Limiting total mixed ration availability alters eating and rumination patterns of lactating dairy cows.

The objective of this study was to investigate the effect of restricting total mixed ration (TMR) eating time with or without supplemental long hay offered on diurnal total intake, rumination, and rumen pH patterns in mid-lactation dairy cows. Eight multiparous Holstein cows were used in a replicated 4 × 4 Latin square design study with 21-d periods. The basal diet was the same for all 4 treatments with or without additional long grass hay (the same hay used in the TMR). For cows on limited-time TMR, diets were taken away at 1500 h (5 h before evening milking and feeding), and dry matter intake (DMI), ruminating, and rumen pH were monitored and summarized every 10 m for 7 d in each period. With restricted feeding, cows changed DMI patterns by consuming a large meal after feed was reinstated, resulting in lower DMI. Ruminating patterns closely mirrored intake patterns, as could be expected. Rumen pH was not different between groups but resulted in different diurnal patterns due to differences in eating and rumination patterns between the groups. Limiting feed availability can be used to change eating and rumination patterns, resulting in different rumen pH patterns.

Fecal particle dry matter and fiber distribution of heifers fed ad libitum and restricted with low and high forage quality.

Wet sieving of manure can be used as a means of evaluating the nutrient utilization of diets by dairy cows. A commercially available system for this analysis (Nasco Digestion Analyzer, Nasco, Fort Atkinson, WI; NDA) employs principles of wet sieving for on-farm assessment. The objective of this study was to evaluate effects of diet manipulations and sampling techniques on fecal particle dry matter (DM), neutral detergent fiber (NDF), and starch distribution on NDA sieves. Eight Holstein heifers (means ± SD; age 18.4 ± 0.6 mo and BW 457.2 ± 27.3 kg), were randomly assigned to a split-plot 4 × 3 incomplete Latin square experimental design with 18-d periods (15 d of adaptation and 3 d of sampling). Treatment rations differed in forage quality (high ADF <35%, low ADF >35%) and fiber content (high NDF >45%, low NDF <40%) and were offered to heifers for ad libitum and restricted intakes. Diets were fed to allow 900 to 1,000 g/d of body weight gain and fed once daily. Fecal grab samples were collected 0, 6, 12, and 18 h after feeding all 3 d of the sampling period, and the remaining feces was collected in the manner of total fecal collection to represent a daily composite sample. After wet sieving of each sample using a NDA kit, the retained material on sieves was dried and analyzed for DM, NDF, and starch content. Sampling day and feeding regimen did not affect distributions of nutrients. Distributions of total fecal particle DM were greater for high forage quality and high fiber content diets (14.66 to 20.37% of sample DM). The NDF content in retained material decreased with decreasing sieve size (from 89.81 to 86.86%) and was not affected by forage quality and fiber content, whereas NDF retained on NDA (% DM) followed the same pattern as the retained particle DM weight. Starch content in retained material was below 0.5% in the majority of diets. Average retained fecal particle DM and NDF content varied depending on the time after feeding, resulting in the large differences between grab fecal samples and a daily total composite sample. However, average values of retained particle DM and NDF weight for all sampling time points were similar to ones from total daily composite sample.

Short communication: Verifying Holstein heifer heart girth to body weight prediction equations.

The estimation of Holstein heifer body weight (BW) from heart girth measurements is needed, as many farms do not have animal scales to make the management decisions that require BW. The correlation between heart girth and BW is known to vary with differing animal conformation. The previous equation to correlate the 2 measures for Holstein dairy heifers was done 25 yr ago. Data were derived from 6 US experiment stations that are part of Regional Research Project NC-2042: Management Systems to Improve the Economic and Environmental Sustainability of Dairy Enterprises. After deriving a new equation from a data set of observations and using a second validation data set, it was determined that the equation developed in 1992 was still valid and further equation development was not needed at this time.

A prospective study of calf factors affecting first-lactation and lifetime milk production and age of cows when removed from the herd.

This prospective study was designed to investigate possible carryover effects of calf management practices and how events occurring during the first 16 wk of life affect first-lactation and lifetime milk production as well as age when animals are removed from production. This is the final of 3 stages in a longitudinal study that encompassed 10 yr of data collection. First, management and nutritional data were collected in the first 16 wk of life. The second part of this study evaluated conditions of animals at the time of first calving as affected by calf management, nutrition, and health. Both of these studies have been previously reported. This third portion covers the same calf effects on lactation performance and age at culling. Observations for the current study were collected from on-farm and Dairy Herd Improvement records. The multiple imputation technique was used in this analysis to avoid bias due to missing data. This study concluded that delivery score, weaning dry matter intake, days of illness before 4 mo, days treated before 4 mo, and body weight at first calving all had significant effects on first-lactation production of Holsteins. Delivery score and grain intake at a young age affected lifetime production. Age at culling was only affected by early grain intake in this study.

A prospective study of calf factors affecting age, body size, and body condition score at first calving of holstein dairy heifers.

Data were collected prospectively on parameters related to first calving on 18 farms located in Northeastern Pennsylvania. This project was designed to study possible residual effects of calf management practices and events occurring during the first 16 wk of life on age, BW, skeletal growth, and body condition score at first calving. Multiple imputation method for handling missing data was incorporated in these analyses. This method has the advantage over ad hoc single imputations because the appropriate error structure is maintained. Much similarity was found between the multiple imputation method and a traditional mixed model analysis, except that some estimates from the multiple imputation method seemed more logical in their effects on the parameter measured. Factors related to increased age at first calving were increased difficulty of delivery, antibiotic treatment of sick calves, increased amount of milk or milk replacer fed before weaning, reduced quality of forage fed to weaned calves, maximum humidity, mean daily temperature, and maximum ammonia levels in calf housing areas. Body weight at calving tended to increase with parity of the dam, increased amount of grain fed to calves, increased ammonia levels, and increased mean temperature of the calf housing area. Body condition score at calving tended to be positively influenced by delivery score at first calving, dam parity, and milk or milk replacer dry matter intake. Withers height at calving was positively affected by treatment of animals with antibiotics and increased mean temperature in the calf area. This study demonstrated that nutrition, housing, and management factors that affect health and growth of calves have long-term effects on the animal at least through first calving.

Effects of mannan oligosaccharide or antibiotics in neonatal diets on health and growth of dairy calves.

Seventy-two Holstein calves were used to study the effect of feeding antibiotics or mannan oligosaccharides (MOS) in milk replacer. Calves were fed a 20% protein, 20% fat milk replacer containing antibiotics (400 g/ton neomycin + 200 g/ton oxytetracycline), MOS (4 g of Bio-Mos/d), or no additive (control) for 5 wk. Milk replacer was reconstituted to 12.5% dry matter and fed at 12% of birth weight during wk 1 and 14% of birth weight in wk 2 to 5. Fecal scores were monitored 3 times per week; body weight, heart girth, withers height, hip height, and hip width were measured at birth and weekly to 6 wk of age. Addition of MOS or antibiotics increased the probability of normal scores for fecal fluidity, scours severity, and fecal consistency as compared to control calves during the course of the study. Consumption of calf starter increased at a faster rate in calves fed MOS, and these calves consumed more calf starter after weaning (wk 6), than those fed antibiotic. No treatment differences in growth measures, total blood protein, or blood urea nitrogen were detected during the trial. Addition of MOS or antibiotics to milk replacer improved fecal scores in calves. Feed intake was improved in MOS-fed calves compared to antibiotic-fed calves, but this difference did not result in growth differences during the experimental period. The results suggest that antibiotics in milk replacers can be replaced with compounds such as mannan oligosaccharides to obtain similar calf performance.

Influence of manganese deficiency on the characteristics of proteoglycans of avian epiphyseal growth plate cartilage.

The need for manganese for normal skeletal development appears to be related to its role in proteoglycan biosynthesis. The purpose of this research was to characterize the proteoglycans synthesized under conditions of manganese deficiency. The proteoglycans were extracted from epiphyseal growth plate cartilage and the monomers separated by cesium chloride density gradient centrifugation followed by column chromatography. The proteoglycan monomers from normal cartilage contained primarily (92%) chondroitin sulfate side chains with keratan sulfate being a minor (8%) component. Manganese deficiency reduced the total amount of cartilage proteoglycans. Of the monomers present in deficient cartilage, the majority (75%) were similar to those found in normal cartilage. Cartilage from deficient chicks also contained a second monomer fraction (25%) characterized by a reduced carbohydrate content. Thus, in addition to a reduction in total proteoglycan content, manganese deficiency results in qualitative changes in the proteoglycans present in epiphyseal growth plate cartilage.

Broiler chicks fed low calcium diets. 1. Influence of zeolite on growth rate and parameters of bone metabolism.

An experiment with a factorial arrangement of treatments was conducted using five levels of dietary calcium and two levels of zeolite A. When dietary calcium was deficient or marginal, zeolite A improved calcium utilization, as evidenced by improved growth rate and a reduction in rachitic lesions. There was little benefit from adding zeolite A to diets adequate in calcium. The effect of zeolite A on the incidence of tibial dyschondroplasia was inconsistent.

Effect of the sex-linked dwarfing gene (dw) upon skeletal development of young broiler chicks.

The influence of the sex-linked dwarfing gene (dw) on growth and skeletal development in young male broiler chicks was investigated. Chickens that were homozygous (dw/dw) for the dwarfing gene had significantly lower BW and tibiotarsus lengths when compared with the heterozygous (Dw/dw) or normal (Dw/Dw) genotypes. All genotypes exhibited similar incidences of tibial dyschondroplasia. In contrast to several other types of dwarfism, there was no effect of the dw gene on the width of the epiphyseal growth plate or the proteoglycan content of this tissue.

Effect of aluminum on performance and mineral metabolism in young chicks and laying hens.

This study was performed to determine the long-term effects of dietary aluminum on egg production and reproductive parameters in the mature laying hen and on growth rate and feed efficiency in young chicks. The diets used in these studies were adequate in phosphorus and other essential nutrients. Aluminum added to constitute 0.30% of the diet severely depressed growth and reduced feed efficiency, bone ash and plasma phosphorus in male Ross x Leghorn chicks. At the same time, 0.15% added aluminum mildly depressed growth, feed efficiency and bone ash but had no effect on plasma phosphorus levels. The reduction in bone ash was relatively mild, and no clinical signs of rickets were observed. In laying hens, diets containing 0.15% added aluminum did not affect egg production, but 0.30% added aluminum reduced production significantly. Long-term exposure to aluminum increased percent shell in both groups receiving aluminum, whereas egg weight remained similar to that in controls. There were no changes in hatchability or bone ash associated with dietary aluminum. Although dietary aluminum influenced bone aluminum content, egg aluminum content was not affected. These studies indicate that dietary aluminum interferes with systems in addition to phosphorus metabolism.