Use of monensin to restrict feed intake in sheep destined for live export

1986 ◽  
Vol 26 (6) ◽  
pp. 647
Author(s):  
RT Norris ◽  
CL McDonald ◽  
JB Rowe
Keyword(s):  
Feed Intake ◽  
Negative Relationship ◽  
Relationship Maintenance ◽  
Ad Libitum ◽  
Daily Intakes ◽  
Live Export

The accuracy with which monensin could control feed intake was studied in 200 3-4-year-old Merino wethers by measuring their intake of pelleted diets containing 5 levels of monensin: 0, 33, 66, 132 or 264 mg/kg of feed. The feed was offered ad libitum for 25 days except for the highest level of monensin where treatment was ended after 12 days.Mean daily intakes (g/sheep) of diets containing monensin at 0, 33, 66, 132 or 264 mg/kg feed were 1304, 959, 793, 403 and 137 respectively. Mean daily feed intake (Y, g) was negatively and linearly related to concentration of monensin (X, mg/kg feed) Y = 1244 - 6.57X (r2=0.98; P<0.05) Similarly there was a close negative relationship between the concentration of monensin (X, mg/kg feed) and daily liveweight change (Z, g/sheep) during the trial Z = 217 - 2.61X (r2=0.99; P< 0.01) From this relationship, maintenance of liveweight would have been achieved with a diet containing monensin at about 80 mg/kg feed. Signs of toxicity including deaths occurred in sheep receiving diets containing monensin at 66, 132 and 264 mg/kg feed. It was concluded that monensin could be used to restrict feed intake but further research is necessary to determine safe levels.

scholarly journals Effects of feeding level on efficiency of high- and low-residual feed intake beef steers

2020 ◽  
Vol 98 (10) ◽  
Author(s):  
Emily M Andreini ◽  
Sheyenne M Augenstein ◽  
Carrie S Fales ◽  
Roberto D Sainz ◽  
James W Oltjen
Keyword(s):  
Feed Intake ◽  
Energy Requirement ◽  
Average Daily Gain ◽  
Residual Feed Intake ◽  
Energy Requirements ◽  
Feed Restriction ◽  
Maintenance Energy ◽  
Ad Libitum ◽  
Ad Libitum Intake ◽  
Daily Intakes

Abstract Comparing heat production after ad libitum (ADLIB) and restricted (RESTRICT) feeding periods may offer insight into how residual feed intake (RFI) groups change their energy requirements based on previous feeding levels. In this study, the authors sought to explain the efficiency changes of high- and low-RFI steers after feed restriction. To determine RFI classification, 56 Angus-cross steers with initial body weight (BW) of 350 ± 28.7 kg were individually housed, offered ad libitum access to a total mixed ration, and daily intakes were recorded for 56 d. RFI was defined as the residual of the regression of dry matter intake on mid-test BW0.75 and average daily gain. High- and low-RFI groups were defined as &gt;0.5 SD above or below the mean of zero, respectively. Fourteen steers from each high and low groups (n = 28) were selected for the subsequent 56-d RESTRICT period. During the RESTRICT period, intake was restricted to 75% of previous ad libitum intake on a BW0.75 basis, and all other conditions remained constant. After the RESTRICT period, both RFI groups had decreased maintenance energy requirements. However, the low-RFI group decreased maintenance energy requirements by 32% on a BW0.75 basis, more (P &lt; 0.05) than the high-RFI group decreased maintenance requirements (18%). Thus, the low-RFI steers remained more efficient after a period of feed restriction. We conclude that feed restriction decreases maintenance energy requirement in both high- and low-RFI groups that are restricted to the same degree.

THE DEVELOPMENT OF FEED INTAKE PREDICTION EQUATIONS FOR LACTATING DAIRY COWS

1981 ◽  
Vol 61 (1) ◽  
pp. 151-157 ◽  
Author(s):  
D. H. YUNGBLUT ◽  
J. B. STONE ◽  
G. K. MACLEOD ◽  
D. G. GRIEVE ◽  
E. B. BURNSIDE
Keyword(s):  
Milk Production ◽  
Feed Intake ◽  
Dry Matter ◽  
Negative Relationship ◽  
Regression Equations ◽  
Prediction Equations ◽  
Data Set ◽  
Feed Composition ◽  
Independent Variables ◽  
Ad Libitum

Data collected during two long-term experiments were analyzed by stepwise multiple regression to develop feed intake prediction equations. In one experiment (Sire comparison trial (SCT)) cows were individually fed complete rations ad libitum while in the other (lifetime silage trial (LST)) roughage was fed ad libitum and grain according to production. Each experiment covered three lactations. Milk production and feed intake were recorded daily, milk composition biweekly (LST) or monthly (SCT) and weight and feed composition monthly. The data included 100 SCT and 79 LST records representing 47 and 34 different cows, respectively. Only data from lactations of at least 280 days were used. The SCT cows were older (30 vs. 24.6 mo at first calving. Dry matter (DM) intake of the SCT cows increased linearly between lactations 1 and 2 but changed very little between lactations 2 and 3. Dry matter intake by the LST cows increased linearly over the three lactations. Each data set was used to formulate two prediction equations. Regression equations using 11 independent variables gave R2 values of 0.84 for both data sets. Equations, using five selected independent variables (lactation number, milk production, milk fat percent, body weight, and acid detergent fibre (ADF) content of ration) gave R2 values of 0.78 (SCT) and 0.77 (LST). The SCT equation described a negative relationship between ADF content and intake, while the LST equation showed a positive relationship.

scholarly journals Lysine and Methionine Supplementation for Dairy Calves Is More Accurate through the Liquid than the Solid Diet

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 332
Author(s):  
Jackeline Thais Silva ◽  
Evangelina Miqueo ◽  
Thaís Manzoni Torrezan ◽  
Nathalia Brito Rocha ◽  
Giovana Simão Slanzon ◽  
...  
Keyword(s):  
Feed Intake ◽  
Dairy Calves ◽  
Body Measurements ◽  
Negative Effects ◽  
Intermediate Metabolism ◽  
Lower Body Weight ◽  
Solid Diet ◽  
Holstein Calves ◽  
Methionine Supplementation ◽  
Daily Intakes

This study aimed to evaluate the performance and metabolic changes in dairy calves supplemented with lysine and methionine in milk replacer (MR) or starter concentrate (SC). Male Holstein calves (n = 45) were blocked and distributed in Control without supplementation (1) and; Lysine and Methionine supplementation to achieve an intake of 17 and 5.3 g/d in the SC (2) and to achieve of 17 and 5.3 g/d in the MR (3). MR was fed (6 L/d) until the 8th week of life when weaning occurred. Calves were followed until the 10th week of age. Feed intake was measured daily. Weight and body measurements were registered weekly. Blood samples were collected biweekly to evaluate the intermediate metabolism. The AA supplementation resulted in lower body weight at weaning and week 10. Calves fed SC Lys:Met had lower SC intake and lower total feed intake at weaning when compared to control. Calves fed control had higher heart girth, hip-width, and plasma glucose concentration. The supplementation with Lys and Met did not benefit dairy calves’ performance nor metabolism in this study. Supplementation through the MR was more efficient than SC to result in adequate daily intakes of AA. Further studies are needed to understand the negative effects of AA on calf starter intake.

scholarly journals PSXI-6 Calculating energy efficiency use for Nellore bulls divergent in residual feed intake

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 393-394
Author(s):  
Camila D A Batalha ◽  
Fabiana L De Araújo ◽  
Renata H Branco ◽  
Luis O Tedeschi ◽  
Sarah F Bonilha
Keyword(s):  
Energy Efficiency ◽  
Feed Intake ◽  
Subcutaneous Fat ◽  
Residual Feed Intake ◽  
Efficiency Index ◽  
Least Square ◽  
Metabolic Energy ◽  
Energetic Efficiency ◽  
Base Line ◽  
Ad Libitum

Abstract Retained energy (RE) and energetic efficiency index were measured in Nellore bulls from divergent classes of residual feed intake (RFI). Thirty-four Nellore bulls (15 low RFI-LRFI and 19 high RFI-HRFI) were feedlot finished and slaughtered with 385 ± 40 kg of body weight (BW) and 520 ± 26.2 days of age. At the beginning of the experiment, five LRFI and three HRFI were slaughtered and used as base line. Individual dry matter intake was recorded daily; initial and final BW were recorded after 16 h of fasting. Eight bulls, four LRFI and four HRFI, were fed at maintenance, receiving 65 g of DM/kg0.75 BW, and 18 bulls (10 LRFI and eight HRFI) were fed ad libitum. Diet had 19:81 roughage:concentrate, 88% of DM and 15% of crude protein. Ultrasound measurements on the Longissimus muscle were performed at intervals of 28 days. When two ad libitum bulls reached 4 mm of subcutaneous fat thickness, one maintenance bull was randomly chosen and slaughtered on the same day. After slaughter, the centesimal composition of the empty body and carcass was measured. Data were analyzed using a random coefficients model, and RFI class was included as a fixed effect. Least-square means were used to compare the means, and significance was declared for P ≤ 0.05. The LRFI had greater protein retention than HRFI (248 vs. 142 g/d; P = 0.009), and same fat and energy retention (313 g/d and 4.12 Mcal/d, respectively). The energy efficiency indexes, heat production per metabolic energy intake (Mcal/Mcal) and gain-to-feed (kg/kg) ratio, did not differ between RFI classes. Though LRFI had the same energy efficiency index, they were leaner. These results indicated an association of RFI and maturity patterns. Further research is needed to estimate the net energy requirements of Nellore bulls classified according to RFI. Acknowledgments: FAPESP Processes 2017/06709-2, 2018/20080–2 and 2019/17714-2.

Insulin secretion, body composition and pig performance are altered by feeding pattern

2014 ◽  
Vol 54 (3) ◽  
pp. 319 ◽  
Author(s):  
Ronald E. Newman ◽  
Jeffery A. Downing ◽  
Peter C. Thomson ◽  
Cherie L. Collins ◽  
David J. Henman ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Feed Intake ◽  
Plasma Insulin ◽  
Feeding Strategy ◽  
Growing Pigs ◽  
Carcass Composition ◽  
Production Performance ◽  
Feed Conversion ◽  
Ad Libitum ◽  
Entire Male

Three studies investigated the effect of feeding strategy on production performance and endocrine status of growing pigs. For Experiment 1, 20 entire male pigs (70.0 ± 4.6 kg) were allocated randomly to individual pens in one of four climate-controlled rooms. Pigs were fed for 23 days either ad libitum or entrained to feed bi-phasically for two 90-min periods. For Experiment 2, 20 entire male pigs (41.2 ± 3.5 kg) were housed as per Experiment 1. Pigs were fed for 49 days either ad libitum or fed bi-phasically for two 60-min periods. For Experiment 3, 100 female pigs (66.1 ± 3.5 kg) were randomly allocated to individual pens within a commercial piggery and fed for 42 days either ad libitum or bi-phasically for two 60-min periods. Ear vein catheters were inserted into 10 pigs from each group and hourly blood samples were collected for 24 h in Experiments 1 and 2 and for 11 h in Experiment 3. Plasma insulin, non-esterified fatty acid and glucose concentrations were determined in Experiments 1 and 2, and glucose and insulin concentrations in Experiment 3. Feed intake and performance were recorded in all experiments and carcass composition was assessed by computed tomography for Experiment 2. There were no differences in final liveweight between the two treatment groups for all experiments. Pigs fed for two 90-min periods (Experiment 1) showed no difference in feed intake when compared with feeding ad libitum. Pigs in Experiment 2 fed for two 60-min intervals consumed 2.49 kg/pig.day compared with those fed ad libitum that consumed 2.68 kg/day (P = 0.057). In Experiment 3, pigs fed twice daily consumed 2.82 kg/pig.day compared with 2.91 kg/pig.day in ad libitum-fed pigs (P = 0.051). Bi-phasic fed pigs in Experiment 2 had improved (P < 0.05) feed conversion efficiency compared with pigs fed ad libitum. For all experiments, there was no difference in plasma glucose concentrations between the two treatments. In all three experiments, the circulating insulin concentrations for pigs fed ad libitum remained at a constant level throughout the sampling period. However, plasma insulin concentrations for the bi-phasic fed pigs significantly increased ~1 h after both feeding periods during all three experiments. Insulin secretion of pigs fed for two 90-min periods differed from that of pigs fed for two 60-min periods. Plasma insulin concentration increased five-fold following feeding for 60 min, compared with that in pigs fed for 90 min, which increased two-fold. Bi-phasic-fed pigs from Experiment 2 had reduced (P < 0.05) total carcass fat and significantly increased muscle when compared with pigs fed ad libitum. The data showed that feeding pigs at two succinct periods aligned insulin secretion to the time of feeding. Pigs fed for 60 min, unlike those fed for 90-min intervals, had reduced feed intake in comparison to those fed ad libitum. This may suggest that the duration of the feeding bout is important for this response and this may in turn influence both energy balance and the way energy is partitioned.

scholarly journals Short-term consequences of a sudden increase in feed allowance in broiler breeder hens

1993 ◽  
Vol 73 (1) ◽  
pp. 159-167 ◽  
Author(s):  
F. E. Robinson ◽  
M. W. Yu ◽  
M. E. Lupicki ◽  
R. T. Hardin
Keyword(s):  
Feed Intake ◽  
Egg Production ◽  
Liver Fat ◽  
Sudden Increase ◽  
Broiler Breeder ◽  
Breeder Hens ◽  
Preovulatory Follicles ◽  
Broiler Breeder Hens ◽  
Ad Libitum ◽  
Ad Libitum Feeding

The immediate effects of a sudden increase in feed allowance on selected morphological and reproductive traits were investigated in broiler breeder hens at 44 wk of age. Fifty Indian River hens were individually caged at 40 wk of age. Prior to 40 wk of age the birds had been feed restricted in accordance with the breeder's recommended feeding program. Five treatment groups (T1, T2, T3, T4 and T5) of 10 birds each were formed based on level of feeding and duration of exposure to such feeding. T1, T2 and T3 birds were feed restricted (128 g of daily feed bird−1) from 40 to 44, 40 to 45 and 40 to 46 wk of age, respectively. T4 and T5 birds were also feed restricted at the same level as the other groups to 44 wk of age and then were full fed from 44 to 45 and 44 to 46 wk of age, respectively. To facilitate study of follicular recruitment and yolk deposition, hens were fed 10 g of oil-soluble red and black dyes, daily, on alternate days, beginning at 42 wk of age. Birds were killed on day 0 (44 wk; T1), day 7 (45 wk; T2, T4), or day 14 (46 wk; T3, T5). Full-fed hens consumed approximately 100 g more feed per day than did feed-restricted hens, with marked increases in feed intake on the first day of full feeding. After 7 d of ad libitum feeding, significant increases were seen in body weight, liver weight, percent liver fat, plasma lipid concentration, ovary weight, and the incidence of a double hierarchy (simultaneous development) of large follicles. After 14 d of ad libitum feeding, significant increases were also observed in absolute fat-pad weight, individual weights of the four largest preovulatory follicles and number of large preovulatory follicles. The increased number of large follicles in the ovary was not associated with any change in egg production. It is apparent that the morphological disruptions associated with overfeeding broiler breeder hens can be identified within 7 d of full feeding, while any effects on egg production are not seen within the first 14 d of ad libitum feeding. Key words: Broiler breeder, feed intake, yolk deposition, ovarian morphology, egg production

Voluntary feed intake and apparent digestibility in vivo in ponies given ad libitum access to de-hydrated grass or hay harvested from the same grass crop

1998 ◽  
Vol 1998 ◽  
pp. 131-131
Author(s):  
J. J. Hyslop ◽  
A. Bayley ◽  
A. L. Tomlinson ◽  
D. Cuddeford
Keyword(s):  
Feed Intake ◽  
Chronic Obstructive ◽  
Apparent Digestibility ◽  
Obstructive Pulmonary Disease ◽  
Respiratory Problems ◽  
Voluntary Feed Intake ◽  
Grass Hay ◽  
Ad Libitum ◽  
The Uk

De-hydrated forages are often fed to equids in the UK in place of more traditional grass hay, particularly where individual animals are known to have a sensitivity to dusty, mouldy hay which may play a part inducing respiratory problems such as chronic obstructive pulmonary disease (COPD). One such alternative forage is short-chop de-hydrated grass. However, there is very little information available on voluntary feed intake (VFI), apparent digestibility and nutrient intake parameters when de-hydrated grass is offered to equids compared with traditional grass hay. This study examines the VFI and apparent digestibility in vivo of a short-chop de-hydrated grass compared with a traditional grass hay and determines their ability to meet the predicted energy and protein needs of mature ponies.Six mature Welsh-cross pony geldings with a mean liveweight (LW) of 281 kg (s.e.d. 0.89) were individually housed and offered ad libitum access to either short-chop de-hydrated grass (DHG) or traditional grass hay (HAY) plus 60 g/h/d minerals. The DHG and HAY were made from the same 2nd cut perennial ryegrass sward cut on the same day.

scholarly journals Post-weaning growth of cavies (Cavia porcellus) according to the inclusion level of ginger (Zingiber officinale) meal in the diet as a feed additive

2021 ◽  
Vol 14 (9) ◽  
pp. 3341-3352
Author(s):  
Loïc Arnold Mba Tene ◽  
Emile Miegoue ◽  
Marie Noëlle Bertine Noumbissi ◽  
Paulette Ntsafack ◽  
Camara Sawa ◽  
...  
Keyword(s):  
Feed Intake ◽  
Zingiber Officinale ◽  
Feed Additive ◽  
Cavia Porcellus ◽  
Feed Resources ◽  
Growth Performances ◽  
Ginger Powder ◽  
Inclusion Level ◽  
Ad Libitum ◽  
Growth Of Animals

The use of phytobiotics in feeding monogastric herbivores has several interests, including the stabilization of the caecal flora and especially the improvement of the growth of animals thanks to a better exploitation of feed resources. Thus a trial was conducted with an objective to evaluate the feed intake and post weaning growth performances of cavy according to the inclusion level of ginger meal. A total of 40 guinea pigs of 3 weeks of age were divided into 4 lots, and subjected to rations consisting of Trypsacum laxum served ad libitum, associated with the compound feed containing 0; 0.5; 0.75 and 1% ginger powder (T0, T1, T2 and T3). This study showed that the total intake of DM, MO and CB from forage was comparable between rations T0, T1 and T2 and significantly higher than those of ration T3. At weaning, average animal weights of all rations were comparable. However, at 8 weeks of age, the T0, T1 and T3 rations yielded comparable average weights, but significantly higher than those of the T2 animals, i.e., 272 g; 298.80 g; 285.25 g and 221.83 g, respectively. The T0, T1 and T3 diets recorded total gains that were comparable but significantly higher than those obtained with animals in Lot T2. Ginger powder can be included up to 0.75% in the diet as a feed additive for improved ingestion and 0.5% for post-weaning growth. L’usage des phytobiotiques dans l’alimentation des herbivores monogastriques présente plusieurs intérêts parmi lesquels la stabilisation de la flore caecale et surtout l’amélioration de la croissance des animaux grâce à une meilleure valorisation des ressources alimentaire. C’est ainsi que des essais ont été conduit avec pour objectif d’évaluer l’ingestion er la croissance post-sevrage des cobayes en fonction du niveau de la poudre de gingembre. Un total de 40 cobayes de 21 jours d’âge était reparti en 4 lots, et soumis à des rations constituées de Trypsacum laxum servi ad libitum, associé à l’aliment composé contenant 0 ; 0,5 ; 0,75 et 1% de poudre de gingembre (T0, T1, T2 et T3). Il ressort de cette étude que les ingestions totales de la MS, de la MO et de la CB du fourrage, ont été comparables entre les rations T0, T1 et T2 et significativement plus élevées que celle de la ration T3. Au sevrage, les poids moyens des animaux étaient comparables pour toutes les rations. Cependant à 8 semaines d’âge, les rations T0, T1 et T3 ont permis d’obtenir les poids moyens comparables, mais significativement plus élevés que ceux des animaux lot T2, soit respectivement 272 g ; 298,80 g ; 285,25 g et 221,83 g. Les rations T0, T1 et T3 ont permis d’enregistrer les gains totaux comparables, mais significativement élevés par rapport à ceux obtenus avec les animaux du lot T2. La poudre de gingembre peut être incluse jusqu’à 0,75% dans la ration comme additif alimentaire pour l'amélioration de l’ingestion et à 0,5% pour la croissance post-sevrage.

Feeding behaviour of Merino wethers under conditions similar to lot-feeding before live export

1990 ◽  
Vol 30 (3) ◽  
pp. 343 ◽  
Author(s):  
CL McDonald ◽  
RT Norris ◽  
EJ Speijers ◽  
H Ridings
Keyword(s):  
Western Australia ◽  
Feed Intake ◽  
Feeding Behaviour ◽  
Reliable Indicator ◽  
Central Location ◽  
Feeding Experiments ◽  
Linear Relationships ◽  
Diet Type ◽  
Live Export ◽  
As If

Sheep from different farms (lines) in Western Australia were mixed in 3 experiments and lot-fed for 6-7 days as if for export. A marking method to identify sheep which eat from troughs was tested and used to examine the effects of feeding treatments on the proportion of sheep which eat during lot-feeding. Paint soaked sponges attached to troughs were used to monitor whether sheep ate. Positive linear relationships between liveweight change and paint marking score (R = 0.93, 0.93 and 0.94, in the 3 experiments) suggested that the technique was a reliable indicator of feed intake. Feeding treatments imposed were period of fasting before lot feeding (experiments 2 and 3); and diet type (hay pellets, hay/pellet mix) and trough location in the feedlot (experiment 3). There were large differences between lines in the percentage of sheep not marked. Values � s.e. ranged from 1 � 1 to 79 � 3% for the 8 lines used in 3 experiments. In experiment 2, fasting for 48 h before lot-feeding resulted in more sheep (P<0.05) not marked (18 � 7 3%) than did fasting for <12 h (9 � 3%) and <24 h (8 � 2%). In experiment 3, fasting for 96 h compared with 48 h resulted in fewer sheep marked daily when fed a hay-pellet mixture (75 � 2 v. 93 � 1%; P<0.001). When fed only pellets in experiment 3, the percentages of marked sheep increased with time (days). Feeding pellets only compared with a hay-pellet mixture resulted in fewer sheep marked daily (60 � 2 v. 79 � 2%; P<0.001) and more sheep not marked (11 � 3 v. 3 � 2%; P<0.05). If troughs were located in the centre of yards instead of on the fenceline, it took 2 rather than 7 days for the daily percentage of animals marked on the pellets only diet to exceed 80%. The central location also resulted in a mean of 78 � 2% of sheep marked daily compared with 67 � 2% for fenceline troughs (P<0.001) and a mean intake higher (P<0.01) by 0.13 � 0.04 kg/wether.day. It was concluded that line of sheep, fasting, diet and trough location all had significant effects on feeding behaviour during lot feeding. Of these treatments, the greatest variation in feeding behaviour was associated with the line of sheep.

Influence of parasitism on plasma concentrations of growth hormone, somatomedin-C and somatomedin-binding proteins in calves

1988 ◽  
Vol 116 (2) ◽  
pp. 191-200 ◽  
Author(s):  
T. H. Elsasser ◽  
T. S. Rumsey ◽  
A. C. Hammond ◽  
R. Fayer
Keyword(s):  
Feed Intake ◽  
Binding Proteins ◽  
Binding Protein ◽  
Plasma Concentrations ◽  
Clinical Signs ◽  
Nitrogen Retention ◽  
Protein Patterns ◽  
Somatomedin C ◽  
Treatment Groups ◽  
Ad Libitum

ABSTRACT A parasitic disease model (sarcocystosis) was used to study the effects of infection and associated plane of nutrition on GH and somatomedin-C (SM-C) patterns in plasma, and SM-C binding protein patterns in plasma from 4-month-old male Holstein calves. Calves, matched by age and rate of growth before the experiment, were divided into three treatment groups (n = 7). In the first (control), animals were uninfected and food was available ad libitum; in the second, animals were infected with Sarcocystis cruzi and food was available ad libitum. The third group consisted of uninfected animals pair-fed to the level of feed intake of the infected animals. Blood samples were obtained at various times after infection for analysis of the secretory patterns of GH (day 27 after infection, samples every 10 min for 6 h), SM-C (days 27, 35 and 58 after infection) or binding protein (day 42 after infection). Samples were analysed for GH and SM-C by radioimmunoassay. Relative molecular weights of binding proteins were assessed by elution patterns from gel permeation columns. Clinical signs of infection were manifest abruptly on day 26 after infection. Voluntary feed intakes of infected calves as a per cent of control calves were 18, 46 and 78 on days 27, 35 and 58 after infection respectively. Plasma GH concentrations were lower in infected and pair-fed than in control calves (P < 0·05). Plasma SM-C concentrations were reduced in calves with diminished feed intakes and lower still in infected calves (P < 0·05). Plasma SM-C was positively correlated with nitrogen retention across treatment groups (r = 0·81). Two classes of binding proteins differing in molecular weight were identified. The relative amounts of each binding protein in plasma were reduced during low feed intake with some differences in the endogenous saturation affected by infection. These data suggest that altered growth and metabolism in parasitized calves may arise in part from both nutritional and infection-mediated effects on the regulation of GH, SM-C and SM-C binding proteins. J. Endocr. (1988) 116, 191–200

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