Biomedical subjects

B D Lott

Publications and source records attributed to B D Lott.

At least 19 recordsLinked to original sources

PubMed1996

The effects of nonautoclaved and autoclaved water-soluble wheat extracts on the growth of Clostridium perfringens.

Clostridium perfringens is the causative agent of necrotic enteritis, a commonly diagnosed disease in chickens that is also observed in turkeys and geese. Two trials were conducted to determine the in vitro effect of filter-sterilized, water-soluble wheat extracts on the growth of C. perfringens. The extracts were either nonautoclaved or autoclaved at 121 C for 40 min and were used to reconstitute thioglycolate broth media. Results of this study suggest that growth of C. perfringens is suppressed in vitro by inclusion of either extract. Glycosyl composition analysis revealed no significant differences in arabinose, xylose, or mannose content between the nonautoclaved and autoclaved extracts. Galactose, glucose, and total glycosyl content were significantly higher in the nonautoclaved extract.

Animals↗

PubMed1994

Acute heat acclimation and kidney function in broilers.

Broilers previously exposed to high environmental temperatures (heat-acclimated) are more resistant to heat stress and consume more water during heat stress than nonacclimated controls. Two experiments were conducted to determine whether heat-acclimated broilers conserve body water by reducing urine and solute (Na) excretion. In the first experiment, renal function studies were conducted at an ambient temperature (Ta) of approximately 21 C using anesthetized 7-wk-old male broilers. Control birds reared at a constant Ta of 24 C (Group N: noncycled Ta) were compared with birds that had been heat-acclimated by exposure for 3 to 6 d to a daily sinusoidal cycle of 24 to 35 to 24 C (Group C: cycled Ta). In the second experiment, renal function studies were conducted on anesthetized 5-wk-old control and heat-acclimated male broilers while they were exposed to a Ta of 21 C (Ambient Ta: Groups NA, CA), or to a Ta of 32 C (High Ta: Groups NH, CH). When high intravenous infusion rates (.37 mL/kg body mass per min) were used to simulate the volume expansion caused by thermogenic polydipsia, urine flow rates were significantly lower in Groups C and CA than in Groups N and NA, osmolal clearances were lower in Groups CA and CH than in Groups NA and NH, and all heat-acclimated groups in both experiments (Groups C, CA, CH) had significantly lower glomerular filtration rates (GFR), filtered loads of Na, and tubular Na reabsorption rates than the respective control groups (Groups N, NA, NH). These changes in kidney function potentially would minimize urinary fluid and solute loss when heat-acclimated broilers consume large quantities of water to support evaporative cooling. Reductions in GFR, filtered loads of Na, and tubular Na reabsorption rates also may help heat-acclimated broilers reduce the metabolic heat load associated with active (energy requiring) recovery of solute (Na) from the glomerular ultrafiltrate.

Acclimatization↗

PubMed1994

Effects of light and temperature on anticipatory feeding by broilers.

The objective of this research was to determine the effects of daily cycles of light intensity and temperature on anticipatory feeding by broilers. Broilers were maintained on litter in environmental chambers with feed provided for 12 h/d. Feed consumption was recorded by computer every 30 min and summarized for 2- and 24-h periods. In Trial 1, lighting was at 16 lx for 12 h and at 94 lx for 12 h each day. Feed was provided either during the 16- or 94-lx period. Broilers consumed more feed at the onset of feeding and at the end of the feeding period than at other times in both treatments. In Trials 2 and 3, the chamber temperature was cycled such that a 12-h feeding period was provided at either 32 or 16 C. Broilers consumed more feed at the onset of feeding than at other times but did not increase consumption at the end of the feeding period. The results indicate anticipatory feeding is enabled by cyclic lighting intensity but not by cyclic temperature. In Trial 4, the light intensity and temperature were cyclic. Feed was provided during high light intensity and at maximum temperatures. Feed consumption increased when temperature was declining, indicating broilers responded to the reduced temperature. The results show that a period of darkness is not required for anticipatory feeding and that environmental temperatures and lighting typical of curtain-sided broiler houses alter feed consumption patterns.

Animals↗

PubMed1992

Feed and water consumption patterns of broilers at high environmental temperatures.

Broilers were reared on litter to determine the effect of cyclic environmental temperatures on feed and water consumption patterns. The temperatures were constant at 24 C for several days before cyclic temperatures were started. Control broilers continued at 24 C but the treatment was a daily 24-35-24 C cycle for 3 days. Broilers that were 5, 6, or 7 wk old consumed as much feed or water the 1st day of the cycle as on the succeeding days. Feed and water consumption were determined for 6-h periods each day beginning at minimum temperature with two periods during rising temperature and two periods during declining temperature. Feed consumption was depressed when the temperatures were declining. Water consumption increased during the 12 h when the temperature was maximum. At 7 wk, water consumption was greater for broilers on the cyclic temperature for each 6-h period except for the period of temperature decline immediately preceding the minimum temperature. Broilers exposed to the 3 days of cyclic temperatures consumed more water than controls during a subsequent exposure to temperatures up to 40.8 C. The data show that the increased water consumption and decreased feed consumption observed due to high, cyclic temperatures arise from changes that occur during some times of the day and no changes occur during other times. The increase in water consumption precedes the reduction in feed consumption.

Animals↗

PubMed1992

The effect of temperature, dietary energy level, and corn particle size on broiler performance.

Experiments were conducted to study the effect on broiler performance of grinding corn with different hammer mill screen openings (HMSO). Corn for Trials 1 and 2 was ground through HMSO of 3.18 or 9.59 mm and broilers were grown at 15.5 and 26.6 C in Trial 1 and at 26.6 C in Trial 2. Dietary energy levels used from 22 to 42 days were 3,050 and 3,230 kcal ME/kg for Trial 1 and 3,230 and 3,330 kcal ME/kg in Trial 2. In all starter and finisher diets, lysine and sulphur amino acid concentrations were similar on a megacalorie basis. In Trials 3 and 4, HMSO were 3.18, 4.76, 6.35, and 7.94 mm. Corn ground through a HMSO of 9.59 mm significantly reduced body weight and feed:gain ratio in Trials 1 and 2 at 21 days as compared with corn ground through an HMSO of 3.18 mm. At 42 days, body weights were reduced when corn was ground through 9.59- and 3.18-mm HMSO for the starter and finisher diets, respectively, as compared with those fed with the corn ground through a 3.18-mm HMSO in the starter diet. In Trials 3 and 4, significant differences in body weight and feed:gain ratios at 21 days were not noted for feed containing corn ground through an HMSO of 3.18, 4.76, 6.35, or 7.94 mm.

Animal Feed↗

PubMed1992

Effect of periodic feeding and photoperiod on anticipation of feed withdrawal.

Broiler chicks obtained from a commercial hatchery were reared on litter in environmental chambers. The rearing temperature was 32 C initially, and reduced 2,8 C/wk until 24 C was reached. Water was available for ad libitum intake. The treatments began at 7 days in Trial 1 and at 8 days in Trial 2, during which feed and water consumption were recorded by computer every 30 min and summarized for 2- and 24-h periods until each trial was completed. In Trial 1, the treatments were: 1) continuous light with feed available 12 h/day; and 2) 12 h light (L):12 h dark (D) with feed available for ad libitum consumption for 1 wk and unavailable thereafter during darkness. In Trial 2, the treatments were 1) 14L:10D; 2) 10L:14D; and 3) continuous light. During the treatments, no feed was provided during darkness and only for 12 h/day during continuous light. At 29 days, feeding and lighting were again continuously provided until the trial ended at 33 days. Broilers were able to anticipate the period of feed unavailability when it coincided with darkness. They were unable to anticipate the period when feed was unavailable if they were in continuous light. Continuously lighted broilers consumed more feed at the onset of the feeding period than did the broilers in light:dark cycles. Periodically lighted broilers consumed more feed at the end than at the onset of the feeding period. Resumption of continuous feeding occurred more quickly for continuously lighted broilers than for those previously on light:dark cycles. The data indicate that the internal clock that permits broilers to anticipate recurring periods of feed unavailability depends on a daily period of darkness.

Animals↗

PubMed1991

The effect of feed intake on body temperature and water consumption of male broilers during heat exposure.

Two trials were conducted to study the effect of feed intake on rectal temperature and water consumption of acclimated and unacclimated broilers during heat exposure. Male broiler chicks, 100 per trial, were raised as one group to 29 days for Trial 1 and 36 days for Trial 2. The birds were moved to environmental chambers and 50 per trial were acclimated by being subjected to 3 consecutive days of 24 C, 35 C, 24 C cyclic temperature. After acclimation, the birds were exposed to a linear change in temperature from 24 to 41 C over 3 h with a constant 10 C dewpoint, starting at 0800 h on Day 34 for Trial 1 and on Day 41 for Trial 2. The feeding schedule for the day of the heat exposure was as follows. For the feed group, feed was removed from the birds at 0400 h and placed back at 0700 h. For the no feed group, feed was removed at 0700 h. At 0800 h, feed was removed from all birds but water was accessible throughout the heat exposure. Acclimated and unacclimated birds given access to feed for 1 h before a heat exposure consumed 60 and 50 mL of water per broiler, respectively, during the heat exposure. However, for broilers not receiving feed, the water consumption was 58 and 30 mL per broiler, respectively. Acclimated and unacclimated broilers given access to feed had similar body temperatures, but the acclimated broilers not receiving feed had a significantly lower ending rectal temperature than the unacclimated group.

Animals↗

PubMed1990

The effect of light and environmental temperature on broiler digestive tract contents after feed withdrawal.

Contamination from the digestive tract is a persistent problem in broiler processing. Two experiments were conducted to determine the effects of lighting and environmental temperature on quantity of crop, gizzard, and small intestine contents during feed withdrawal. Broilers were on litter with a feeding regimen of 1.5 h on feed and 4.5 h off feed for 1 or 2 days. The withdrawal period began at the end of a 1.5-h feeding period. In the first experiment, broilers were cooped or left on the floor with and without lights. Crop contents of lighted broilers at 21 C were reduced 2 h after feed withdrawal for broilers on litter and in coops. In another experiment, broilers on litter were maintained at 18 and 27 C in light or in darkness. Lighting reduced crop contents 4 h after feed withdrawal but increased the contents of the small intestine 2 h after feed withdrawal at both temperatures. These results indicate that crop clearance is improved by lighting both before and after cooping.

Animals↗

PubMed1988

Weight gain of summer-reared egg-type pullets fed pellets versus mash.

In an attempt to increase weight gain of egg-type pullets reared under high summer temperatures, pullets were fed feed in either pellet or mash form. Under high temperature rearing conditions, pelleting the diet did not significantly increase 12 to 20-wk body weight gain when compared to effects of the diet fed in mash form. Under a moderate temperature regimen (21 C), pelleting the diet did significantly increase 12 to 20-wk body weight gain in contrast to the effects of the diet fed in mash form.

Animal Feed↗

PubMed1988

Position of Meckel's diverticulum in broiler-type chickens.

In each of three trials broiler-type chickens were used to determine whether Meckel's diverticulum resides in a constant position along the intestinal tract. Chickens were provided a basal diet ad libitum through 49 (Trials 2 and 3) or 52 days of age (Trial 1). Body weight and total intestine length as well as the lengths of the intestine from the gizzard to Meckel's diverticulum (GMD) and from Meckel's diverticulum (MD) to the cecal openings (MDC) were then recorded. When intestine length was expressed as a percentage of body weight, significant differences were noted between sexes. However, no significant differences were observed between sexes for either GMD or MDC relative to total intestinal length. Results of this study indicate that MD resides in a constant position along the length of the intestinal tract. This constancy of position supports the use of MD as a boundary point of the intestine.

Animals↗

PubMed1987

Effect of beak trimming on body weight and feed intake of egg-type pullets fed pellets or mash.

Pelleted and mash feed were provided in each of two trials. In the first trial, it was noted that the pullets did not eat the feed that was offered in pellet form. Type of beak trimming appeared to be involved in lowering feed intake. The second trial demonstrated that pullets with either the top beak or both beaks trimmed (block cut) approximately 2 mm from the nostril when offered pellets or mash did not eat feed in pellet form as readily as that in mash form.

Animal Feed↗

PubMed1985

Noted difference in the digestive system in caged and floor-reared commercial egg-type pullets.

Two trials were conducted with Single Comb White Leghorn pullets reared from 0 to 19 weeks of age in cages and on litter at the same environmental temperature. Samples were obtained to determine if digestive system differences existed. Criteria measured were gizzard weight and intestine length. Results showed that floor-reared pullets had heavier gizzards with longer intestines than cage-reared pullets. The difference may be caused by consumption of litter by the floor-reared birds.

Animals↗

PubMed1985

Age and dietary energy effect on broiler abdominal fat deposition.

Three trials were conducted to determine when abdominal fat is deposited in relation to age and dietary energy level for broilers. Results show that the amount of abdominal fat as a percentage of body weight increased as age (36 to 54 days) and dietary energy level (3100 to 3325 metabolizable energy kcal/kg) increased. During the 36 to 54-day period, the weight of the broilers increased 75% for males and 72% for females. During the 36 to 54-day period, abdominal fat expressed as a percentage of body weight increased 23% for males and 38% for females.

Abdomen↗

PubMed1984

Effect of atmospheric ammonia on pullets at point of lay.

Results obtained show that pullets exposed to 200 ppm atmospheric ammonia for 17 days had a reduced feed intake and reduced growth rate when compared to controls. After the ammonia exposure period at point of lay, percent egg production was less and mortality greater for the ammonia exposed group versus the controls.

Air Pollutants↗

PubMed1984

Effect of differing temperature cycles on broiler performance.

Commercial male broilers were used in five trials conducted to determine whether lowering the temperature during the cool portion of the 24-hr period in summer affected broiler performance. Treatments used were 24-hr linear temperature cycles ranging from a high of 35 C to a low of either 26.7 or 21.1 C. Results obtained showed that lowering the low portion of the temperature cycle from 26.7 to 21.1 C during the 24-hr period significantly increased broiler body weight at 48 days of age.

Animal Feed↗

PubMed1984

The effects of feed form, protein profile, energy level, and gender on broiler performance in warm (26.7 C) environments.

Two dietary energy levels, 3032 and 3109 kcal ME/kg, and four protein levels of approximately 17, 18, 19 and 20%, were used to formulate eight grower-finisher rations used in four feeding regimens used in both mass and crumble form fed to broilers in a warm (26.7 C) environment. The protein levels were established by specific lysine: energy ratios with methionine plus cystine at a constant percentage of lysine. Best overall broiler performance was obtained with a feeding regimen using the higher energy level with high-protein profile in crumble form; feed conversion for this regimen was improved 5.4% and body weight 3.2% over the poorest performing diet, which was the lower energy diet with low-protein profile in mash form. Overall, crumbling improved feed conversion 1.5% and increased body weight 2.2%, the high-protein profile improved feed conversion 2.0%, and increasing metabolizable energy from 3032 to 3109 kcal/kg improved feed conversion 2.2%. Feed conversion for males was 3.3% better than for females.

Animal Feed↗

PubMed1983

The effects of temperature and age on body weight and feed efficiency of broiler chickens.

Mixed sex, commercial broiler chickens were grown at three environmental temperatures: 15.6, 21.1, and 26.7 C. Starting at 35 days, body weights and feed conversions were measured at 3- to 5-day intervals to 55 days of age. Both body weights and feed conversions were linear with age over the time range indicated. The growth rates at 26.7 C were 6% less at 35 days and 10% less at 55 days than at 15.6 C. When equated for body weight differences, there was no difference in feed conversion between broilers grown at 21.1 and 26.7 C. Birds grown at 15.6 C consumed more feed per unit of weight than at the other two temperatures. At 49 days of age, the birds grown at 15.6 C required 16% more feed than those grown at 26.7 C; however, when weights were equated at 2000 g, those grown at 15.6 C required only 3% more feed than those grown at 26.7 C.

Aging↗

PubMed1983

The effect of dietary energy level and broiler body weight on abdominal fat.

Utilizing a moderate rearing temperature regimen, two trials were conducted to determine the effect of dietary energy level on the amount of abdominal fat deposited when broilers are grown to equal body weight by varying growth time. The most abdominal fat (2.29% average of live weight for male and females) was produced by broilers offered a diet calculated to contain 3325 ME kcal/kg. The least amount of abdominal fat (1.92% average of live weight for male and females) was produced by broilers offered diets calculated to contain 3100 and 3175 metabolizable energy (ME) kcal/kg. In one additional day (48 vs. 47 days) the growth of the broilers offered diets calculated to contain 3100 and 3175 ME kcal/kg equalled that of broilers offered diets calculated to contain 3250 and 3325 ME kcal/kg. Feed conversion (g feed/g live weight) significantly decreased as dietary energy level increased. Three additional trials were conducted to determine when abdominal fat is deposited in relation to age and weight. It was found that male broilers offered diets calculated to contain 3325 ME kcal/kg had as much abdominal fat when expressed as a percent of body weight at 40 days of age as they did at 53 days of age.

Abdomen↗