R. Dean Boyd | University of Wisconsin Stevens Point (original) (raw)
Papers by R. Dean Boyd
The effect of colostrum on endocrine and metabolic factors affecting glucose ho-meostasis was eva... more The effect of colostrum on endocrine and metabolic factors affecting glucose ho-meostasis was evaluated in 60 neonatal pigs that were fasted, fed (nursed ad libitum) or limit-fed colostrum (25% ad libitum, 4-hr interval feeding). Plasma acquired at birth (tO), and after 10, 20 and 30 hr (tlO, t20 and t30, respectively) was analyzed for glucose, non-esterified fatty acids (NEFA), and the glucoregulatory hormones-insulin, glucagon, cortisol, growth hormone and catecholamines. The concentration of glucose and NEFA was similar among treatment groups at birth and increased in proportion to the quantity of colostrum consumed. Pigs fed ad libitum achieved and maintained a higher (>__40%; P<.O1) glucose concentration when compared to fasted neonates. Limit-fed counterparts also achieved and maintained higher levels, with glucose concentration being approximately 20% higher throughout (P<.05). Fed pigs maintained NEFA concentrations which were approximately 2.5-fold to 4-fold greater than that of fasted pigs (P<.05). Likewise, limit-fed pigs tended (P=. 19) to have elevated NEFA concentrations and a lower (P<.05) insulin:glucagon molar ratio. An inverse relationship was observed between colostrum intake and plasma concentrations of cortisol and growth hormone. Concentrations of epinephrine and norepinephrine tended (P>. 1 O) to be elevated in fed pigs, relative to those of fasted counterparts. Provision of even limited quantities of colostrum is therefore beneficial to the glucoregulatory response in newborn pigs.
Journal of Animal Science, 2007
Lactation feed disappearance and weaning to estrus interval for sows fed spray-dried ABSTRACT: Fo... more Lactation feed disappearance and weaning to estrus interval for sows fed spray-dried ABSTRACT: Four experiments involving 265, 410, 894, and 554 sows (Exp. 1 to 4, respectively) were conducted to determine the effect of spray-dried plasma (SDP) at 0 or 0.25% (Exp. 1 and 2) and 0 or 0.50% (Exp. 3 and 4) in lactation diets on average daily feed disappearance (FD), sum of sow BW, fetal and placental loss from d 110 gestation to weaning (SWL), litter size at weaning, litter weight at weaning, and average days from weaning to first estrus (WEI). Experiments 1, 3, and 4 were conducted during summer months, and Exp. 2 was conducted during fall to winter months. Experiment 1 used only parity 1 and parity 2 sows and Exp. 4 used only mature (>2 parities) sows, whereas Exp. 2 and 3 used all parity groups. Sows fed SDP in Exp. 1 had increased (P < 0.01) FD and a tendency for reduced (P = 0.06) SWL and WEI (P = 0.06). Sows fed SDP in Exp. 2 had a tendency for increased (P = 0.09) sow BW at weaning and reduced (P = 0.09) SWL, whereas other variables were not different between diets. Parity 1 and 2 sows fed SDP in Exp. 3 had increased (P < 0.01) FD,
SUMMARY Two experiments were conducted to deter- mine the effect of level and source of energy fe... more SUMMARY Two experiments were conducted to deter- mine the effect of level and source of energy fed to sows prior to parturition and during lac- tation on birth weight, gain, and survival of pig- lets and fat content of the dam&amp;amp;amp;amp;amp;amp;amp;amp;#39;s milk. The first experiment involved 30 gilts and nine sows. The gestation control diet, providing 5,750 kcal of metabolizable
Domestic Animal Endocrinology, 1998
Porcine somatotropin (pST) administration reduces the sensitivity of pigs to insulin, and after s... more Porcine somatotropin (pST) administration reduces the sensitivity of pigs to insulin, and after several days of treatment, it alters baseline circulating concentrations of pST, insulin, glucose, and other metabolites. The length of time required to develop this reduction in whole-body insulin sensitivity has not been established. To investigate this, eight castrate pigs received daily injections of either recombinant pST (120 g/kg BW) or excipient. Intravenous insulin tolerance tests (1.0 g/kg BW) were done before the first pST injection (Day 0) and on Day l, 3, 5, and 8 of pST treatment. Control animals had insulin tolerance tests on Day 0 and again on Day 8 of treatment. By Day 8, the glucose response to the insulin tolerance tests in pST-treated pigs was 45% of the response of the control group (P Ͻ 0.01). Glucose response areas between Day l, 3, 5, and 8 of pST treatment were not different (P Ͼ 0.10). The maximum effect of pST on glucose response to insulin was achieved by Day 1. Therefore, factors responsible for the development of reduced whole-body insulin sensitivity in pST-treated pigs are fully expressed within 21 hr of the initial pST treatment.
Nutrient Uptake and Endocrine Regulation of Milk Synthesis by Mammary Tissue of 1995, 73:36-56. J... more Nutrient Uptake and Endocrine Regulation of Milk Synthesis by Mammary Tissue of 1995, 73:36-56. J ANIM SCI http://jas.fass.org/content/73/suppl_2/36.citation the World Wide Web at:
This study was conducted to determine the effects of exogenous porcine somatotropin (pST) on the ... more This study was conducted to determine the effects of exogenous porcine somatotropin (pST) on the dietary lysine requirement and efficiency of absorbed lysine utilization for pigs during the 20-to 60-kg phase of growth. Seventy-two crossbred pigs (20 ± 0.7 kg body wt) received daily intramuscular injections of either ex cipient (0 dose) or pST (150 /tg/kg body wt) and were fed diets in which protein and lysine concentrations ranged from 6.4 to 23.5 g/100 g diet and from 0.40 to 1.48 g/100 g diet, respectively. Nutrient density was altered to compensate for reduced feed intake with pST, but diets were approximately isocaloric. Rate and effi ciency of gain and whole-body protein accretion rate exhibited a dose-response improvement (P < 0.01) to increases in dietary protein for both excipient and pSTtreated pigs. Pigs receiving pST grew more rapidly and more efficiently than control counterparts (P < 0.01). Treatment with pST improved the rate of protein accretion (P < 0.01) at all but the lowest level of dietary protein. The net lysine utilization for lysine accretion and maintenance was 0.46 for control pigs and 0.57 for pigs receiving pST, a 24% improvement in the efficiency. Thus, treatment with pST increased the maximum rate of protein accretion as well as the partial efficiency with which dietary lysine is used for protein accretion. Conse quently, only a 9% increase in dietary lysine was re quired to maximize protein deposition in pST-treated pigs, because the metabolic efficiency of lysine utili zation was improved.
A total of 48 neonatal pigs were used to determine whether intubation with colostrum or medium-ch... more A total of 48 neonatal pigs were used to determine whether intubation with colostrum or medium-chain triglyceride (MCT) would enhance glucose homeostasis and survival. Pigs were removed from the sow prior to nursing and alloted to three treatment groups. Fasted pigs received only water for 30 h, whereas those allotted to supplemented groups received either 30 ml of colostrum or 15 ml of MCT at 6 and 16 h after birth (t6 and t16). Supplementation with MCT (t6) resulted in a 2.4-fold elevation in plasma non-esterified fatty acid (NEFA) concentration compared with fasted pigs (260 vs 109 microEq/liter at t8; P less than .05). This difference increased following the second MCT dose (436 vs 117 microEq/liter at t18; P less than .05). Colostrum supplementation also elevated plasma NEFA (201 and 259 microEq/liter at t8 and t18, respectively); however, less triglyceride fatty acid was presented via colostrum compared with MCT. Supplementation with MCT resulted in a greater increase in plasma glucose concentration, relative to fasting levels (75 vs 56 mg/ml at t8; 76 vs 62 mg/ml at t18), than was obtained with colostrum (68 and 65 mg/ml at t8 and t18, respectively). Residual effects of supplementation to t30 were evident for both MCT and colostrum pigs in NEFA levels, but only the MCT group had a greater (P less than .05) concentration of plasma glucose at t30 compared with the fasted group (63 vs 49; P less than .05). This regimen of MCT supplementation was employed in an experiment with nursing pigs to determine whether MCT would improve glucose status and survival of less-competitive pigs.(ABSTRACT TRUNCATED AT 250 WORDS)
The shift in nutrient partitioning induced by porcine somatotropin (pST) is accompanied by a decr... more The shift in nutrient partitioning induced by porcine somatotropin (pST) is accompanied by a decrease in insulin sensitivity for whole-body glucose uptake. The relative contribution of metabolic changes in the hindlimb was investigated in eight pigs (55 kg) that had received recombinant pST (120 ng/kg) or excipient (control) for 7 d. Uptake of metabolites by the hindlimb was measured under basal conditions and during hyperinsulinemic-euglycemic clamps at low [14 ng/ (kg.min)] and high [360 ng/(kg-min)] insulin infusion rates. Dextrose infusion rate required to maintain euglycemia was used as an index of whole-body glucose uptake in response to exogenous insulin. Effects of pST on hindlimb and whole-body glucose uptake were evident only at physiological levels of insulin (basal and low insulin infusion rate). During the low rate of insulin in fusion, dextrose infusion rate was 79% lower for pSTtreated pigs and glucose uptake by the hindlimb was 59% lower compared with control pigs. The decrease in glucose uptake by the hindlimb was entirely accounted for by the estimated reduction in glucose utilization by adipose tissue of the hindlimb. Glucose:oxygen quo tients were reduced during basal (57%) and low insulin infusion (63%) with pST treatment, indicating a change in the pattern of substrate utilization. This is consistent with the concept that pST directs nutrients away from adipose and towards muscle growth by altering the re sponse of tissues to homeostatic signals such as in sulin. J. Nutr. 125: 125-135, 1995.
British Journal of Nutrition, 1993
Hepatocytes were isolated from sixteen fasting neonatal pigs and used in two experiments: (1) to ... more Hepatocytes were isolated from sixteen fasting neonatal pigs and used in two experiments: (1) to determine the effect of various factors on the ability for hepatic oxidation of fatty acids and (2) to clarify the relationship between fatty acid oxidation and glucose synthesis. In Expt 1, newborn pigs were either fasted from birth for 24 h or allowed to suck ad lib. for 3 d followed by a 24 h fast. In the presence of pyruvate, oxidation of octanoate (2 mM) was about 30-fold greater than oleate (1 mM) regardless of age, but glucose synthesis was not enhanced beyond that observed for pyruvate alone. Inclusion of carnitine (1 mM), glucagon (100 nM) or dibutryl CAMP (50 p~) in the incubation media did not stimulate either fatty acid oxidation (octanoate or oleate) or glucose synthesis. Extending the period of fasting to 48 h (Expt 2) failed to enhance the fatty acid oxidative capacity or glucose synthesis rate. Likewise, the redox potential of the gluconeogenic substrate (lactate v. pyruvate) did not influence glucose synthesis regardless of the oxidative capacity exhibited for fatty acids. These data indicate that fatty acid oxidative capacity is not the first limiting factor to full expression of gluconeogenesis in hepatocytes isolated from fasted newborn pigs.
1985, 60:659-665. J ANIM SCI http://jas.fass.org/content/60/3/659 services, is located on the Wor... more 1985, 60:659-665. J ANIM SCI http://jas.fass.org/content/60/3/659 services, is located on the World Wide Web at:
The effect of colostrum on endocrine and metabolic factors affecting glucose ho-meostasis was eva... more The effect of colostrum on endocrine and metabolic factors affecting glucose ho-meostasis was evaluated in 60 neonatal pigs that were fasted, fed (nursed ad libitum) or limit-fed colostrum (25% ad libitum, 4-hr interval feeding). Plasma acquired at birth (tO), and after 10, 20 and 30 hr (tlO, t20 and t30, respectively) was analyzed for glucose, non-esterified fatty acids (NEFA), and the glucoregulatory hormones-insulin, glucagon, cortisol, growth hormone and catecholamines. The concentration of glucose and NEFA was similar among treatment groups at birth and increased in proportion to the quantity of colostrum consumed. Pigs fed ad libitum achieved and maintained a higher (>__40%; P<.O1) glucose concentration when compared to fasted neonates. Limit-fed counterparts also achieved and maintained higher levels, with glucose concentration being approximately 20% higher throughout (P<.05). Fed pigs maintained NEFA concentrations which were approximately 2.5-fold to 4-fold greater than that of fasted pigs (P<.05). Likewise, limit-fed pigs tended (P=. 19) to have elevated NEFA concentrations and a lower (P<.05) insulin:glucagon molar ratio. An inverse relationship was observed between colostrum intake and plasma concentrations of cortisol and growth hormone. Concentrations of epinephrine and norepinephrine tended (P>. 1 O) to be elevated in fed pigs, relative to those of fasted counterparts. Provision of even limited quantities of colostrum is therefore beneficial to the glucoregulatory response in newborn pigs.
Journal of Animal Science, 2007
Lactation feed disappearance and weaning to estrus interval for sows fed spray-dried ABSTRACT: Fo... more Lactation feed disappearance and weaning to estrus interval for sows fed spray-dried ABSTRACT: Four experiments involving 265, 410, 894, and 554 sows (Exp. 1 to 4, respectively) were conducted to determine the effect of spray-dried plasma (SDP) at 0 or 0.25% (Exp. 1 and 2) and 0 or 0.50% (Exp. 3 and 4) in lactation diets on average daily feed disappearance (FD), sum of sow BW, fetal and placental loss from d 110 gestation to weaning (SWL), litter size at weaning, litter weight at weaning, and average days from weaning to first estrus (WEI). Experiments 1, 3, and 4 were conducted during summer months, and Exp. 2 was conducted during fall to winter months. Experiment 1 used only parity 1 and parity 2 sows and Exp. 4 used only mature (>2 parities) sows, whereas Exp. 2 and 3 used all parity groups. Sows fed SDP in Exp. 1 had increased (P < 0.01) FD and a tendency for reduced (P = 0.06) SWL and WEI (P = 0.06). Sows fed SDP in Exp. 2 had a tendency for increased (P = 0.09) sow BW at weaning and reduced (P = 0.09) SWL, whereas other variables were not different between diets. Parity 1 and 2 sows fed SDP in Exp. 3 had increased (P < 0.01) FD,
SUMMARY Two experiments were conducted to deter- mine the effect of level and source of energy fe... more SUMMARY Two experiments were conducted to deter- mine the effect of level and source of energy fed to sows prior to parturition and during lac- tation on birth weight, gain, and survival of pig- lets and fat content of the dam&amp;amp;amp;amp;amp;amp;amp;amp;#39;s milk. The first experiment involved 30 gilts and nine sows. The gestation control diet, providing 5,750 kcal of metabolizable
Domestic Animal Endocrinology, 1998
Porcine somatotropin (pST) administration reduces the sensitivity of pigs to insulin, and after s... more Porcine somatotropin (pST) administration reduces the sensitivity of pigs to insulin, and after several days of treatment, it alters baseline circulating concentrations of pST, insulin, glucose, and other metabolites. The length of time required to develop this reduction in whole-body insulin sensitivity has not been established. To investigate this, eight castrate pigs received daily injections of either recombinant pST (120 g/kg BW) or excipient. Intravenous insulin tolerance tests (1.0 g/kg BW) were done before the first pST injection (Day 0) and on Day l, 3, 5, and 8 of pST treatment. Control animals had insulin tolerance tests on Day 0 and again on Day 8 of treatment. By Day 8, the glucose response to the insulin tolerance tests in pST-treated pigs was 45% of the response of the control group (P Ͻ 0.01). Glucose response areas between Day l, 3, 5, and 8 of pST treatment were not different (P Ͼ 0.10). The maximum effect of pST on glucose response to insulin was achieved by Day 1. Therefore, factors responsible for the development of reduced whole-body insulin sensitivity in pST-treated pigs are fully expressed within 21 hr of the initial pST treatment.
Nutrient Uptake and Endocrine Regulation of Milk Synthesis by Mammary Tissue of 1995, 73:36-56. J... more Nutrient Uptake and Endocrine Regulation of Milk Synthesis by Mammary Tissue of 1995, 73:36-56. J ANIM SCI http://jas.fass.org/content/73/suppl_2/36.citation the World Wide Web at:
This study was conducted to determine the effects of exogenous porcine somatotropin (pST) on the ... more This study was conducted to determine the effects of exogenous porcine somatotropin (pST) on the dietary lysine requirement and efficiency of absorbed lysine utilization for pigs during the 20-to 60-kg phase of growth. Seventy-two crossbred pigs (20 ± 0.7 kg body wt) received daily intramuscular injections of either ex cipient (0 dose) or pST (150 /tg/kg body wt) and were fed diets in which protein and lysine concentrations ranged from 6.4 to 23.5 g/100 g diet and from 0.40 to 1.48 g/100 g diet, respectively. Nutrient density was altered to compensate for reduced feed intake with pST, but diets were approximately isocaloric. Rate and effi ciency of gain and whole-body protein accretion rate exhibited a dose-response improvement (P < 0.01) to increases in dietary protein for both excipient and pSTtreated pigs. Pigs receiving pST grew more rapidly and more efficiently than control counterparts (P < 0.01). Treatment with pST improved the rate of protein accretion (P < 0.01) at all but the lowest level of dietary protein. The net lysine utilization for lysine accretion and maintenance was 0.46 for control pigs and 0.57 for pigs receiving pST, a 24% improvement in the efficiency. Thus, treatment with pST increased the maximum rate of protein accretion as well as the partial efficiency with which dietary lysine is used for protein accretion. Conse quently, only a 9% increase in dietary lysine was re quired to maximize protein deposition in pST-treated pigs, because the metabolic efficiency of lysine utili zation was improved.
A total of 48 neonatal pigs were used to determine whether intubation with colostrum or medium-ch... more A total of 48 neonatal pigs were used to determine whether intubation with colostrum or medium-chain triglyceride (MCT) would enhance glucose homeostasis and survival. Pigs were removed from the sow prior to nursing and alloted to three treatment groups. Fasted pigs received only water for 30 h, whereas those allotted to supplemented groups received either 30 ml of colostrum or 15 ml of MCT at 6 and 16 h after birth (t6 and t16). Supplementation with MCT (t6) resulted in a 2.4-fold elevation in plasma non-esterified fatty acid (NEFA) concentration compared with fasted pigs (260 vs 109 microEq/liter at t8; P less than .05). This difference increased following the second MCT dose (436 vs 117 microEq/liter at t18; P less than .05). Colostrum supplementation also elevated plasma NEFA (201 and 259 microEq/liter at t8 and t18, respectively); however, less triglyceride fatty acid was presented via colostrum compared with MCT. Supplementation with MCT resulted in a greater increase in plasma glucose concentration, relative to fasting levels (75 vs 56 mg/ml at t8; 76 vs 62 mg/ml at t18), than was obtained with colostrum (68 and 65 mg/ml at t8 and t18, respectively). Residual effects of supplementation to t30 were evident for both MCT and colostrum pigs in NEFA levels, but only the MCT group had a greater (P less than .05) concentration of plasma glucose at t30 compared with the fasted group (63 vs 49; P less than .05). This regimen of MCT supplementation was employed in an experiment with nursing pigs to determine whether MCT would improve glucose status and survival of less-competitive pigs.(ABSTRACT TRUNCATED AT 250 WORDS)
The shift in nutrient partitioning induced by porcine somatotropin (pST) is accompanied by a decr... more The shift in nutrient partitioning induced by porcine somatotropin (pST) is accompanied by a decrease in insulin sensitivity for whole-body glucose uptake. The relative contribution of metabolic changes in the hindlimb was investigated in eight pigs (55 kg) that had received recombinant pST (120 ng/kg) or excipient (control) for 7 d. Uptake of metabolites by the hindlimb was measured under basal conditions and during hyperinsulinemic-euglycemic clamps at low [14 ng/ (kg.min)] and high [360 ng/(kg-min)] insulin infusion rates. Dextrose infusion rate required to maintain euglycemia was used as an index of whole-body glucose uptake in response to exogenous insulin. Effects of pST on hindlimb and whole-body glucose uptake were evident only at physiological levels of insulin (basal and low insulin infusion rate). During the low rate of insulin in fusion, dextrose infusion rate was 79% lower for pSTtreated pigs and glucose uptake by the hindlimb was 59% lower compared with control pigs. The decrease in glucose uptake by the hindlimb was entirely accounted for by the estimated reduction in glucose utilization by adipose tissue of the hindlimb. Glucose:oxygen quo tients were reduced during basal (57%) and low insulin infusion (63%) with pST treatment, indicating a change in the pattern of substrate utilization. This is consistent with the concept that pST directs nutrients away from adipose and towards muscle growth by altering the re sponse of tissues to homeostatic signals such as in sulin. J. Nutr. 125: 125-135, 1995.
British Journal of Nutrition, 1993
Hepatocytes were isolated from sixteen fasting neonatal pigs and used in two experiments: (1) to ... more Hepatocytes were isolated from sixteen fasting neonatal pigs and used in two experiments: (1) to determine the effect of various factors on the ability for hepatic oxidation of fatty acids and (2) to clarify the relationship between fatty acid oxidation and glucose synthesis. In Expt 1, newborn pigs were either fasted from birth for 24 h or allowed to suck ad lib. for 3 d followed by a 24 h fast. In the presence of pyruvate, oxidation of octanoate (2 mM) was about 30-fold greater than oleate (1 mM) regardless of age, but glucose synthesis was not enhanced beyond that observed for pyruvate alone. Inclusion of carnitine (1 mM), glucagon (100 nM) or dibutryl CAMP (50 p~) in the incubation media did not stimulate either fatty acid oxidation (octanoate or oleate) or glucose synthesis. Extending the period of fasting to 48 h (Expt 2) failed to enhance the fatty acid oxidative capacity or glucose synthesis rate. Likewise, the redox potential of the gluconeogenic substrate (lactate v. pyruvate) did not influence glucose synthesis regardless of the oxidative capacity exhibited for fatty acids. These data indicate that fatty acid oxidative capacity is not the first limiting factor to full expression of gluconeogenesis in hepatocytes isolated from fasted newborn pigs.
1985, 60:659-665. J ANIM SCI http://jas.fass.org/content/60/3/659 services, is located on the Wor... more 1985, 60:659-665. J ANIM SCI http://jas.fass.org/content/60/3/659 services, is located on the World Wide Web at: