Blood and tissue distribution of gamma glutamyl transferase in the cow.

To test the hepatic specificity of gamma-glutamyl transferase in the cow, the tissue distribution of this enzyme was studied in 10 healthy adult cows. It was located mainly in kidney, pancreas, and liver. The relative hepatic specificity of this enzyme indicated that measurement of its activity in serum could be a valuable test of hepatic damage in the cow. The blood activity measured within 54 plasmas and 54 serums of apparently healthy animals was almost the same, 17.7 +/- 5.7 U/liter for plasma and 18.6 +/- 6.2 U/liter for serum.     

Influence of a wide range of calcium intakes on tissue distribution of macroelements and microelements in dairy calves

Sixteen intact male Holstein calves averaging 86 kg and 63 d of age were assigned randomly to four treatment groups. The four treatment diets contained .17, .67, 1.31, and 2.35% Ca on an as-fed basis. The resulting Ca:P ratios with P held constant at about .34% were .47:1, 1.92:1, 3.83:1, and 7.20:1. Calves were fed diets at 3% of their body weights for 4 wk. Magnesium in the bone ash and serum was lowered by the 2.35% Ca treatment. Serum inorganic P was also reduced by the highest Ca diet during the last 2 wk of the experiment. Liver had the highest concentration of Zn in calves fed .67% Ca, and the muscle from calves fed 1.31% Ca diet had the lowest amount of Zn. Copper was reduced in pancreas for 1.31% Ca diet, but Ca was highest in the muscle and heart at the .67% Ca treatment. Weight gains and feed efficiencies were not affected by Ca. Fecal pH was different among treatments and increased as Ca intake increased. Young growing dairy calves can adapt to a wide range of Ca intakes and Ca:P ratios and maintain a moderate growth rate for 4 wk. It appears that excessive dietary Ca may affect concentrations of Zn, Fe, Cu, and Mn in some body tissues, but the magnitude of the effect is relatively small.     

Effects of sometribove on zinc metabolism and tissue mineral concentration in dairy calves.

The metabolism of Zn and tissue mineral concentrations were studied after a single oral 65Zn dose in 10 6-wk-old Holstein calves injected subcutaneously daily with 0 (control) or 10 mg of sometribove (recombinant methionyl bST) for 6 wk. Zinc-65 absorption was not significantly affected by bST; its concentration in the semitendinosus muscle was reduced by 32% in the bST calves, but concentrations in liver, pancreas, spleen, kidney, heart, small intestine, testicle, and rib were not different from controls. Manganese content was reduced by 27% in liver, 60% in kidney, 99% in spleen, 92% in testicles, and 33% in rib. Iron content of pancreas, spleen, and testicle and Zn content of rib were increased in the bST calves. The data indicate that Zn metabolism was not affected adversely by bST. Manganese content of several tissues was significantly reduced in the bST calves; however, no clinical signs of an Mn deficiency were evident.     

Blood hemoglobin, plasma iron, and tissue iron in dams in late gestation, at calving, and in veal calves at delivery and later.

The effect of 100 ppm of Fe in milk replacer on some hematological and tissue Fe variables was studied during the first 7 wk of the fattening period in two groups of eight calves with low or high initial blood hemoglobin concentrations. Hemoglobin concentration in calves with initially low hemoglobin increased. It decreased in those with initially high hemoglobin, but the difference remained over the experimental period. Higher mean liver Fe concentration, in some cases extremely high, and lower mean total Fe-binding capacity were found throughout the experiment in the group with the initial high hemoglobin. Of all variables, only low muscle Fe concentrations were correlated linearly with plasma Fe. In another experiment, the relationship of some hematological and tissue Fe variables during late gestation (about 10 d prepartum), at calving in dams, and at delivery in calves was investigated. The calves showed markedly higher liver Fe concentrations at delivery than their dams just before delivery, but these liver Fe concentrations were not correlated between dam and calf. The hematological and tissue Fe variables showed a weak correlation between dams and calves during late gestation or at delivery. However, dams as well as calves were Fe-sufficient.     

Blood studies and performance among calves reared by different methods

Three methods of feeding calves were compared as follows: 1) milk replacer only with restricted movement, 2) milk replacer only with freedom of movement, and 3) hay, grain, and water with freedom of movement. No significant differences were noted for variables of acid-base balance (sampled while resting). An Fe deficiency, microcytic, hypochromic anemia, developed in the calves receiving milk replacer only. Average daily gain, carcass grade, and sale price were superior for calves receiving only milk replacer with freedom of movement as compared with those with restricted movement. A fourth method (calves nursing cows), represented by calves having a different origin, was compared as a supplemental group. Absolute numbers for lymphocyte and neutrophils were significantly higher for calves nursing cows than for calves reared by the other methods.     

Intracellular distribution of zinc and zinc-65 in calves receiving high but nontoxic amounts of zinc.

The zinc homeostatic control breakdown in cattle fed a high but nontoxic amount of zinc was investigated. Liver copper was decreased by the 600 ppm added dietary zinc indicating altered copper metabolism. However, duodenal copper, liver and duodenal iron and manganese were not affected. Zinc-65 in blood was reduced 90% by the high dietary zinc 48 h following oral zinc-65 dosing. The 600 ppm supplemental zinc increased zinc by 500% in liver, 20 times in pancreas and kidney, and 100% in the duodenum. The increased liver and duodenal zinc was confined largely to the soluble cell fraction. This concentrating of excess tissue zinc in the soluble fraction may be an adaptive mechanism which detoxifies large quantities of zinc and prevents disruption of normal cellular activity.     

Short communication: effects of X-rays on growth and germinal tissue of calves

A study was carried out to measure the growth and germinal tissue responses of young bull calf whose testicles were exposed to different levels of high energy, pulsed beams (X rays). Treatments (absorbed doses) were 0, 1530, 1980, 3060, or 6300 rads. Body weights were measured monthly for 10 mo; testosterone concentrations were measured in mo 2 and 5. At the end of the study, scrotal circumferences were measured, and testes were removed and weighed. Sections of testes were taken, processed, and evaluated for effects on germinal epithelium. Treatments did not affect body weights or weight gains. Testosterone concentrations at mo 5 generally decreased with increased energy dose. Testicular weights were not different among treatments; generally, scrotal circumferences decreased and germinal tissue degeneration increased as the absorbed dose was increased.     

Treatment and control of neonatal diarrhea in calves.

Treatment and control of acute neonatal diarrhea in calves are outlined and discussed. The difficulty in making a definitive etiological diagnosis makes effective treatment and control also difficult and largely empirical. Physiological events in calves with diarrhea are known, and fluid therapy is directed toward treating dehydration and acidosis. Whether affected calves should receive antibacterial agents orally is an open question. Principles of control of diarrhea in calves are outlined and discussed.     

Fat content and fatty acid pattern in muscle and adipose tissue from differently reared calves

Two groups of Simmental calves were fed a milk replacer diet or were early weaned and slaughtered at the age of 4 months. Two muscles and two adipose tissue samples were removed, the lipids were extracted by chloroform-methanol and the fatty acid composition was analyzed by gas chromatography after transesterification with Na-methylate. Total lipid contents in both muscles were relatively small (<2%) Due to high phospholipid content, veal muscle lipids contain a high proportion of polyene fatty acids which accounted for more than 30%. Adipose tissue consists predominantly of oleic acid (from 34% to 37%) and palmitic acid (from 27% to 29%). In extractable perinephric fat, milk replacer diet caused significantly higher myristic acid (C(14)) values and, accordingly, lower oleic (C(18:1)) values.     

Short-term and long-term effects of early nutritional deprivation on adipose tissue growth and metabolism in calves

Two groups of 10 Friesian calves received, respectively, 819 and 1380 g of milk replacer daily between birth and 95 d of age. After weaning, both groups were pair-fed until slaughter at 533 d of age. Body composition, cellularity, and lipogenic activity of kidney and omental fat were determined at 95 and 533 d of age. Milk intake restriction produced a 40% reduction of growth rate and a 68% decrease in lipid deposition between birth and 95 d of age. This was accompanied by a reduced adipose cell hypertrophy without any effect on adipose cell number. Acetate incorporation in isolated cells, glucose 6-phosphate dehydrogenase, NADP-malate dehydrogenase, and lipoprotein lipase activities were lower in restricted animals. Glucose incorporation in isolated fat cells was very slight in both groups. Acetate incorporation and lipogenic enzyme activities were more than 10 times higher in 533-d-old animals that have larger adipocytes than in younger calves. Moreover, kidney fat presented a higher rate of de novo fatty acid synthesis than omental fat. The reverse order was observed for lipoprotein lipase activity. Early postnatal nutrition had no significant effect on lipid deposition between 95 and 533 d of age. There were no significant differences in body composition, adipose tissue cellularity, or metabolism at slaughter.     

Blood responses of calves fed milk substitutes containing hydrolyzed fish protein and lime-treated corn flour

Two experiments involving 3- to 5-d-old dairy calves were carried out. In Experiment 1, lime-treated corn flour (Nixtamal) supplied 50 to 100% of carbohydrates in a milk substitute based on sodium caseinate, lard, and cerelose. In Experiment 2, partially hydrolyzed fish protein concentrate replaced 50% of 67% of proteins in milk substitutes based on skim milk powder, lard, and 35% Nixtamal. Increasing the proportion of carbohydrates supplied by Nixtamal was associated with a linear decrease of postprandial serum glucose and insulin. Postprandial fluctuations in blood glucose were less in calves fed Nixtamal than in controls. Nixtamal probably was trapped within the casein clot in the abomasum, leading to delayed rate of passage of Nixtamal carbohydrates into the intestine. Replacing skim milk protein with hydrolyzed fish protein in diets containing Nixtamal had no effect on blood glucose or insulin but elevated free essential amino acids, which promoted glucagon secretion. More uniform concentrations of blood essential amino acids and glucose were related to lower blood urea at 54 d in calves fed diets based on hydrolyzed fish protein and Nixtamal, than that of control calves. It is suggested that more uniform postprandial blood glucose concentrations might reduce amino acid degradation for energy purposes and stimulate protein synthesis. Young dairy calves may adapt to milk substitutes based on Nixtamal and hydrolyzed fish protein despite changes in the concentration patterns of several blood components.     

Iodine absorption, excretion, recycling, and tissue distribution in the dairy cow.

Research on iodine metabolism was reviewed with special reference to cattle and milk secretion. Iodine metabolism in the fetus and thyroid activity as related to milk secretion and iodine feeding have also been considered. Between 70 and 90% of dietary iodine is absorbed directly from the bovine rumen, reticulum, and omasum. In the abomasum, rate of iodide secretion is approximately 18 times the rate of absorption. Circulating thyroxine is not secreted into the abomasum but enters the small intestine in the bile. Most of the iodide secreted into the abomasum is reabsorbed from the small and large intestines; absorption of thyroxine averages less than 10%. The thyroid usually contains an amount of iodine equal to the daily dietary intake; extrathyroidal tissues concentrate only .006 to .04% as much radioiodine per unit weight as the thyroid. At normal iodine intake (less than 10 mug/kg body weight daily), iodine losses average 30% of the daily intake in feces, 40% in urine, and 8% in milk. Milk iodine is influenced by amount and chemical form of dietary iodine, stage of lactation or milk yield, seasonal effects, goitrogens, and thyroid status. Cows secrete less iodine into milk than most other species and have an efficient iodine recycling system via the gastrointestinal tract which conserves iodine and can protect them against low dietary iodine.     

Blood parameters of young calves at abattoirs are related to distance transported and farm of origin

Nonreplacement dairy calves, or bobby calves, are fasted and transported to abattoirs from as young as 5 d of age in Australia. The aims of this cross-sectional observational study were (1) to assess the welfare status, as measured by blood parameters, of bobby calves in the commercial supply chain after transport and lairage, and (2) to assess whether distance and duration of transport are risk factors for poor bobby calf welfare, as measured by blood parameters. We hypothesized that bobby calves transported greater distances would be more likely to show evidence of compromised welfare, as measured by blood indicators of hydration, energy status, and muscle fatigue or damage. We also hypothesized that there would be a large amount of variability in indicators of energy status between calves from different farms. We analyzed blood samples collected at slaughter over a spring and an autumn calving period from 4,484 Australian bobby calves aged approximately 5 to 14 d old from 3 different states, after transport, fasting, and lairage. Packed cell volume (PCV), plasma glucose, and serum urea, total protein, β-hydroxybutyrate (BHB), and creatine kinase (CK) were measured. Radio frequency identification ear tag data were used to estimate the distance that the calves were transported and to identify the farm of origin. Data were analyzed using linear mixed models, except for BHB, which was analyzed using a Goodman-Kruskal gamma test due to left censoring of the data. Twelve percent of calves showed evidence of anemia (PCV less than 0.23 L/L), and 11% had urea concentrations consistent with dehydration (urea more than 7.7 mmol/L). Thirty-six percent of calves had CK activity above normal resting values, and 1% of calves had CK >2,000 U/L, indicating muscle fatigue or damage. Distance transported had significant effects on all blood variables except urea and BHB. With increasing distance transported, calves were more likely to show evidence of a negative energy balance (low plasma glucose) or dehydration (high PCV or total protein). The estimated effect of distance overall was small, but for calves transported more than 500 km, plasma glucose concentration declined more per kilometer. The calves' farm of origin accounted for a reasonable amount of the random variation between calves for plasma glucose (20%). Our results suggest that longer transport distances may increase the risk of poor calf welfare (dehydration, negative energy balance) after transport, and on-farm calf management (e.g., nutrition, timing of feeding before transport) may affect transported calves' energy status; improving this area could result in better energy availability during fasting.     

Effect of dehydration and acidemia on the potassium content of muscle tissue and erythrocytes in calves with neonatal diarrhea

Disturbances of extracellular potassium (K) homeostasis in calves with severe neonatal diarrhea have been studied extensively. Although total body depletion of this predominantly intracellular electrolyte is generally thought to occur in diarrheic calves, the mechanisms through which K depletion occurs are poorly understood. The aim of this study was to investigate how intracellular K homeostasis is affected by dehydration and acidemia, the 2 most important metabolic disturbances in calves with naturally occurring diarrhea. Twenty-seven calves with naturally occurring neonatal diarrhea, pronounced dehydration, and acidemia, and 2 groups of 10 healthy control calves were included in this study. Blood samples and muscle biopsies were obtained immediately before initiation of treatment (T₀) and after complete rehydration and correction of acidemia (T₁) from diarrheic calves. Blood samples were used to perform blood gas, blood biochemical, and hematological analyses and to determine K content in erythrocytes. Muscle biopsies were used to determine muscle tissue K content and tissue dry matter. Controls were used to determine values for erythrocyte and muscle tissue K content in healthy neonatal calves for comparison with diarrheic calves. As defined by the inclusion criteria, diarrheic calves showed pronounced acidemia and dehydration at T₀. Mean muscle tissue K content and tissue dry matter remained unchanged between sampling times and did not differ from values measured in healthy control calves. Erythrocyte K content increased from 73.63 ± 13.73 to 77.64 ± 15.97 mmol/L (±standard deviation) but was associated with a concomitant decline in erythrocyte volume. Values measured at both sampling times in diarrheic calves did not differ from erythrocyte K measured in healthy control calves. The plasma K concentration (median [interquartile range]) decreased from 5.44 [4.76–6.17] to 4.16 [3.99–4.31] mmol/L between T₀ and T₁. Although changes in plasma [K] were associated with the degree of dehydration, neither dehydration nor acidemia was associated with changes of K content in muscle tissue or erythrocytes. In conclusion, severe dehydration and acidemia in diarrheic calves were not associated with notable changes in K content of muscle tissue or erythrocytes. These results do not support the concept of pronounced K depletion occurring in calves with neonatal diarrhea. Erythrocytes are a poor surrogate tissue in which to measure changes of intracellular K content in diarrheic calves because of concomitant changes in erythrocyte volume that complicate the interpretation of results.     

Colostral immunoglobulin transfer in calves. IV. Effect of suckling

The greater absorption of colostral immunoglobulin in neonate calves suckling their dams over bottle-feeding pooled colostrum was studied to determine if age (hours postpartum) at initial feeding, amount of colostrum ingested, or mothering effect of being with the dam were responsible. Rate of absorption and maximum absorption were superior in calves that suckled, regardless of age or amount of colostrum ingested. Though the mothering effect is questionable, there is evidence that something labile is being transferred to the calf in the fresh colostrum, acting as a messenger to stimulate rapid absorptive activity in the intestinal epithelium.