Source: MICHIGAN STATE UNIV submitted to
IMPACT OF GROWTH AND LACTATION ON THE NUTRITIONAL NEEDS AND ECONOMIC VIABILITY OF THE SHEEP FLOCK
 
PROJECT DIRECTOR: Benson, M.
 
PERFORMING ORGANIZATION
ANIMAL SCIENCE
MICHIGAN STATE UNIV
EAST LANSING,MI 48824
 
NON TECHNICAL SUMMARY:
 
OBJECTIVES: 1)To evaluate the effect of increasing carcass weight, loin eye area and carcass leanness on ewe productivity, lamb performance and the economic viability of a commercial flock. 2)To evaluate nutrient utilization of lactating ewes and quantify the costs of milk production and costs of suckling lamb gain for optimizing lamb production in farm flocks.
 
APPROACH: Crossbred ewes will be mated to Suffolk sires that vary in degree of muscling. Male offspring will be castrated and grown to a market weight of 62 kg. Performance and carcass data will be collected. Ewe lambs will be bred at 7 months of age and reproductive performance evaluated. Comparisons of weight of lamb marketed per ewe, cost of gain, and identification of economically optimum market weight will be made. Milk prodcution will be determined using 15-30 twin-rearing ewes. The efficiency with which ewes convert consumed nutrients into milk will be determined by comparing nutrient intake to nutrient deposition in the milk. Lamb gain attributed to milk production of the ewe will be quantified. The efficiency with which suckling lambs convert consumed nutrients from milk into lamb gain will be determined.
 
CRIS NUMBER: 0180728 SUBFILE: CRIS
PROJECT NUMBER: MICL01913 SPONSOR AGENCY: CSREES
PROJECT TYPE: HATCH PROJECT STATUS: TERMINATED MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Nov 1, 1998 TERMINATION DATE: Dec 31, 2003

GRANT PROGRAM: (N/A)
GRANT PROGRAM AREA: (N/A)

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
302361010102.2100%

CLASSIFICATION HEADINGS
KA302 - Nutrient Utilization in Animals
S3610 - Sheep, live animal
F1010 - Nutrition and metabolism
G2.2 - Increase Efficiency of Production and Marketing Systems


RESEARCH EFFORT CATEGORIES
BASIC (N/A)%
APPLIED 100%
DEVELOPMENTAL (N/A)%

KEYWORDS: lactation; sheep; animal growth; animal nutrition; nutrient requirements; economic viability; ewes; lambs; milk production; carcass weight; lean meat; carcass evaluation; nutrient utilization; costs; livestock production; optimization; performance evaluation; profitability; weight gains

PROGRESS: Nov 1, 1998 TO Dec 31, 2003
The major results from this project designed to enhance productivity and viability of commercial farm flock sheep enterprises are summarized by the following. A within-flock sire section strategy was designed to increase flock productivity for the economically important traits. Ultrasound technology using a Classic Scanner 200 and 18 cm Animal Science probe for measuring loin eye area, loin eye depth and backfat was evaluated as a tool to supplement carcass data and evaluate muscling and fat characteristics in live animals. Accuracy and precision of ultrasound measurements using different probes were compared to actual carcass measurements at the time of harvest. Correlations of ultrasound measurement to carcass measurements of .30 and .57 were found using the cattle and swine probes, respectively. It was concluded that selection strategies should not yet rely on this technology for predictable results in live animals. Within a 75-ewe commercial flock, a breeding selection strategy consisted of selecting within-flock replacement sires based on loin eye area. From 1999 through 2001, loin eye area of unselected progeny increased from 16.8 square cm to 18.2 square cm (8.3%) as determined by actual carcass measurements. Selection pressure for this economically important trait increased carcass merit of offspring in flocks using this strategy. Cost of gain analyses found that lambs started on trial at 25 or 35 kg was reduced 11.9 and 20 percent, respectively, by feeding a concentrate-based diet compared to a forage based diet. Cost of gain differences due to dietary treatment were attributed to treatment effects on both rate of gain and feed intake. A second emphasis of this project evaluated nutrient utilization and costs of suckling lamb gain. Daily milk production data of individual ewes were used to assess lamb intakes. Dry matter intakes (DMI), expressed as percent of bodyweight, of the pre-weaned lambs were determined from dry matter content of the estimated milk intake and were similar to National Research Council - Sheep (NRC) estimates for DMI in lambs weighing 10 to 20 kg. As expected, DMI expressed as a percent of bodyweight, declined with increasing age and weight. Crude protein intakes were determined from milk production and milk protein content. Estimated crude protein intakes of lambs were less than suggested NRC requirements for crude protein for the rates of gain observed. Lambs were more efficient in their use of crude protein than current recommended requirements assume. Based on energy composition of the milk and daily intake, energy intakes were greater than NRC requirements at the rates of gain observed, especially at light weights and ages less than 42 days. Neither estimates of metabolizable energy intake nor net energy intake accurately predicted observed daily gains until after 42 days of age. The efficiency with which suckling lambs convert nutrients into gain was an important factor to recognize when strategizing to optimize lamb production

IMPACT: 1998-11-01 TO 2003-12-31 Within-flock selection and management strategies by which sheep producers can increase the quality and value of lambs produced and therefore improve their likelihood of future economic success and viability was defined. By applying selection pressure, loin eye area increased more that 4 percent annually in the offspring. Increasing the size of a high value portion of the lamb carcass increases carcass merit and value. This information has caused producers to evaluate their sire selection strategies and provided further incentive for producers to continue pushing for value-based marketing options. Quantifying ewe milk production and suckling lamb growth and performance has provided information necessary to more accurately assess nutritional needs and management strategies during lactation, the most demanding stage of ewe production. This work has been cited in national industry publications and has identified categories of nutrient requirements for suckling lambs that need to be re-evaluated.

PUBLICATION INFORMATION: 1998-11-01 TO 2003-12-31
No publications reported this period

PROJECT CONTACT INFORMATION
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