Recipient Organization
UNIVERSITY OF PUERTO RICO AT MAYAGUEZ
P. O. BOX 9000
MAYAGUEZ,PR 00681
Performing Department
Animal Science
Non Technical Summary
Research efforts to characterize the slick haired phenotype (SLICK) in the Bos taurus dairy breeds of Puerto Rico have shown greater thermoregulatory and productive capacities in these animals when compare to wild type haired (WT) similar cattle. However, these efforts have been almost exclusively limited to adult cows, resulting in a lack of knowledge in the early stages of life in these animals. To our knowledge, only preliminary data exist suggesting that SLICK heifers present different growth curves than WT ones, which probably results in differences in terms of when maturity is reached and mature size. Thus the proposed project aims to characterize the growth (body weight and dimensions) of SLICK and WT haired Puerto Rican Holstein calves / heifers between birth and 34 months of age. Also, the eating activity (through automatic sensors) and disease incidence will be characterize and their relationship with the respective growth patterns will be assessed as efficiency indices. Therefore, the study aims to achieve a better understanding of the growth and feed efficiencies of Puerto Rican dairy cattle.
Animal Health Component
25%
Research Effort Categories
Basic
75%
Applied
25%
Developmental
(N/A)
Goals / Objectives
1. Characterize the growth curves in SLICK and WT Puerto Rican Holstein calves / heifers.2. Evaluate the feeding and activity behaviors in these animals under the environmental conditions of PR.3. Document and evaluate the incidence of health problems and its association with growth for both hair coat types.4. Study the relationship between eating activity and growth in both hair type groups.
Project Methods
Evaluated animals will be obtained from the Agricultural Experiment Station (AES) dairy herd at Lajas and from a private dairy farm in Camuy, PR.Animals A total of 20 female Holstein calves (10 SLICK and 10 WT) in each location (Lajas and Camuy) will be used. Calves will be enrolled in the study at birth and classified by hair coat visually as early as possible, until the study groups are completed. In difficult cases, a retrospective visual classification will be made. Calves will be maintained under the regular management practices of the farms.Data collection During the milk feeding period, once a week beginning at birth, calves body weight (BW) will be recorded and their body dimensions will be measured (withers height, hip height, thoracic perimeter, barrel, shoulder to pin bone distance, BW / withers height, BW / hip height, BW / thoracic perimeter, BW / barrel, and BW / shoulder to pin bone distance) immediately after the morning feeding. After weaning, BW and dimensions values will be recorded once a month until 34 months of age (close to the average age at first parturition in the Lajas Herd). Each sampling day, disease incidence will be assessed on a scale from 0 - 3 (0 = heathy; 3 = severely ill) by the University of Wisconsin- Madison, School of Veterinary Medicine Calf Health Scoring Card (https://www.vetmed.wisc.edu/dms/fapm/fapmtools/8calf/calf_health_scoring_chart.pdf).Additionally, a nylon halter will be equipped with three position data loggers (HOBO Pendant G tri-axial accelerometer; Onset Computer Corporation, Pocasset, MA) to record eating activity (e.g. starter, hay and grass eating, drinking water or ruminating). Data loggers will be attached to the nose band, the lateral-medial side band (close to the jaw), and the bottom band of the nose. Each calf will carry a fourth position data logger at the external side of its right hind leg by means of a velcro strap to record physical activity (e.g. standing up, lying down, walking). Two preliminary trials using ten calves and ten heifers (half SLICK and half WT) will be performed to fine tune the halters and characterize animal movements and eating patterns. As previously described by others, these data loggers will record changes in acceleration and tilt in the x, y and z axis as the animal moves and eats. During the preliminary trials, the values recorded by the data loggers will be compared with visually recorded movement and eating observations in order to characterize the acceleration and tilt data that correspond to each behavior. Additionally, the values published by others, who have already done such characterization, will be used for validation. Once the heifers are allocated in the grazing paddocks they will also receive a neck nylon collar with an attached light sensor (HOBO Pendant MX; Onset Computer Corporation, Pocasset, MA) so the daily time spend grazing directly under the sun or resting under the shade can be recorded. A preliminary trial will be also carried out for the validation of the light sensors. To allow for adaptation, each calf / heifer will receive the data loggers 24 hours before data collection as previously established. In the pre- and post- weaning periods, data collected during 3 consecutive days (at 30 s intervals) will be considered representative of this week or month, respectively.Statistical Analysis Possible differences between the dependent variables will be determined with Proc GLIMMIX in SAS. The hair coat will be considered a fixed effect, while the animal's identification will be considered a random effect. The possible differences in the incidence of health problems between hair coat type groups and the association between these problems and the growth and feeding activity will be assessed by the Chi- square test with Proc FREQ in SAS. The relationship between the dependent variables through time will be evaluated with Proc CORR and REG in SAS.