G E Selk

Oklahoma State University - Stillwater, Stillwater, OK, United States

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Publications (7)2.09 Total impact

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    ABSTRACT: An expert system shell, written in C, served as the inference engine for a prototypical knowledge base developed to recommend whether to keep or cull commercial beef cows. A reproduction specialist was interviewed and 20 rules reflecting his knowledge were programmed in an expert system knowledge base. Rules contained knowledge relating the cow's age, body condition score, calving difficulty, structural correctness, health and previous reproductive and weaning weight performance to desirability of culling or keeping the cow. Cows are classified into three categories, cull, keep or rank. The net present value of those classified in rank is estimated based on expected future performance and salvage value by calling a cow herd simulation model, also written in C, from within the expert system. The cow with the lowest net present value is culled first when additional cows are to be culled. The system can be either integrated with a computer database or interactive, querying a cow data file or the user for information about each cow, making a decision, and responding with its recommendation. Evaluation revealed close correspondence between the expert's and the system's decisions. Any C function can be called in the rule base, thus allowing the integration of any computer program coded in C with the shell.
    Computers and Electronics in Agriculture. 01/1990;
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    ABSTRACT: A 5-yr study involving 45 to 78 pregnant Hereford range cows each year evaluated relationships among prepartum nutrition, body condition scores, BW changes and reproductive performance. Four prepartum nutritional treatments were imposed. One group of cows were fed to maintain (M) their November BW until calving in March and April. The other three groups of cows were fed to lose about 5% of their November BW by 8 wk before parturition, then to maintain BW (LM), lose an additional 5% of their BW (LL) or gain 5% of their BW (LG). After calving, all cows were fed to maintain BW. Body condition scores and BW were recorded every 14 d throughout the trial. Linear regression analyses were conducted to examine treatment effects on BW, body condition score and measures of reproductive performance. A discriminant analysis was performed on pregnancy rate and percentage of cows with ovarian luteal activity by 85 d after parturition. The M cows had a greater pregnancy rate (71%) than cows on other treatment groups. The LL cows had a reduced pregnancy rate (42%) compared with LM (51%) and LG (58%) cows. Prepartum nutritional treatment did not affect the days from parturition to conception. Precalving body condition score and November to January BW changes influenced pregnancy rate (P less than .001). A cubic response curve described the relationship between pregnancy rate and precalving body condition score for cows with condition scores of 3 through 7.(ABSTRACT TRUNCATED AT 250 WORDS)
    Journal of Animal Science 01/1989; 66(12):3153-9. · 2.09 Impact Factor
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    ABSTRACT: Story in Brief This experiment was conducted to study the effects of increasing levels of undegradable intake protein (UIP; escape/bypass protein) during early lactation on the performance of fall-calving beef cows (1997, n=58; 1998, n=54). Angus x Hereford cows grazing dormant tall grass prairie were fed supplements formulated to supply adequate degradable intake protein and increasing amounts of undegradable intake protein (142, 196, 248, and 301 g/d). Cows were group fed 3 lb of supplement daily for approximately 130 d. In 1997, cow weight and condition loss was minimized with increasing UIP supplementation, up to 248 g UIP/d, however, UIP in excess of this amount increased weight loss. During 1998, increasing levels of UIP was associated with a linear decrease in weight loss. All cows returned to similar weights by weaning, in both years. Greatest body condition losses were associated with 142 and 301 g UIP/d, regardless of year. Supplemental treatment of the cows did not influence calf weight gains. These data indicate that up to 250 g of supplemental UIP/d is effective in reducing weight and body condition loss in lactating beef cows grazing dormant native tall grass pasture. Effects of supplemental UIP beyond 250 g UIP/d may be dependent on year to year variation in forage characteristics and/or animal requirements.
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    ABSTRACT: Story in Brief Fifty-six mature beef cows were used in a 2 x 2 factorial design to identify effects of level of cow supplementation and creep feeding on cow and calf performance. Angus and Hereford x Angus cows calved during September and October and grazed abundant tall grass prairie throughout the experiment. Cow/calf pairs were assigned to one of eight pastures based on treatment and calving date block. Treatments were: 1) 2 lb of 40% CP supplement with no creep feed (LN); 2) 6 lb of 20% CP supplement with no creep feed (HN); 3) 6 lb of 20% CP supplement with calves having ad libitum access to creep feed (HC); and 4) 2 lb of 40% CP supplement with creep feed (LC). Treatments were initiated on January 7, after the breeding season had ended, and continued through April 14. There were no significant cow nutrition x creep feed interactions. Supplement treatments did not influence cow weight or body condition score (BCS) change during winter or spring. Calf weight gain from January to April (while receiving creep) was increased due to creep feeding (125 vs 180 lb). Creep feeding fall-born calves had no effect on cow weight and BCS change. Sixty-two percent of the additional weight gain from winter creep feeding was retained through weaning. Creep fed calves from low nutrition level cows had enough additional weaning weight to offset the additional feed costs and return an additional $6.30 per calf. Non creep fed calves from the high nutrition cows tended to wean at heavier weights.
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    ABSTRACT: Story in Brief A two-year study was conducted to identify effects of level of cow supplementation and creep feeding on cow and calf performance. One hundred and seven fall calving Angus and Hereford x Angus cows calved during September and October and grazed abundant tall grass prairie throughout the experiment. Treatments were initiated in early January, after the breeding season had ended, and continued through April. Pairs were assigned to one of four treatments based on calving date and calf gender. Treatments were: 1) 2 lb of 40% crude protein supplement with no creep feed; 2) 6 lb of 20% crude protein supplement with no creep feed; 3) 2 lb of 40% crude protein supplement with calves having ad libitum access to creep feed; and 4) 6 lb of 20% crude protein supplement with creep feed. Creep feeding calves did not influence cow weight or body condition score change during winter or spring. Cows fed the higher level of winter supplement lost slightly less weight during winter and gained slightly more weight during spring and early summer grazing. Creep feeding resulted in increased calf weight gain from January to April (91 and 69 pounds for calves nursing cows receiving the restricted and high level of winter supplement, respectively). Seventy nine percent of the additional weight gain from winter creep feeding was retained through weaning.