Interrelationships in lactating Holsteins of rectal and skin temperatures, milk yield and composition, dry matter intake, body weight, and feed efficiency in summer in Alabama.

Thirty-two lactating, multiparous Holstein cows were utilized in a 91-d experiment in Auburn, Alabama, during summer to determine whether rectal and skin temperatures and respiration rates are repeatable and interrelated and whether whole cottonseed or calcium salts of long-chain fatty acids (Megalac, Church & Dwight Co., Inc., Princeton, NJ) affected milk production or its constituents. Treatments were (I) control, (II) I plus 10.4% whole cottonseed, (III) I plus 2.6% Megalac, and (IV) I plus 5.2% whole cottonseed plus 1.3% Megalac. Data included 358 to 2644 measurements analyzed as a split-plot design of experiment. Only milk protein percentage and protein-to-fat ratio were significantly affected by dietary treatment. Milk protein percentage was depressed by dietary fat additions, especially by the combination of whole cottonseed and Megalac. Within lactation repeatabilities for milk, fat, protein, and SCM yields ranged from 0.44 to 0.66; two percentages and protein to fat ratio, 0.21 to 0.32; feed efficiency, 0.18; dry matter intake (DMI) and body weight, 0.98 and 0.84; rectal and skin temperatures and respiration rate, 0.001 to 0.055. Partial and simple correlations were similar in sign and magnitude. Noteworthy were partial correlations between milk yield and DMI, 0.367; milk yield and rectal temperature, -0.135; milkyield and respiration rate, 0.102. Skin temperature was unrelated to other variables. Respiration rate was correlated with DMI, 0.270. Results should help researchers designing future experiments involving these responses to predict the number of measures needed to detect differences.

Supplemental shade for dairy calves reared in commercial calf hutches in a southern climate.

Two studies were conducted during consecutive years to determine the effects of providing supplemental shade to dairy calves reared in commercial hutches made of translucent plastic in a southern environment. Calves were assigned at birth to polyethylene calf hutches located in either an open control area or under supplemental shade (n = 9 to 12 per group per year). Shade reduced temperatures both inside the hutches and in the outer exercise areas during both years. However, shade increased humidity in the exercise area during yr 1. Shaded calves had lower rectal temperatures than control calves during yr 1, but differences were not significant during yr 2. Shade did not alter plasma cortisol concentrations. Shaded calves consumed less concentrate feed but had average daily gains that were similar to those of control calves, resulting in a tendency for greater feed efficiency for shaded calves. Counts for both total and fecal coliforms were greater in bedding collected from hutches under supplemental shade, but there was no difference in the incidence of health disorders. Providing supplemental shade to calves reared in plastic hutches in a warm southern environment altered the calf environment in a predictable manner but had little effect on overall growth and health.

Protein and methionine hydroxy analog for lactating cows.

A 2 X 2 factorial experiment (protein 12.5 and 15.5; methionine hydroxy analog 0 and .125% dry matter) included 144 cows for one complete lactation, distributed over seven locations. Rations were formulated to the desired protein, methionine analog, and constant amounts of fiber 17%, sulfur .225%, calcium .6%, phosphorus .4%, and salt .5%. Treatment effects were not apparent for dry matter intake, daily milk and fat-corrected milk production, conversion of energy, and body weight changes. Conversion of dietary crude protein into milk protein was 34.5% for the low and 25.8% for the high protein ration. Methionine analon (0% = 2.54; .125% = 1.90). Effect of methionine analog was most apparent at low protein as 0 analog cows produced 247 kg fat, required 2.9 services/contraception, and had 156 days open whereas cows on other treatments (.125% analog and/or high protein) produced 264 kg fat, required 1.8 to 2.2 services/conception, and had 124 to 134 days open. Methionine analog response is discussed in relation to tuminal and postruminal effects as well as the interrelation with protein and energy.

Mustard meal in dairy rations.

Consumption of 0% mustard meal and 15% soybean meal, 7.5% mustard meal and 7.5% soybean meal, or 15% mustard meal and 0% soybean meal rations did not differ in palatability studies with 10 group-fed lactating cows when the mustard meal was treated with 3% caustic soda. Order of preference was for 0, 7.5, and 15% mustard meal rations when mustard meal was untreated. Twelve lactating cows were in each of two lactation trials to compare the three rations of untreated mustard meal. Milk, milk fat, and solids-not-fat, and milk protein did not differ for either trial. Protein-bound iodine of plasma for all cows were within the normal range. Three cows were placed on each of the three rations and received a minimum of 9 kg per day for 6 mo preparturition to determine goitrogenic effects. All cows gave birth to normal, vigorous calves. Limited organoleptic evaluations of milk indicated that untreated mustard meal may impart a detrimental flavor to milk, but a taste panel could not differentiate between milk from cows on the three rations of treated mustard meal. Twenty-one male and 43 female Holstein claves received either 0, 10, or 20% mustard meal starter rations from birth to 3 mo of age. Growth, feed consumption, or plasma protein-bound iodine did not differ.

Effect of thyroid status and thiocyanate on absorption and excretion of iodine by cattle.

Effects of throidectomy or iodine-131, thyroprotein feeding, and thiocyanate dosing on radioiodine metabolism in the bovine were studied in 34 animals. Two thyroidectomized calves excreted 44% more radioiodine in urine and 38% less in feces than two thyroid-tact calves. Oral thiocyanate increased urinary radioiodine 32% in throidectomized and 46% in intact calves while reducing fecal radioiodine 48% in throidectomize and 11% in intact calves. Urninary radioiodine clearance of two heifers was increased 52% by thiocyanate, but urine flow was not affected. Percentages of radioiodine doses cycled through the abomasum daily and recovered from digestive tracts at slaughter, respectively, were: 12 thyroid-intact cows, 468 and 77; two intact cows fed 10 g sodium thiocyanate daily,64 and 41; 10 thyroid-damagedcows, 506 and 149; and four thyroid-damaged cows fed 8 g thyroprotein daily, 372 and 93. Thyroid damage had little effect on gastric radioiodine secretion but increased total digestive tract radioiodine because of greater volume of tract contents. Inhibition of gastric radioiodine secretion by thiocyanate reduced the digestive tract radioiodine pool. The digestive tract iodine pool may conserve iodine by reducing loss in urine.