牛初乳中免疫球蛋白浓度分别为28.72%和26.24%,合格率分别为93.33%和91.67%,差异均不显著（P>0.05）;初产和经产新生犊牛被动免疫失败率分别为33.3%和25.0%;初产新生犊牛平均初生重极显著低于经产新生犊牛（P<0.01）;被动免疫成功犊牛平均初生重和球蛋白含量均极显著高于被动免疫失败犊牛（P<0.01）。【结论】 新疆安格斯犊牛FPT的主要原因可能是母牛初乳产量低导致新生犊牛初乳摄入不足,初生重较低的犊牛FPT的风险性较高。本研究为制定切实可行的新生安格斯犊牛初乳补饲计划提供了科学基础。     

Concentrations of macro- and micro-elements in the milk of pasture-fed thoroughbred mares

OBJECTIVE: To determine the changes in Ca, P, Mg, Na, K, S, Cu, Fe and Zn concentrations of milk during the lactation in pasture-fed Thoroughbred mares and then calculate the dietary mineral requirements of the sucking foal and the lactating mare. PROCEDURE: Milk was sampled on days 1, 3, 7, 14, 21, 28 and at various times between 55 to 65, 85 to 95 and 135 to 150 days after parturition from 21 pasture-fed mares. The concentrations of macro- and micro-elements in the milk were determined by inductively coupled plasma emission spectrometry. RESULTS: Concentrations (mg/L) of these elements were highest in colostrum (Mg 302, Na 561, K 955, S 1035, Cu 0.76, Fe 0.79 and Zn 5.5) except for Ca (1245) and P (895), which where highest on day 7. The mean milk mineral element concentrations (mg/L) over days 55 to 150 were Ca 843, P 543, Mg 47, Na 120, K 590, S 219, Cu 0.19, Fe 0.34 and Zn 2.1. The mean plasma element concentrations (mg/L) over the same period were Ca 120, P 77.1, Mg 17.0, Na 3110, K 168, S 983, Cu 1.1, Fe 1.5 and Zn 0.49. Concentration gradients between plasma and milk were observed and, in the case of Ca, P, Mg, K and Zn, their concentrations in milk were greater than those in plasma, while a reverse situation was observed for Na, S, Cu and Fe. CONCLUSION: With the exception of Ca and P, the highest concentrations of mineral elements were observed in the colostrum. The nursing foal should have access to good pasture or creep feed, because the intakes of Ca, P and Cu from milk may be less than optimum to meet the daily mineral element requirements.     

Conjugated linoleic acid content in adipose tissue of calves suckling beef cows on pasture and supplemented with raw or extruded soybeans

The concentration of CLA in adipose tissue can be increased in ruminants by feeding pasture and extruded soybeans. The objective of this study was to evaluate maternal supplementation of raw (RS) or extruded (ES) soybeans on the concentrations of CLA in milk fat of cows and s.c. adipose tissue of suckling calves. Thirty-two spring-calving cows (BW 624 +/- 76 kg; BCS 3.5 +/- 0.4; mean +/- SD) and calves (BW 127 +/- 15 kg) were separated into 2 groups. Cows were distributed to have 8 calves of each sex in both groups. When animals were turned out to pasture, dams received 2 kg/d of either RS or ES. Dietary treatments had no effect on average milk intake (P = 0.22) and pasture forage intake (P = 0.13) for calves over the course of the grazing season. As a result, no effect of treatments was observed on ADG (P = 0.26). At weaning, milk fat content of CLA reached 15.4 and 24.2 mg/g of total fatty acids for cows fed RS and ES, respectively (P = 0.02). The CLA concentrations in adipose tissue were 16.9 and 25.0 mg/g of total fatty acids for calves suckling dams fed RS and ES, respectively (P < 0.001). Overall, results demonstrated supplementing grazing cows with ES increased CLA content in milk and adipose tissue of suckling calves.     

Effects of postpartum dietary fat and body condition score at parturition on plasma, adipose tissue, and milk fatty acid composition of lactating beef cows

Two experiments were conducted with lactating Angus x Gelbvieh beef cows to determine the effects of postpartum lipid supplementation, BCS at parturition, and day of lactation on fatty acid profiles in plasma, adipose tissue, and milk. In Exp. 1, 36 pri-miparous cows (488 +/- 10 kg of initial BW; 5.5 +/- 0.02 initial BCS) were given ad libitum access to hay and assigned randomly to a low-fat (control) supplement or supplements with cracked, high-linoleate safflower seeds (linoleate) or cracked, high-oleate safflower seeds (oleate) from d 3 to 90 of lactation. Diets were formulated to be isonitrogenous and isocaloric; safflower seed diets provided 5% of DMI as fat. Plasma and milk samples were collected on d 30, 60, and 90 of lactation. Adipose tissue biopsies were collected near the tail-head region of cows on d 45 and 90 of lactation. In Exp. 2, 3-yr-old cows achieving a BCS of 4 +/- 0.07 (479 +/- 36 kg of BW) or 6 +/- 0.07 (580 +/- 53 kg of BW) at parturition were used in a 2-yr experiment (n = 36/yr). Beginning 3 d postpartum through d 61 of lactation, cows were fed diets similar to those of Exp. 1. Adipose tissue and milk samples were collected on d 30 and 60, and plasma was collected on d 31 and 61 of lactation. Responses to postpartum dietary treatment were comparable in both experiments. Cows fed linoleate and oleate had greater (P < 0.001) total fatty acid concentrations in plasma than cows fed control. Except for 15:1, milk fatty acids with <18 carbons were greatest (P < or = 0.01) for cows fed control, whereas milk from cows fed linoleate had the greatest (P < or = 0.02) 18:1trans-11, 18:2n-6, and cis-9, trans-11 CLA. Milk from cows fed oleate had the greatest (P < 0.001) 18:1cis-9. In Exp. 1, total fatty acid concentrations in adipose tissue samples decreased at d 90 compared with d 45 of lactation, but the fatty acid profile of cow adipose tissue was not affected (P = 0.14 to 0.80) by dietary treatment. In Exp. 2, the percentage of cis-9, trans-11 CLA in adipose tissue of cows with a BCS of 6 decreased (P = 0.001) from d 30 to 60 of lactation. Plasma and milk fatty acid composition reflected alterations in postpartum diet. Less medium-chain fatty acids and more 18-carbon fatty acids in milk were indicative of reduced de novo fatty acid synthesis in the mammary gland of beef cows fed lipid supplements; however, the metabolic demands of lactation prevented the deposition of exogenously derived fatty acids in adipose tissue through d 90 of lactation.     

Effect of colostrum intake on diarrhoea incidence in new-born calves

In a survey which lasted one year and included data of 73 dairy cows with their calves, colostrum immunoglobulin G (IgG) of 22 primiparous cows and serum IgG of their calves were lower than the corresponding IgG levels of 51 multiparous cows and their calves. Serum IgG concentration was not correlated with diarrhoea incidence. Although there were no seasonal differences in the IgG concentration of colostrum and calf serum, neonatal diarrhoea incidence was higher in calves which were born in winter than in calves which were born in summer (P < 0.01). Thus the high diarrhoea incidence in winter was not a consequence of an insufficient IgG transfer to the calves. The 60 calves of the second study were fed colostrum on the first day of life. From the second to the tenth day 28 experimental calves received milk and 0.5 l of surplus colostrum of the first and second milking twice a day, whereas 32 control calves received milk only twice a day. Two of the 28 experimental and 11 of the 32 control calves suffered from diarrhoea during the first ten days of life (P < 0.05). These results show that the ingestion of surplus colostrum in addition to milk after the first day of life protects the new-born calf against infectious diarrhoea.     

饲粮钙磷水平对伊犁马初乳成分、乳脂脂肪酸组成、产后血液钙磷及激素的影响

旨在研究妊娠后期饲喂不同钙磷水平饲粮对产后伊犁马初乳成分、乳脂脂肪酸组成、血液钙磷及钙磷代谢激素、繁殖及生长代谢激素等生理生化指标的影响，为明确伊犁马在妊娠后期对钙磷的适宜需要量提供参考。本试验选取健康、无亲缘关系、12~13周岁、体重为（380±32）kg、胎次为4~5胎、处于第10妊娠月左右的伊犁马25匹，随机分为5组，每组5个重复。各组饲粮钙饲喂水平分别为36.00、39.00、42.00、45.00和48.00 g·d^-1，磷饲喂水平分别为26.30、28.30、30.30、32.30和34.30 g·d^-1。试验预试期10 d，正试期从第11天至母马分娩后第2天结束。母马分娩后12 h内采集初乳用于测定乳成分和乳脂脂肪酸含量，空腹血液用于测定Ca、P、甲状旁腺素（PTH）、降钙素（CT）、骨钙素（OC）、胎盘催乳素（PL）、垂体催乳素（PRL）、雌酮（E₁）、雌二醇（E₂）、血清孕酮（PROG）、甲状腺素（T₄）、三碘甲状腺原氨酸（T₃）、生长激素（GH）、胰岛素样生长因子-Ⅰ（IGF-1）等激素浓度。结果表明：1）饲粮钙磷水平对初乳中钙、磷、乳脂率、乳糖率均无显著影响，组间乳蛋白率、总固形物、体细胞数、乳脂中饱和脂肪酸（SFA）和不饱和脂肪酸（UFA）比例存在显著差异（P<0.05）。随着饲粮钙、磷水平的增加，乳磷浓度、乳蛋白率和UFA比例呈显著线性增加（P<0.05），总固形物呈显著二次增加（P<0.05），而乳糖率、SFA及肉豆蔻酸比例呈显著线性降低（P<0.05）。2）饲粮钙磷水平显著影响血液中OC和PROG浓度（P<0.05），随着饲粮钙磷水平的增加，血液中离子钙、CT和OC浓度呈显著的线性降低（P<0.05），而PTH和PROG水平呈显著的线性升高（P<0.05）。饲粮钙、磷水平对PL、PRL、E₁、E₂等生殖激素以及T₃、T₄、GH和IGF-1等生长代谢激素浓度均无显著影响。由此可见，在本试验条件下，饲粮钙磷通过提高初乳中乳蛋白率和总固形物来改变乳脂中饱和脂肪酸含量和不饱和脂肪酸比例影响初乳成分；通过降低血液中OC浓度影响钙磷代谢；通过提高血液中PROG浓度影响繁殖状况。