Holstein Heifer Calves Research Articles

Performance and Health of Dairy Calves Using Different Types of Commercial Housing

Three housing types for neonatal dairy calves were compared on a commercial 1500-cow dairy in central California. Three types of housing were: 2.0 × 1.0 × 1.0m wooden hutch; 2.0 × 1.0 × 1.3m thermolded opaque polymer hutch with an outdoor pen 1.4 × 1.8; and 2.0 × 1A × 1.3m molded opaque polyethylene hutch with an outdoor pen 1.7 × 1.5m. Effects of type of housing on grain intake, growth, stress indices, and health from birth through 6 wk of age were studied from August through October. Results from 29 Holstein heifer calves showed no differences (P>0.05) in grain intake and average daily gain regardless of housing type. Red blood cell count, white blood cell count, hemoglobin concentration, and hematocrit showed no (P>0.05) housing effects and were within normal ranges. The stress parameters of cortisol and neutrophil to lymphocyte ratio showed temporal effects (P<0.01) but not a housing effect.

Age-dependent changes in peripheral blood lymphocyte subpopulations in cattle: A longitudinal study

Immunofluorescence and flow cytometric analyses were used to study the age-dependent changes in the peripheral blood lymphocyte (PBL) subpopulations in cattle. Four healthy Holstein heifer calves (A, B, C and D), 1–2 months of age, were used in this study. Sequential peripheral blood samples were collected once a month for up to 2–2.5 years, and once at approximately 4 years of age. For the first 6 months of age, the calves had similar proportions of CD2 +, CD4 +, CD8 + T lymphocytes, CD20 + B lymphocytes and MHC class II + lymphocytes. From 2 months of age up to 2–2.5 years of age, all animals had similar proportions of CD5 + cells; but during the same period, animals A and B had significantly lower proportions of WC1 +γδ T cells than animals C and D. After 7 months of age, however, the proportions of CD2 +, CD4 + and CD8 + T cells in PBL of animals A and B significantly decreased, whereas the proportions of both CD20 + B lymphocytes and MHC class II + lymphocytes significantly increased. In contrast, the proportions of the various PBL subpopulations in animals C and D remained virtually unchanged after 7 months of age. For the first 6 months of age, all the calves showed similar absolute counts of PBL. Thereafter, the absolute counts of PBL in animals A and B significantly increased, but remained virtually unchanged in animals C and D. Throughout the study, from 1–2 months up to 2–2.5 years of age the absolute counts of CD2 +, CD4 +, CD8 + and WC1 +γδ T cells in PBL of the four animals were not significantly different from each other. Up to 6 months of age, the CD4 +/ CD8 + ratio in all calves was 2.38 ± 0.46, but significantly decreased thereafter to 1.81 ± 0.34. However, there were no significant differences in the CD4 + CD8 + ratios among individual animals. The increase in the absolute counts of PBL in animals A and B, after 7 months of age, was due to an increase in the absolute counts of CD5 + cells, CD20 + B lymphocytes and MHC class II + lymphocytes. Thus, changes in the percent, but not the absolute counts of T lymphocytes, were due to high percent and absolute counts of B lymphocytes, expressing the CD5 and MHC class II antigens.

Alterations in blood lymphocyte subpopulations and hematologic values in neonatal calves after administration of a combination of multiple-antigen vaccines

Objective To evaluate alterations in lymphocyte subpopulations, CBC results, and clinical signs in neonatal calves inoculated with 3 commercially available proprietary multiple-antigen vaccines containing known quantities of endotoxin. Design Prospective, randomized controlled field trial. Animals 36 healthy Holstein heifer calves between 3 and 31 days old. Procedure Vaccines were administered to 18 calves according to label instructions, except for the recommended age of administration. The 18 other calves served as unvaccinated controls. Two weeks after entry into the study, calves were given secondary doses of the same vaccines. Calves in both groups were examined and blood samples were collected for determination of lymphocyte subpopulations and hematological parameters once daily for 5 days beginning on the day that both the primary and the secondary vaccinations were given. Lymphocyte subpopulations, including BoCD2*, BoCD4+, BoCD8+, B cells, and γ/δ T cells, were determined by use of flow cytometry, using monoclonal antibodies as markers. Results Vaccinated calves did not develop clinical signs of illness. There were no significant differences in absolute numbers of lymphocyte subpopulations between vaccinated and unvaccinated calves. Vaccinated calves had significantly higher rectal temperatures, total WBC counts, and absolute neutrophil counts than did control calves. These differences persisted for 3 to 4 days after vaccination. Clinical Implications Findings confirm empirical observations that vaccination with multiple products at the same time may induce evidence of an inflammatory response in most calves. Additional research is indicated to further evaluate the safety of using multiple vaccines simultaneously. (J Am Vet Med Assoc 1996;209:638-642)

Effect of Plane of Nutrition Before and After 200 Kilograms of Body Weight on Mammary Development of Prepubertal Holstein Heifers

Twenty Holstein heifer calves at 138 d of age and 118kg of BW were assigned randomly to one of four treatments in a factorial design. Heifers were fed for low (0.7 kg/d) or high (>1.0 kg/d) gain during two periods. Period 1 was from start to 200kg of BW, and period 2 was from 200kg of BW to slaughter, which occurred in the middle of the luteal phase following the third estrus.Calves on the high plane of nutrition during period 2 were heavier at the end of trial and gained more BW between puberty and the end of trial. Those calves also had heavier mammary glands, which had more fat and dry fat-free tissue.Heifers that had been raised on the low plane of nutrition throughout the trial had greater concentrations of DNA and RNA but did not have greater protein in the dry fat-free tissue. Low plane of nutrition during either period increased DNA and RNA concentration in the dry fat-free tissue. Total mass of DNA and RNA did not differ among treatments. Protein mass was increased by the high plane of nutrition during period 2.This study indicated that dietary manipulation affects mammary dry fat-free tissue, protein, and adipose mass in the period up to and including puberty.

Management practices and risk factors for morbidity and mortality in Minnesota dairy heifer calves

This prospective study involved 845 Holstein heifer calves born during 1991 on 30 dairy farms in southeast Minnesota. The objectives of the part of the study reported here were to examine relationships between management practices and incidence of morbidity and mortality at both herd and individual-calf levels. A survey administered by the investigators identified the herd management practices. Check-off forms completed by cooperating producers captured the individual-calf risk factors. Data collected included events surrounding each calf's birth as well as treatments and disease diagnoses for each heifer calf. Outcomes of interest were any occurrence of enteritis, pneumonia, or death between birth and 16 weeks of age. Time, place and date of birth, ease of birth, colostrum administration and any other treatments at birth, housing and any other treatments were the risk factors of interest. The overall morbidity rate for the study was 0.2 calves treated per 100 calf-days at risk (range 0-0.8, standard deviation 0.2), while the rates for scours and pneumonia were 0.15 cases per 100 calf-days at risk (0-0.7, ± 0.2) and 0.10 (0-0.7, ± 0.2) cases per 100 calf-days at risk, respectively. The mortality rate for the study period was 0.08 deaths per 100 calf-days at risk (0-0.3, ± 0.08); 64 heifers (7.5%) died during the study. Mean average daily weight gains for heifers from birth to 16 weeks of age was 0.82 kg day −1 for all farms (0.45–1.1, ± 0.2). In general, stated herd management practices were practiced at the individual-calf level. Several herd management practices altered the outcomes of interest. For example, the feeding of a coccidiostat to preweaned calves increased the herd risk of pneumonia (relative risk, 3.38; 95% CI 1.34–8.50). The feeding of a vitamin A-D-E supplement to preweaned calves exerted a protective effect against scours (0.35, 0.13–0.93). Managing group pens for weaned calves in an ‘all-in, all-out’ fashion rather than in a continuous flow system contributed to a farm having an average daily rate of gain that was above the median (3.06, 1.34–6.97). The Cox proportional hazards model was used to describe relationships between risk factors and the outcomes of interest. Calves that required assisted delivery were at an increased risk of developing enteritis sooner than those that were born without assistance. No other risk factors had a significant effect.

Cortisol Increases in Plasma of Holstein Heifer Calves, from Handling and Method of Electrical Dehorning

Changes in cortisol in plasma were used to assess stress when calves were restrained and then dehorned. Thirteen Holstein heifer calves between 3 and 4 wk of age were used over 4 d; each calf served as its own control. On d 1, 2, and 4, blood was sampled initially while calves were in a pen, 5min after being placed in a restraint chute, and then at 5, 15, 30, and 45min and 1, 2, 3, 4, 8, and 12h after simulated or actual dehorning. On d 1, dehorning was simulated. On d 2 and 4, one horn bud of each calf was cauterized, respectively; sequence of horns (right, left) and dehorning instruments (conventional electrical, Buddex™) were alternated for all calves. Day or previous dehorning procedures had no effect on initial concentrations of cortisol in plasma. However, after calves were placed in a chute, cortisol in plasma increased with each entrance. Cortisol in plasma peaked at 5min posthandling (d 1, 11.3ng/ml) or 15min postdehorning (electrical, 21.9ng/ml; Buddex™, 20.7ng/ml). These data suggest that both dehorning procedures resulted in similar rates of synthesis and secretion of cortisol.

Effects of shipping, handling, adrenocorticotropic hormone, and epinephrine on α-tocopherol content of bovine blood

Summary In 2 studies, plasma, erythrocyte, and neutrophil α-tocopherol concentrations were monitored in beef cattle after shipping, handling, and sample collection. On the basis of α-tocopherol results, an additional 2 studies were designed to measure the effects of administration of adrenocorticotropic hormone (acth) and epinephrine on the α-tocopherol concentration in the aforementioned blood constituents and on creatine kinase (ck) activity in Holstein calves. In the first of these studies, 15 beef cattle that had recently arrived at the feedlot consumed feed supplemented daily with 1,000 IU of dl-α-tocopheryl acetate. Values for initial blood samples indicated that ck activity was high. Although plasma α-tocopherol concentration indicated that vitamin supplementation was adequate, rbc and neutrophil α-tocopherol values were generally nondetectable. After 4 weeks of supplementation, plasma α-tocopherol concentration increased (P &lt; 0.05), and neutrophil and rbc α-tocopherol values became measurable in most of the cattle. In the second study, 6 beef heifers had decreased (P &lt; 0.05) plasma, rbc, and neutrophil α-tocopherol values after multiple periods of handling and blood sample collection. In the third and fourth studies, 10 tamed Holstein heifer calves, 5 of which were administered acth and epinephrine to simulate stress effects on blood α-tocopherol concentrations and ck activity. In study 3, the vitamin E-adequate heifers had increased blood ck (P &lt; 0.001) activity and cortisol (P &lt; 0.01) concentration, and decreased (P &lt; 0.05) neutrophil α-tocopherol concentration after hormone injections. In study 4, when vitamin E-deficient calves received the aforementioned hormones, ck activity increased (P &lt; 0.05) and rbc α-tocopherol concentration decreased (P &lt; 0.05), whereas plasma and neutrophil values did not change. These results indicate that shipping and handling, or the stress paradigm of acth and epinephrine injections, may reduce the α-tocopherol content of plasma, rbc, and neutrophils while increasing plasma ck activity, which indicates membrane destruction.

A synthetic opioid peptide increases plasma growth hormone and prolactin in Holstein calves.

The effect of the synthetic opioid agonist D-Ala2,N-Me-Phe4,Met(O)5-ol enkephalin (DAMME) on plasma growth hormone (GH) and prolactin (PRL) concentrations in Holstein heifer calves was investigated in this study. The possible site of action of DAMME was determined by pretreating calves with an opioid antagonist that crosses the blood-brain barrier poorly if at all (N-methyl levallorphan-methane sulphonate [MLM]) or one that crosses readily (naloxone [NAL]). All calves were assigned to one of three treatment groups: 1) pretreatment with saline, 2) pretreatment with NAL, or 3) pretreatment with MLM. All groups were injected with DAMME 30 min after pretreatments. Plasma PRL increased after injection of DAMME in calves pretreated with saline. Prolactin concentrations were not different before and after injection of DAMME in calves pretreated with either NAL or MLM. Plasma GH increased after injection of DAMME in saline- and MLM-pretreated calves but was unchanged in NAL-pretreated calves. These data show that peripherally administered DAMME increases plasma GH and PRL in Holstein heifer calves and suggest that DAMME mediates GH release through receptors located somewhere inside the blood-brain barrier, but it can induce PRL secretion at a site located outside the barrier.

Effect of probiotic supplementation on growth rate, rumen metabolism, and nutrient digestibility in Holstein Heifer Calves

Effect of probiotic supplementation on growth rate, rumen metabolism, and nutrient digestibility in Holstein Heifer Calves

Performance and Ruminal Function Development of Young Calves Fed Diets with Aspergillus oryzae Fermentation Extract1,2

Neonatal Holstein heifer (n=72) and bull (n=40) calves were used to study the effects of Aspergillus oryzae fermentation extract (Amaferm) on their performance and on rumen development. The starter diets were formulated to achieve Amaferm consumption of 0, .5, 1, or 3g per calf daily. Calves were fed milk daily and allowed to consume starter and a mixture of alfalfa and bromegrass hay ad libitum. Weaning was when calves consumed 550g of starter on 2 consecutive d. Weight gain and feed consumption were recorded weekly. Forty of the heifer calves, 10 from each treatment, were selected randomly to study the effects of Amaferm on ruminal fermentative development. Ruminal fluid samples were collected for pH, ruminal fermentation products, and for bacterial enumerations.Overall, Amaferm-supplemented calves were weaned 1 wk earlier than unsupplemented calves. They had higher total VFA, propionate, and acetate concentrations in the rumen than unsupplemented calves. Total anaerobic, hemicellulolytic, and pectinolytic bacterial counts were higher; cellulolytic bacterial counts tended to be higher for the Amaferm-supplemented calves than for controls. In general, Amaferm-supplemented calves had greater ruminal microbial activity than those not fed Amaferm.

Exogenous opioids increase plasma prolactin in Holstein calves primarily via a dopaminergic mechanism

A study was conducted to determine whether exogenous opioids increase prolactin (PRL) secretion in Holstein heifer calves via a dopaminergic mechanism. Twenty-four Holstein heifer calves ranging in age from 5 to 7 mo were assigned to one of four treatment groups (six/treatment): 1) injection of saline (SAL); 2) injection of a synthetic enkephalin (D-Ala2, N-Me-Phe4, Met(O)5-ol enkephalin; DAMME); 3) injection of DAMME after pretreatment with the long-acting dopamine agonist 2-bromo-alpha-ergocryptine; or 4) injection of thyrotropin-releasing hormone (TRH) after pretreatment with 2-bromo-alpha-ergocryptine. Calves were equipped with indwelling jugular cannulas on d 1, and baseline plasma PRL concentrations were established. Animals receiving 2-bromo-alpha-ergocryptine were injected s.c. 3 h after the last baseline sample was drawn on d 1. On d 2, calves assigned to receive SAL, DAMME, or TRH were injected 2 h after the start of sampling, and sampling was continued for an additional 4.5 h. Basal plasma PRL was lower (P less than .01) on d 2 in calves injected with 2-bromo-alpha-ergocryptine than baseline levels on d 1. Plasma PRL was higher (P less than .01) in calves not pretreated with 2-bromo-alpha-ergocryptine after DAMME injection on d 2 but was not different after DAMME injection in calves pretreated with 2-bromo-alpha-ergocryptine. In contrast, plasma PRL increased (P less than .01) after TRH injection on d 2 in calves pretreated with 2-bromo-alpha-ergocryptine.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanical effects of sodium fluoride on bovine cortical bone

Seventeen 5 to 6-month-old Holstein heifer calves were divided into three groups and fed either a control ration alone or a control ration with sufficient sodium fluoride added to furnish an additional 30 or 50 p.p.m. fluoride based on total dry matter intake. After 6 years of the feedings, mean (SEM) fluoride concentrations in the metacarpals were found to be 594.6 (66.2), 2663.8 (319.2), and 4500.0 (417.8) p.p.m. Bone mineral density and mechanical evaluations were also conducted on the harvested metacarpals after the 6-year period. Using dual energy X-ray absorptiometry, mean (SEM) bone mineral densities of 3.030 (0.26), 2.801 (0.34), and 2.456 (0.19) g cm −2 for the control group, the group receiving 30 p.p.m. fluoride, and the group receiving 50 p.p.m. respectively were found. For the mechanical testing, specimens were cut and tested in compression parallel to the long axis of the metacarpals. Mean (SEM) ultimate stress of 204.53 (3.63), 208.83 (5.25), and 205.93 (5.12) MPa and mean (SEM) Young's elastic moduli of 20.82 (1.52), 22.68 (2.38), and 21.55 (1.60) GPa for the control, the 30 p.p.m., and the 50 p.p.m. fluoride groups respectively were determined. No significant differences were found between control and treatment groups for either mechanical properties or bone mineral density.

Changes in Blood Glucose, Nonesterified Fatty Acids, and Ketones in Response to Weaning and Feed Intake in Young Calves

Effects of weaning age on blood glucose, ketones, and nonesterifid fatty acids were examined using 16 Holstein heifer calves. Animals entered the study at 6±3.5 d of age and were fed 1.8kg of milk twice daily to 28 (early weaning) or 56 d (late weaning) and a commercial pelleted calf starter from 0 (early) or 28 d (late). Blood was sampled once weekly for 14wk and analyzed for β-hydroxybutyrate and acetoacetate. Plasma was analyzed for glucose and nonesterifid fatty acids. Blood β-hydroxybutyrate increased with increasing grain intake and was greater during wk 0 to 4 and 5 to 8 in calves weaned early than in those weaned late. Blood acetoacetate followed trends similar to β-hydroxybutyrate and averaged 23.8 and 16.1 μM in calves weaned early and late, respectively. Plasma glucose and nonesterifid fatty acids declined with age and were lower during 5 to 8wk in calves weaned early. Data suggest that ketone concentrations resulted from alimentary ketogenesis, which increased rapidly after weaning.

Changes in Plasma Volatile Fatty Acids in Response to Weaning and Feed Intake in Young Calves

Effects of weaning age on plasma VFA were examined using 16 Holstein heifer calves. Animals entered the study at 6±3.5 d of age and were fed 1.8kg milk twice daily to 28 (early weaning) or 56 d (late weaning) and a commercial pelleted calf starter from 0 (early) or 28 (late) d. Blood was sampled once weekly for 14 wk Total blood concentrations of VFA, acetate, propionate, and butyrate were higher in calves weaned early. Difference between treatments was greatest during wk 5 to 8, after early calves had been weaned. Total VFA and acetate were both highly correlated with grain intake (r = .77), whereas propionate (r = .47) and butyrate (r = .56) were less highly correlated. Data indicate that blood VFA responded rapidly to dry feed intake, and adaptation to high grain diets was complete by 1 to 2wk postweaning.

Effects of Handling, Administration of a Local Anesthetic, and Electrical Dehorning on Plasma Cortisol in Holstein Calves

Effects of handling, administration of a local anesthetic, and electrical dehorning on plasma cortisol were measured in Holstein heifer calves. Jugular blood was sampled from 24 calves (age, 7 to 16 wk) within 1 to 2min after entering their pen (baseline, 0800h). All calves were then haltered, placed in a restraint chute, an unheated electrical dehorner applied to each horn stump, and a second jugular blood sample obtained 30min later (handling). Calves were then divided into control and test groups (12 calves). For the next 2 consecutive d the sequence of sampling blood and handling were the same except that 1) for control calves a heated dehorner was used on d 2 (dehorning), and 2) for test calves the cornual nerve of each horn stump was injected with 5ml lidocaine prior to applying an unheated dehorner on d 2 (administration of anesthetic) and a heated dehorner on d 3 (combination of anesthetic and dehorning). Handling, injection of an anesthetic, and dehorning were stressful and increased plasma cortisol of calves 5.4, 16.8, and 28.3ng/ml above baseline, respectively. Dehorning and the combination of injecting lidocaine and dehorning resulted in similar increases in plasma cortisol. Different responses in plasma cortisol in individual calves exposed to similar stimuli suggest that synthesis and release of cortisol can be modified.

Evaluation of Content and Source of Phosphorus Fed to Dairy Calves

Twenty-four Holstein bull calves, 12 Holstein heifer calves, and 6 Jersey bull calves were assigned to a 2 × 3 factorial experiment at 8 to 9 wk of age. Three concentrations (.26, .34, and .41%) and two sources (feed grades monoammonium phosphate and dicalcium phosphate) of dietary P were fed during a 10-wk trial. The biological availability of monoammonium phosphate was equal to dicalcium phosphate as a supplemental P source. Increasing dietary P from .26 to .34% increased feed intake, body weight gain, plasma inorganic P, plasma Mg, bending moment of the tibia and ninth rib, percentage ash, and ash content (P and Mg) of the 7th and 10th ribs and lowered plasma Ca. Only plasma inorganic P increased from .34 to .41%. Treatment means for .26, .34, and .41% P, respectively, were feed intake (kg.d−1) 2.98, 3.48, and 3.34; daily body weight gain (kg.d−1) .83, .94, and .92; wk 9 and 10 plasma inorganic P (mg-100ml−1) 6.08, 8.38, and 9.05; bending moment (kg.cm) of the 9th rib 31.6, 47.6, and 40.7 and tibia 1314.84, 1783.94, and 1751.00. These results indicate a requirement for calves greater than the .26% P currently recommended.

Effects of Passive Immunity on Growth and Survival in the Dairy Heifer1,2

Effects of 24 to 48h serum Ig concentration on growth and survival of 1000 Holstein heifer calves were evaluated. Average serum Ig for all calves was 25.71 (SD = 19.06) mg/ml with a range of .05 to 108.27. Serum Ig concentrations were below 12 mg/ml in 28% of the heifers. Both season and age of dam contributed significantly to the variation in 24 to 48h concentrations of serum Ig. Concentration of serum Ig at 24 to 48h was a significant source of variation affecting average daily gain through the first 180 d of life. Seasonal factors also were significant in influencing rate of gain from birth to 180 d. Age of dam was a significant source of variation in calf weight gains but only for the first 35 d. Mortality was 6.78% for heifers with less than 12 mg/ml serum Ig at 24 to 48h as compared with 3.33% mortality for calves with greater than 12 mg/ml concentration.

Descriptive epidemiology of calfhood morbidity and mortality in New York holstein herds

A prospective cohort study was done of 1171 Holstein heifer calves born from July 1983 to 30 April 1985 and kept to be raised as replacements in 26 commercial dairy herds in the vicinity of Cornell University. The objectives were to examine the interrelationships of management with morbidity and mortality at both the individual and herd level, and the long-term effects of morbidity on survical. The study population, data collection and processing methods, and the descriptive epidemiology (e.g. age and temporal distributions) of calfhood morbidity, mortality and treatments are described. The clinical signs (as diagnosed by farmers on standardized check-off forms) studied were: scours/diarrhea within 14 days of birth and from 15 to 90 days of age; dull, listless, droopy ears, or of feed within 90 days of birth; cough, runny nose or eyes, or trouble breathing within 90 days or birth; death prior to 90 days of age. The crude incidence rates of scours within 14 days of birth, scours from 15 to 90 days of age, dullness, respiratory illness and death were 9.9, 5.2, 7.7, 7.4 and 3.5 per 100, respectively, for the period of study. The only seasonal effect on incidence was for scours within 14 days of birth (which was higher in winter compared to summer across both years of the study). The incidence rates of scours from 15 to 90 days of age, dullness and respiratory illness were higher in the first year of the study compared to the second year; there was no effect of season on these outcomes. The mortality rate within 90 days of birth was not related either to year of study or season. The median ages at occurence of scours within 14 days of birth, scours from 15 to 90 days of age, dullness, respiratory illness, and death were 6, 30, 16, 25 and 28 days, respectively. Risks of clinical signs were highest in the first week of life, while risk of death was highest in the third week. Calves with only scours within 14 days of birth or only scours from 15 to 90 days of age were treated primarily with oral electrolytes, oral antibiotics, and restriction of milk consumption. Calves with only dullness or only respiratory illness were treated primarily with intramuscular antibiotics. The median herd incidence rates of scours within 14 days og birth, scours from 15 to 90 days of age, dullness, respiratory illness and death were 5, 0, 0, 0 and 0 per 100, respectively, during the periof of the study.

Feeding and Management of Dairy Heifers for Optimal Lifetime Productivity

A total of 433 Holstein heifer calves were fed two different energy amounts from 6 wk of age to breeding weight to determine the effect of early nutrition and age at first calving on lifetime performance. A control group of 182 heifers was fed according to the Beltsville growth standard. A second group of 251 heifers was accelerated in growth by providing more energy during early development. Both groups of heifers were bred at a minimum weight of 340kg. Average ages at first calving for control and accelerated heifers were 24.6 mo and 22.2 mo with corresponding 305-d first lactation unadjusted milk production values of 6985 and 6729kg and unadjusted milk fat yields of 222 and 216kg. Average 305-d milk production values through subsequent lactations for control and accelerated animals, were lactation 2, 7790, 7842kg; lactation 3, 8200, 8330kg; lactation 4, 9481, 9134kg; lactation 5, 9865, 9588kg; lactation 6, 9515, 10,108; lactation 7, 9661, 10,112. Average total milk yields over five lactations were 42,321 and 41,623kg. Percentages of cows remaining in the herd after five lactations were 19 and 18 for control and accelerated animals. Reproductive problems, mastitis, and deaths accounted for 70% of cows leaving the herd and did not differ between treatment groups.

Increased Weight Gain and Effects on Growth Parameters of Holstein Heifer Calves from 3 to 12 Months of Age

Two trials involving 280 Holstein heifer calves were to determine effects of increasing nutrient intake on growth (weight, height, and heart girth), dry matter intake, and water intake. In trial 1, 80 calves were fed from 60 to 172 d of age. More calf grower fed increased daily gain from .87 to .92kg. Gain was further increased to .97kg with higher energy content and to .99kg with higher energy and higher protein content of calf growers. Alfalfa hay intake decreased as calf grower intake increased. Wither height and heart girth increased proportionally to body weight. Water intake was variable but proportional to dry matter intake. In trial 2, 114 heifers were fed alfalfa hay with either control or higher protein and higher energy heifer (accelerated program) growers from 187 to 369 d of age. Grass hay was fed to 86 heifers from 230 to 369 d of age with the same grower rations. Daily gain increased from .83 to .93kg with the accelerated program. Hay intake decreased with higher grower intake on the accelerated program. When fed ad libitum on both programs, grass hay intake was about 5% lower than alfalfa hay. Heart girth at 369 d of age was increased on the accelerated program but there was no effect on wither height. Growth of Holstein heifers can be accelerated up to 1kg daily gain from 3 to 12 mo of age without excessive fattening.