Metabolic Body Weight Basis Research Articles

Assessment of Sex, Age, and Metabolism Relationships to Serum Thyroid Concentrations in Retired Alaskan Husky Sled Dogs

Sled dogs are purpose-bred dogs selected for endurance work. Prior studies in racing dogs showed that serum thyroid parameters (total T4, free T4, and T3) are lower than the reference range in approximately 25% of dogs. Whether this is related to training, breeding, or body condition remains unclear. We hypothesized that retired sled dogs of normal body condition (9–13 years old) would have predominantly normal serum thyroid parameters and that serum thyroid status would be correlated to energy consumption based on metabolic body weight. Eighty-six sled dogs who were deemed healthy on physical exam, not on confounding medications, and without a prior diagnosis of hypothyroidism were included. All dogs' mean body condition scores were 5.1 ± 0.4 and body weight 24.5 ± 4.2 kg at fasting blood collection with stable dietary intake for 3 months before sampling. The total T4, free T4, and T3 serum concentrations were 23.4 ± 9.1 nmol/L, 9.53 ± 4.3 pmol/L, and 0.93 ± 0.39 nmol/L, respectively, with 38% lower than the reference range for total T4, 45% for free T4, and 37% for T3. All dogs were negative for thyroglobulin antibody, and TSH results were within normal ranges. Pearson's correlates based on kilocalories consumed on a metabolic body weight basis for total T4 (R = 0.14), free T4 (R = 0.01) and T3 (R = 0.23) showed poor correlation. No differences were observed between thyroid hormones and age, breed, or sex. Inactive, retired sled dogs can be misdiagnosed with hypothyroidism; therefore, our data suggests that misdiagnosis of hypothyroidism can occur and that the racing Alaskan sled dog has a unique reference range that should be considered when assessing serum thyroid status.

PSX-A-6 Late-Breaking: Conventional vs Heritage cattle supplement intake, weight-gains, and body condition scores on Chihuahuan desert pasture

Abstract Use of adapted beef cattle biotypes is gaining momentum as a novel management strategy for limiting the environmental footprint of ranching and adapting to climate change in the southwest. We compared supplement intake (SI), calf birthweights, cow weights, and body condition scores (BCS) of desert-adapted Brangus (BR; n = 15) vs. Raramuri Criollo (RC; n = 28) cows in four adjacent pastures (1098±85 ha) for three months (Mar 7 – Jun 9, 2020) using ANOVA for a RCBD (significance at P < 0.05). Cows had ad libitum access to 18% crude protein lick tubs in all pastures, which were weighed weekly to determine SI. Brangus cows had greater SI than RC, both overall (BR: 0.21±0.04 vs. RC: 0.08±0.03 kg×cow×d-1) and on a metabolic bodyweight basis (BR: 2.31±0.09 vs. RC: 0.95±0.09 g×kg0.75). All cows were bred to Brangus bulls and calf birth weights were not different between biotypes (BR: 31.5 ± 1.0; RC: 29.6±0.9 kg). Brangus cows weighed more at the beginning (535.0±14.8 kg) and end (582.2±14.5 kg) of the study compared to RC (beginning: 345.5±11.8 kg; end: 357.0±12.0 kg). Percent of bodyweight change was not different between biotypes (BR: 8.51±2.35; RC: 2.85±1.81 %). On a 1 to 5 scale, BCS of Brangus (4.06±0.09) was greater than RC (3.18 ± 0.07) at the onset of the study, but biotypes had similar BCS at the end of the trial (BR: 4.09 ± 0.09; RC: 3.89±0.08). Our preliminary results indicate that lighter RC cows were capable of gaining bodyweight and improving BCS with reduced SI, both overall and on a metabolic bodyweight basis. This finding may reflect lower nutrient requirements, better relative efficiencies and lesser grazing impacts on desert rangelands by RC cattle. Future studies will seek to replicate these breed-comparison trials over multiple years, research sites, and supply chains, with an emphasis on overall systems production efficiency and sustainability.

PSVI-10 Effects of lipid and starch supplementation on total water intake of Holstein bull-calves

Abstract Water intake of dairy calves is often overlooked by most nutrition models which can be associated with the misconception that dairy calves meet their water requirements with milk or milk replacer (MR) alone. The goals herein were to investigate the effect of two isoenergetic supplements fed in a MR diet on total water intake (TWI) and fresh water intake (FWI). Twenty-three Holstein bull-calves (94.67 ± 12.07 kg) were distributed in a completely randomized design and received one of three supplements for 68 days: control (CON; n = 7), carbohydrates (CHO; n = 8), and lipid (FAT; n = 8); on top of a MR-based diet. The CON was composed of ad libitum MR alone. The FAT was composed of a supplementation of menhaden fish oil on CON (3%); and CHO was composed of corn starch supplementation on CON. All animals were provided free access to mineral mix, 200 g daily dried brewer’s spent grains, and clean water. Data were analyzed with orthogonal contrasts for pre-specified treatment comparisons using R statistical software [R Core Team (2019)]. No significant differences were observed for MR intake, 3.13, 3.05, and 3.14 kg, final bodyweight, 208.75, 200.94, 202.64 kg, and average daily gain, 1.74, 1.60, 1.64 kg, for FAT, CHO, and CON, respectively. TWI in a metabolic bodyweight (MBW) basis was different (P < 0.05) amongst treatments; lower TWI intake was seen for FAT than CHO than CON (0.363 and 0.388 vs 0.423 L/kg0.75, respectively). TWI without MBW resulted in similar results (P < .05) with average TWI of 15.69, 16.08, and 18.00 L; FWI differences (P < .05) were seen alone 1.51, 2.59, and 3.77 L, as well as in MBW basis 0.033, 0.060, and 0.088 L/kg.75 for FAT, CHO, and CON. These data could potentially show that metabolic water production in early ruminant animals can significantly decrease water intake.

29 The effect of fleshing ability on cow and calf performance

Abstract Several factors influence the overall maintenance requirements of a mature beef cow including age, gain, lactation, pregnancy, and fleshing ability. However, limited research is available to distinguish what sets a hard-fleshing cow apart from an easy-fleshing cow. Cows that are hard-fleshing maintain a lower body condition score (BCS) throughout the year compared to easy-fleshing counterparts. The objectives of this experiment are to determine the differences in characteristics and production between cows classified as easy- vs. hard- fleshing. Characteristics of interest include feed intake, milk yield, milk composition, body weight changes, BCS changes, and other body composition measurements, as well as calf weaning weight. In this study, 24 spring-calving, mature Angus beef cows were classified as either hard-fleshing or easy-fleshing based on BCS and ultrasound measurements for back fat and rump fat. The intake study took place during the second trimester, cows were assigned to an easy- or hard-fleshing pen based on treatment where they remained for the entirety of the 45-day intake study. Each treatment was replicated three times in a completely randomized design. Milk data collection began one month after calving with monthly milkings from May-August. There were no differences (P = 0.9) in DMI, although hard-fleshing cows had greater DMI calculated on a metabolic body weight basis (P = 0.05). There was a trend (P = 0.12) for hard-fleshing cows to wean heavier calves, although there was no difference in mean milk yield (P = 0.44). Body condition score was positively correlated with protein and carbohydrate content of milk with easy-fleshing cows having greater contents of both (P = 0.02 and P < 0.01, respectively). Overall, an increase in BCS without an increase in DMI may be beneficial from a reproductive standpoint, though more research in this area is needed.

178 The Effect of Fleshing Ability on Cow and Calf Performance

Abstract Several factors influence the overall maintenance requirements of a mature beef cow including age, gain, lactation, pregnancy, and fleshing ability. However, limited research is available to distinguish what sets a hard-fleshing cow apart from an easy-fleshing cow. Cows that are hard-fleshing maintain a lower body condition score (BCS) throughout the year compared to easy-fleshing counterparts. The objectives of this experiment are to determine the differences in characteristics and production between cows classified as easy- vs. hard- fleshing. Characteristics of interest include feed intake, milk yield, milk composition, body weight changes, BCS changes, and other body composition measurements, as well as calf weaning weight. In this study, 24 spring-calving, mature Angus beef cows were classified as either hard-fleshing or easy-fleshing based on BCS and ultrasound measurements for back fat and rump fat. The intake study took place during the second trimester, cows were assigned to an easy- or hard-fleshing pen based on treatment where they remained for the entirety of the 45-day intake study. Each treatment was replicated three times in a completely randomized design. Milk data collection began one month after calving with monthly milkings from May—August. There were no differences (P = 0.9) in DMI, although hard-fleshing cows had greater DMI calculated on a metabolic body weight basis (P = 0.05). There was a trend (P = 0.12) for hard-fleshing cows to wean heavier calves, although there was no difference in mean milk yield (P = 0.44). Body condition score was positively correlated with protein and carbohydrate content of milk with easy-fleshing cows having greater contents of both (P = 0.02 and P < 0.01, respectively). Overall, an increase in BCS without an increase in DMI may be beneficial from a reproductive standpoint, though more research in this area is needed.

Pasture intake and grazing behaviour of growing European wild boar (Sus scrofaL.) and domestic pigs (Sus scrofa domesticus, Landrace×Large White) in a semi-extensive production system

SUMMARYThe objective of the present study was to determine the pasture intake of European wild boar and domestic pigs throughout their growth period (from 60 to 207 days of age). The proportion of time that each animal type spent grazing was also determined. Twelve 60-day-old pure-bred European wild boar (six castrated males and six females, average live-weight (±s.e.m.) 6·8 ± 0·37 kg) and 12 70-day-old domestic pigs (Large White × Landrace, six castrated males and six females, average live-weight [ ±s.e.m.] 24·1 ± 0·66 kg) were used in the study. Each day during the study, the animals grazed from 08·00 until 16·00 h, after which they hadad-libitumaccess to a supplemental diet for 1 h. Every 14 days throughout the study (a total of ten determinations), the pasture consumption was determined as the difference between the pasture dry matter (DM) availability pre- and post-grazing. The supplemental diet consumption was also determined. Three times during the study (age of animals 85, 140 and 198 days), the behaviour of each animal was observed over four consecutive days while grazing. When considered on a metabolic bodyweight basis, the pasture consumption of the European wild boar was greater than that in the domestic pigs. Approximately 0·20 of the total DM intake by the wild boar was pasture, whereas only 0·10 of the total DM intake by the domestic pigs was pasture. However, domestic pigs consumed a greater quantity of supplemental diet than the wild boar. The wild boar obtained 0·20 of their total daily dietary apparent energy intake from pasture, compared with 0·07 in the domestic pigs. Wild boar were more active during 8-h grazing periods spending 0·54 of their time grazing or moving around, compared with 0·32 of the time in domestic pigs.

Endogenous Nitric Oxide and Dopamine Regulate Feeding Behavior in Neonatal Layer-type Chickens

Abstract Evidence from animal studies suggests that endogenous nitric oxide and dopamine (DA) have a regulatory role in the rewarding system, but their interaction(s) have not been studied in avian species. In this study, 4 experiments were performed to determine the effects of central administration of L-arginine (nitric oxide precursor; 200 nmol), NG-nitro-L-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor; 100 nmol), amphetamine (an indirect DA agonist; 125 pmol) and DA (40 pmol) on feeding behavior in neonatal layer-type chickens (each experiment included 4 groups, n=12 birds in each group). Prior to the initiation of the treatments, birds were fasted for 3 hours (FD3). In experiment 1, chickens received intracerebroventricular (ICV) injection of saline, L-NAME (100 nmol), amphetamine (125 pmol), and combination of L-NAME + amphetamine. In experiment 2, chickens received the ICV injection of saline, L-arginine (200 nmol), amphetamine (125 pmol) and their combination. In experiment 3, chickens received ICV injection of saline, L-arginine (200 nmol), DA (40 pmol) and L-arginine + DA. In experiment 4, chickens received ICV injection of saline, L-NAME (100 nmol), DA (40 pmol) and L-NAME + DA. Thereafter, the cumulative food intake (on the basis of metabolic body weight) was recorded until 2-h post injection. The results showed that ICV injection of amphetamine or DA significantly decreased food intake (P<0.05). Also, co-administration of L-NAME + amphetamine attenuated the hypophagic effect of amphetamine (P<0.05), while combined administration of L-NAME and DA had no effect on DA-induced hypophagia. Additionally, the hypophagic effect of amphetamine was significantly amplified by L-arginine (P<0.05), but the combination of L-arginine and DA did not alter feeding behavior which was induced by DA. These results suggest an interaction between DAergic and nitrergic systems via a presynaptic mechanism on food intake regulation in layer-type chicken.

Equid milk production: evaluation of Martina Franca jennies and IHDH mares by Wood’s model application

The present work aims to evaluate milk production aptitude of two equid species: horse and donkey. The trial was conducted on the Italian Heavy Draught breed horse (IHDH) and on the Martina Franca breed donkey. Data were collected from 23 multiparous nursing IHDH mares aged from 6 to 10 years, with an average bodyweight (BW) (mean ± s.d.) of 822.3 ± 61.8 kg and from 28 multiparous nursing donkeys of Martina Franca breed aged from 7 to 12 years, with an average BW (mean ± s.d.) of 389.5 ± 21.2 kg. Milk yield was recorded on 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165 and 180 days in milk (DIM). At each milk yield evaluation day, a milk sample was collected and its composition was analysed. All data were normalised according metabolic weight (MBW) of animals, so to make comparable results of the two considered species. Wood’s lactation model was used to describe milk, fat, protein and lactose yield. Peak lactation was reached on DIM 69 in IHDH horse and on DIM 48 in Martina Franca donkey with a milk production of 10.693 kg/100 kg MBW (R2 = 0.9139) and 5.264 kg/100 kg MBW (R2 = 0.9428), respectively. Persistency index of milk lactation curve was higher in Martina Franca donkey then in IHDH mares (7.0338 vs 6.2672). IHDH mares showed higher fat and protein production. Lactose curves showed a similar trend in both the species although IHDH’s curve was characterised by higher values. Data reported in the present work underline that both breeds considered are characterised by good milk production aptitude. Moreover, high R2 values obtained applying Wood’s model to milk, fat, protein and lactose production, calculated on the metabolic bodyweight basis, are indices of goodness of model fit.

Methane Emission from Sheep Respiration and Sheepfolds During the Grazing Season in a Desert Grassland

Methane (CH4) emissions from ruminants should be accounted for the natural grazed rangeland ecosystems when devising greenhouse gas budget inventory, in particular, their contribution to global warming. In this study, CH4 emission from sheep respiration at different grazing intensities (light grazing, 0.75 sheep/ha, LG; moderate grazing, 1.50 sheep/ha, MG; and heavy grazing, 2.25 sheep/ha, HG) and in sheepfolds were evaluated in a desert grassland of Inner Mongolia. Results indicated that daily CH4 emission from sheep was not significantly different between treatments. When CH4 emission was expressed emission per 100g daily, there was a significant difference of LG vs HG and MG vs HG, with the values of 15.64g, 20.00g and 28.63g for LG, MG and HG, respectively, during the grazing season. There was no significant difference among CH4 fluxes in sheepfolds (mean 39.0 ug m-1 h-1). Considering CH4 emissions from the grazing ecosystem, net CH4 emissions from LG, MG and HG plots were -18.33, -1.91 and 21.19 g/ha/day, respectively. The digestibility of forage had a positive correlation with CH emission expressed on daily and metabolic body weight basis. It is concluded that MG will improve the balance between CH emission from grassland and grazing livestock in the desert grasslands of Inner Mongolia.

Impact of diets with different levels of leguminous roughages on nutrient intake, draught performance, blood biochemical and physiological parameters in dromedary camels

The experiment was conducted using nine dromedary camels of Bikaneri breed averaging 8–9 years age and 583–692kg body weight at National Research Centre on Camels, Bikaner, India. The effect of feeding different levels of leguminous roughages on nutrient intake, draught performance, blood biochemical and physiological parameters in dromedary camels was evaluated using completely randomized design over a period of 60 days. Among the leguminous roughages, groundnut haulms (Arachis hypogaea) and cluster bean straw (Cyamopsis tetragonoloba) were fed in one of three ratios, 75:25, 50:50 and 25:75 in treatments T1, T2 and T3, respectively and concentrate mixture as per requirement of the camels. The dry matter intake (DMI) on percent and metabolic body weight basis did not differ significantly among the treatments. However, digestible crude protein intake (DCPI) was significantly higher in T1 followed by T2 and T3. Likewise, total digestible nutrients intake (TDNI) was higher in T1 as compared to T2 and T3. The nutritive value was significantly higher in camels fed on T1 as compared to other treatments. The feeding of different levels of groundnut haulms and cluster bean straw influenced the speed of travel and power developed by the camels which was significantly better in T1 followed by T2 and T3. There was significant change in blood biochemical parameters with response to treatments and work. The treatment groups did not show any significant effect on lactate, triglycerides, phosphorus and calcium content of blood in camels before work. There was increase in lactate content in all the treatments manifold times after work. There was significant increase in glucose content when the camels were exposed to work which also differed significantly among the treatment groups. The increase in physiological responses was noted in all the treatments before and after work but the difference was statistically significant for pulse and respiration rates. It has been concluded from the results that feeding of groundnut haulms (Arachis hypogaea) and cluster bean straw (Cyamopsis tetragonoloba) in proportion of 75:25 had beneficial effect as compared to other treatment groups and is recommended for better performance of dromedary camels. However, the cluster bean straw in higher proportions can be used in the ration of dromedary camels with certain roughage improvement practices.

Exposure of growing and adult captive cheetahs (Acinonyx jubatus) to dietary isoflavones: twenty years later

Dietary isoflavones are associated with oestrogenic and anti-oestrogenic effects, and have been linked to infertility in cheetahs. This study aimed to determine the isoflavone content of commercially prepared diets consumed by captive cheetahs. Sixteen international zoological facilities provided diets, and the isoflavone content of each diet was determined by acid hydrolysis and HPLC quantification. Proximate nutritional composition was also determined. Over half the diets analysed contained detectable concentrations of isoflavones, whereby total isoflavone content ranged from 1.75-183 mg/kg dry matter. The zoo-specific diets were calculated to deliver a median isoflavone dose of 0.07 mg/kg body weight (BW) and a maximum of 1.95 mg/kg BW to captive cheetahs. On a metabolic body weight basis this equates to a maximum of 4.90-5.43 mg/kg(0.75) . Some diets prepared for hand-rearing neonatal cheetahs could expose neonates to doses of up to 4.24 mg/kg BW (or 4.24-6.33 mg/kg(0.75) for cubs under 3 months of age). Only one of six zoo-specific diets was found to deliver isoflavones in doses shown to possess biological activity in other species. Therefore, on average, dietary isoflavones were not found in commercially prepared diets consumed by captive cheetahs in concentrations predicted to cause physiological changes. However, a small proportion of these diets, including hand-rearing formulas, contained elevated isoflavones concentrations which may influence cheetah fertility, behaviour or other physiological parameters.

Nutritional Utilization in Malagueña Dairy Goats Differing in Genotypes for the Content of αS1-Casein in Milk

A study was carried out with 20 goats of the Malagueña breed, half with a high (HG) and half with a low (LG) genetic capability for αS1-casein (AS1-CN) synthesis, to determine whether the 2 different genotypes (that cause differences in goat milk composition) are related to differences in nutritional feed utilization. Among the 10 HG goats, 7 had BB and 3 had AB genotypes for AS1-CN, whereas there were 7 EF and 3 FF genotypes in the 10 LG goats. The goats were fed diets differing in crude protein content (13.6 vs. 17.7% dry matter for diets 1 and 2, respectively). For each genotype group, a balance trial was conducted with each of the 2 diets in a 2-period balanced changeover designed with half the animals consuming diet 1 and the other half diet 2, determining individual feed intake and the utilization of N and energy in the diets. Greater voluntary feed intake on a metabolic body weight basis among the HG goats was identified as the first possible cause of their milk production. The HG goats also had a greater level of feed utilization, on a metabolic body weight basis, for N and energy intake. Greater ratios of N balance/ digestible N, milk protein N/digestible N, milk energy/ digestible energy, and milk energy/ME were found for HG goats compared with LG. These effects appear to be dependent on the level of protein in the diet, indicating interactive effects. The greater N and energy utilization of HG versus LG goats may explain the differences in milk composition between the 2 genotype groups.

A Conjugated Linoleic Acid Supplement Containing trans-10, cis-12 Reduces Milk Fat Synthesis in Lactating Sheep

The efficacy of conjugated linoleic acid (CLA) supplements containing trans-10, cis-12 for reducing milk fat synthesis has been well documented in dairy cows, but studies with other ruminant species are less convincing, and there have been no investigations of this in sheep. Therefore, the current study was designed to determine whether trans-10, cis-12 CLA would inhibit milk fat synthesis in sheep. Twenty multiparous ewes in early lactation were paired and randomly allocated to 2 treatments: grass hay plus concentrate either unsupplemented (control) or supplemented with lipid-encapsulated CLA to provide 2.4 g/d of trans-10, cis-12 CLA. The CLA dose was based on published responses of dairy cows extrapolated to ewes on a metabolic body weight basis. The experimental design was a 2-period crossover with 10-d treatment periods separated by a 10-d interval. Compared with the control, CLA supplementation reduced milk fat content from 6.4 to 4.9% and reduced fat yield from 95 to 80 g/d. The CLA treatment also increased milk yield from 1,471 to 1,611 g/d and increased protein yield from 68 to 73 g/d. Milk protein content and DMI were unaffected by treatment. The reduction in milk fat yield was due to decreases in both de novo fatty acid synthesis and uptake of preformed fatty acids. Milk fat content of trans-10, cis-12 CLA was<0.01 and 0.12 g/100g of fatty acids for the control and CLA treatments, respectively. The transfer efficiency of trans-10, cis-12 CLA from the dietary supplement into milk fat was 3.8%. Results of the present study demonstrate that a CLA supplement containing trans-10, cis-12 CLA reduces milk fat synthesis in lactating sheep in a manner similar to dairy cows when fed at an equivalent dose (metabolic body weight basis). Furthermore, the nutrients spared by the reduction in milk fat coincided with an increase in milk and milk protein yield.

Do we really know vitamin and mineral requirements for infants and children?

Infants and young children require vitamins and minerals not only to replace losses through metabolic turnover, but also to increase body reserves as they grow. For infants up to six months of age it is generally assumed that breast milk provides adequate intakes, and average breast milk composition provides the basis of reference intakes for this age group, and the basis for infant formula. It is questionable to what extent the micronutrient content of breast milk reflects the infant's requirements as opposed to the mother's nutritional status. For obvious ethical reasons there have been very few (if any) experiments to determine the micronutrient requirements of infants and children, although studies of intakes in areas where deficiency is common provide an estimate of minimum requirements in some cases. Different national and international authorities have approached the problem of estimating reference intakes for infants and young children in four main ways: linear interpolation between adequate intakes estimated from breast milk composition and the experimentally-determined requirements of young adults; extrapolation forwards from breast milk composition and backwards from the requirements of young adults on the basis of metabolic body weight (body weight0.75), corrected by growth factors; extrapolation backwards from the requirements of young adults on the basis of the energy density of the diet; and by factorial calculation. Despite this, there is considerable concordance between the figures published by different authorities as a result of rounding off to avoid spurious precision.

Energy expenditure of splanchnic tissues and hindlimbs in growing lambs fed frozen rye-grass: effects of barley supplementation and changes between 2.5 and 7 months of age

In order to study the effects of barley supplementation (Exp. 1), six lambs of 40 kg of body weight were fed on either rye-grass or rye-grass supplemented with barley according to a tripli- cate Latin Square design at an estimated level of 1.5 and 2.0 fold the maintenance energy require- ments. In order to study the effects of age (Exp. 2), 3, 6 and 5 lambs aged 2.5, 4 and 7 months old respectively were used. They were fed with rye-grass only at estimated levels of 1.8, 1.7 and 1.5 fold the maintenance energy requirements. All animals were equipped with chronic blood catheters in the mesenteric artery, portal, hepatic and external iliac veins and with ultrasonic blood flow probes around the portal vein and the external iliac artery. In Experiment 1, portal blood flows increased by 11.5% with supplementation (P < 0.05) while iliac blood flow tended to increase by 15% (NS). Con- sequently, O2 consumption increased by 20% (P < 0.03), 35% (P < 0.08) and 19% (NS) in the portal drained viscera, liver and hindlimb, respectively, with barley supplementation. In Experiment 2, por- tal blood flow, expressed on a metabolic body weight basis, decreased by 17% from 2.5 to 4 months of age and did not change from 4 to 7 months (P < 0.004). Iliac blood flow did not increase significantly between 2.5 and 7 months of age due to large inter-individual variability. No significant effect of age was noted on portal drained viscera and liver energy expenditure expressed on a metabolic body weight basis, while the hindlimb energy expenditure tended to increase (NS). It was concluded that in supplementing ryegrass with barley, the increment in splanchnic and carcass energy expenditure ac- counted for 30 and 26% of the increment of ME intake in finishing lambs and experimental results on organ and tissue energy expenditure obtained in ruminant lambs below 7 months of age may be applied to growing and finishing lambs.

The nutritive value of citrus pulp ensiled with wheat straw and poultry litter for sheep

In experiment 1, 4 treatments were prepared consisting of a mixture of chopped wheat straw in different proportions, a fixed proportion of poultry litter and 0, 15, 30 and 45% citrus pulp on a dry matter basis. The mixtures were ensiled for 60 days at room temperature in polythene bags. Ensiling (time effect) resulted in an increase (P&lt;0.001) in titrable acidity level and a decrease in pH in the silage. In titrable acidity, there was an interaction effect (P&lt;0.001) between the levels of citrus pulp and the ensiling time, such that there was an increase (P&lt;0.001) in titrable acidity and a decrease (P&lt;0.001) in pH in the 4 treatments both before and after fermentation. However, compared with the premix, there was a large increase in titrable acidity in silage following fermentation. Ensiling resulted in complete elimination of all coliforms in spite of their presence in large numbers in the mixtures before ensiling. Although the total nitrogen content was not affected, ensiling resulted in an increase (P&lt;0.05) in the proportion of soluble nitrogen. The potential degradability of the silage dry matter ranged from 487 to 582 g/kg and increased (P&lt;0.05) with the level of citrus pulp. In experiment 2, the daily intake of dry matter, organic matter, digestible organic matter and the digestibility of organic matter increased significantly with levels of citrus pulp in the basal silage diet, but there was no difference (P&gt;0.05) in dry matter intake between diets containing 0, 76 and 167 g/kg citrus pulp when the intake was expressed on the basis of metabolic body weight. However, there was a decrease (P&lt;0.001) in intake of silage and diet dry matter, organic matter and digestible organic matter when the level of citrus pulp in the basal silage diet increased from 167 to 272 g/kg. Only animals on the basal silage diet containing 167 g/kg citrus pulp had a higher (P&lt;0.05) and positive nitrogen balance of 1.0 g/day. It is concluded that wheat straw and poultry litter can be ensiled successfully with citrus pulp to produce silage that is safe and of high fermentation quality. This silage has a medium to high feeding value in sheep, provided that the level of citrus pulp in the diet is in the range of 150–200 g/kg.

Effect of conjugated linoleic acid on energy metabolism in growing‐finishing pigs

SummaryThe effect of conjugated linoleic acid (CLA) on energy metabolism was studied in a respiration experiment with 20 growing pigs. From 70 kg liveweight onwards the animals received isoenergetic rations containing 0 or 3% CLA on the basis of metabolic bodyweight. Between 95 and 100 kg liveweight the gas exchange of each animal was measured over 48 h in a respiration chamber. This was preceded by a 5‐day quantitative determination of faeces and urine. The heat production and energy retention of the animals were determined by the carbon–nitrogen balance technique and the RQ method. Additionally several parameters of blood serum were determined. CLA had no effect on digestibility and metabolizability of energy, nor were gas exchange and heat production (HP) of the animals affected by the treatment. Average heat production across all measurements was 628 kJ/kg W0.75 in the control group and 636 kJ/kg W0.75 in the CLA group. No difference in fat deposition was observed (control 386, CLA group 379 kJ/kgW0.75). The N balance on the other hand was 2.2 g/day higher in the CLA‐supplemented animals. This caused retained protein energy, as a proportion of total energy retention, to increase from 24.2 to 25.8%. The ratio of retained protein energy to fat energy was 10% higher in the CLA‐treated animals than in the controls. Body mass increase over the trial as a whole was unaffected (control 27.6, CLA group 28.1 kg, equivalent to daily gains of 931 and 946 g, respectively). Blood serum lipoproteins exhibited few CLA‐induced changes. The greatest effects were observed in triacylglycerols, which were raised in the CLA animals compared with the controls. The ratio of cholesterol‐low‐density lipoprotein to cholesterol‐high‐density lipoprotein rose by 17% as a result of CLA treatment. Serum concentrations of albumin, creatinine, urea and glucose were unchanged. In conclusion, the study showed that supplementation with CLA under isoenergetic feeding conditions with a strongly positive energy balance has no marked effect on total metabolism, although a slightly enhanced deposition of protein was evident.

Energy intake and patterns of growth for male and female fallow deer of two genotypes, between 10 and 21 months of age

AbstractEuropean (no. = 36) and hybrid (¼ Mesopotamian, ¾ European; no. = 36) fallow deer (Dama dama) were evaluated for weight gain and energy intake from 10 to 21 months of age. Twelve each of bucks, does and castrated males (haviers) were tested for each genotype, in both concentrate-fed and pasture-based feeding systems. Based on weekly weighing hybrids (H) in each of the sex classes grew more rapidly (5 g/day across all groups) than the European (E) fallow deer (P &lt; 0·05). Haviers given concentrates grew significantly faster than pasture-fed haviers (P &lt; 0·01), whilst does grown on pasture grew significantly faster than those given concentrates (P &lt; 0·01). There was no significant difference in pattern of growth between bucks on pasture and those given concentrates (P &gt; 0·05). Does grew significantly less (P &lt; 0·01) than bucks and haviers in spring, summer and winter but environmental differences between years could not be accounted for in the analysis.Animals of all sexes and genotypes experienced rapid growth from 10 to 12 months of age (spring) and this was associated with energy intakes according to metabolic body weight (M0·75) these ranging between 0·8 and 1·1 MJ metabolizable energy (ME) per kg M0·75 per day. There were significantly (P &lt; 0·01) higher levels of energy consumed by H does and haviers in the summer, compared with their E counterparts but this was not associated with greater growth rates. However, H does had significantly higher (P &lt; 0·01) dressing proportions at slaughter than E does. The energy intake on a metabolic body weight basis for most groups declined to between 0·7 and 0·8 MJ ME per kg M0·75 per day from 12 to 21 months of age, except for the does, which declined even further to between 0·5 and 0·6 MJ ME per kg M0·75 per day from 17 months of age.There were no significant differences between E and H deer for energy intakes per M0·75, and H deer were slightly more energy efficient than their E counterparts in terms of growth rate in relation to annual gross energy intake. The food intake : weight gain ratio increased considerably for both genotypes after 14 months of age, indicating the desirability for slaughtering as soon as animals reach the target live weight. It was concluded that the crossbreeding system described is production efficient and produced offspring that reached slaughter weight sooner than E fallow deer and thereby produced carcasses with a greater wholesale value than their E counterparts of the same age.

Effect of nutrition on the balance of production of ovarian and pituitary hormones in ewes.

Nutrition-induced changes in liveweight can induce changes in ovarian function and ovulation rate. This study was designed to test the hypothesis that heavy ewes are able to maintain similar concentrations of follicle-stimulating hormone (FSH) to light ewes through a loss of responsiveness to ovarian negative feedback. This hypothesis leads to the prediction that administration of ovarian hormones on the basis of metabolic body weight would result in the same gonadotrophin (FSH) concentrations in-light and heavy ovariectomised ewes. We therefore examined the ovarian content of oestradiol and inhibin, and the FSH response to administration of these ovarian hormones in acutely ovariectomised heavy and light Merino ewes produced by differential feeding. At ovariectomy, follicular fluid was aspirated from the 6 largest follicles in each ewe and assayed for oestradiol and inhibin. Six days later, blood was sampled every 6 h for 2 days. Ewes were then given two subcutaneous progesterone implants and injected subcutaneously every 6 h for 5 days with oestradiol (37.4 ng kg-0.75) and charcoal-stripped bovine follicular fluid (0.04 ml kg-0.75). Blood was sampled before each injection and the plasma was assayed for FSH and inhibin. Oestradiol and its receptors were assayed in uterine tissue. Nutrition-induced increases in liveweight led to increases in the number of oestrogenic, potentially ovulatory ovarian follicles and the total ovarian content of oestradiol and inhibin. In the uterus, more oestradiol receptors and a higher oestradiol uptake were observed in light than in heavy ewes. After ovariectomy, FSH concentrations were inversely related to liveweight. However, when the ewes were treated with doses of ovarian hormones that were proportional to liveweight, the slope of the decline in FSH concentrations was independent of liveweight. We conclude that nutrition alters the balance between pituitary FSH secretion and gonadal feedback by changing the responsiveness to the inhibitory effects of oestradiol and inhibin.

Denervation increases clenbuterol sensitivity in muscle from young rats.

Clenbuterol has been shown to ameliorate denervation-induced atrophy and, therefore, clearly has therapeutic potential in the treatment of muscle wasting conditions in man. Previous studies have used dosages in rats which would be unacceptable in clinical practice, but the present results show that denervated muscle has a greater sensitivity to the drug than innervated or cardiac muscle. Fiber hypertrophy and an increase in protein and RNA content could be observed in denervated muscles but not in innervated muscles at a dose of 10 micrograms/kg body weight. When considered on a metabolic body weight basis, the effective dose in rats and the "safe" dose in man are surprisingly comparable. The observations imply that there is good reason to suppose that clenbuterol could be effective in ameliorating similar wasting conditions in man.