Intake Of Lambs Research Articles

Dried Poultry Manure as a Nitrogen Supplement for Young Cattle on Winter Grazing.

A feeding trial with young cattle, supported by measurements of digestibility and intake in lambs, was carried out to compare dried poultry manure (DPM) with cottonseed meal (CSM) or a urea maize mix (UM) as supplements to unimproved dry season grazing.Eighty Mashona steers, aged 9 months, initial live-weight 157 kg, were divided into eight groups, one of which was used as an initial slaughter group. The remainder were grazed by day and penned overnight (119 days). Whilst in the pens they received either no supplement (C) or DPM; CSM; UM; DPM + CSM; CSM + CSM; UM + CSM. The single supplements contained 150g crude protein and the double supplements 250 g crude protein per day. All animals were offered a mineral supplement and water was available during the day. At the end of the dry season half of the animals from each group were slaughtered and half retained to measure compensatory growth.Twelve lambs housed in crates each received one of the treatments (C, DPM, CSM, UM) with veld hay ad libitum (CP 2.5%) to measure digestibility and intake.

Comparative studies of sheep and goats: milk yield and composition and growth rate of lambs and kids

SummaryTwo trials were carried out to compare the milk yield, milk composition and the rate of growth of naturally or artificially reared kids and lambs of Damascus goats and Chios sheep.Milk yield until weaning was similar in sheep and goats, but goats produced significantly more milk after weaning. Sheep milk was higher in total solids, fat, protein, lactose, ash and calorific value.Lambs and kids grew similarly during thead libitummilk feeding period but lambs grew faster during the restricted milk feeding period. Solid feed intake of lambs until weaning was higher than that of kids and the results indicated that the rumen develops later in kids than in lambs. During the post-weaning period lambs consumed more feed, grew faster and utilized feed more efficiently than kids. Lambs were more sensitive to high copper supply than kids.

Improving the intake and nutritive value of wheat straw for beef cows

Two cow trials and two lamb metabolism trials were conducted to evaluate methods of improving wheat straw. In the first cow trial and lamb metabolism trial, the treatments of wheat straw were: (1) none (control); (2) 40 g kg −1 of sodium hydroxide (NaOH); (3) 60 g kg −1 of a liquid supplement (LS); (4) 37.5 g kg −1 of anhydrous ammonia (NH 3). In addition to wheat straw eaten ad libitum, all cows were given 7.5 kg of alfalfa-brome-grass hay three times weekly. In the second cow trial, the treatments of wheat straw were: (1) untreated straw plus 7.5 kg of alfalfa-bromegrass hay given three times weekly; (2) straw treated with NH 3 (37.5 g kg −1) plus 7.5 kg of alfalfa-bromegrass hay given three times weekly; (3) straw treated with NH 3; (4) straw treated with NH 3 plus whey (227 g/day). Similar diets were given in the second lamb metabolism trial. The NH 3 treatment of wheat straw given with alfalfa hay improved feed intake by an average of 13.8% ( P < 0.01) in the two trials and cow gains by 0.3 kg/day ( P < 0.05). In addition, NH 3-treated straw alone increased gain ( P < 0.05) by 0.1 kg when compared to untreated straw and hay in the second trial. However, LS- and NaOH-treated straw used in the first trial did not alter intake or gain. In the two lamb digestion trials, NH 3 treatment increased lamb intake ( P < 0.05) by an average of 29.2% and apparent dry matter digestibility (DMD; P < 0.05) by an average of 4.4%. No increase in apparent DMD was observed with NaOH or LS treatment of wheat straw. The NH 3 treatment increased the apparent digestibility of acid detergent fibre, neutral detergent fibre and hemicellulose.

Methods of improving the utilization of cereal straw by ruminants. II. Further studies on dried grass as a supplement for lambs

Sixteen growing castrated lambs (37.0 ± 3.31 kg) were used in two 5 × 5 and one 6 × 6 Latin squares to measure the intake and digestibility of: (1) urea—molasses-treated straw, or mixtures containing (2) 25; (3) 50; or (4) 75% dried grass; and (5) grass alone. The dry matter intake was 40, 50, 69, 84 and 90 g day −1 per kg of metabolic live weight ( P<0.001), and digestibility was 470, 489, 591, 671 and 735 g kg −1, respectively, for the above treatments. The dry matter intake of lambs offered diets 2, 3 and 4 as complete diets was 47, 56 and 66 g day −1 kg of metabolic live weight, and digestibility was 513, 621 and 673 g kg −1, respectively. When the feeds were offered separately, dry matter intake was 54, 63 and 78 g day −1 per kg of metabolic live weight and digestibility was 541, 582 and 662 g kg −1, respectively. Dry matter intake for mixed diets was higher ( P<0.01) than for feeds given separately.

Effects of treatment of barley straw with anhydrous ammonia and supplementation with heat-treated protein meals on feed intake and liveweight performance of growing lambs

Two feeding experiments were conducted in which lambs were given a basal diet of barley straw, supplemented with urea and minerals. The aim of the experiments was to increase lamb performance by (i) supplementation of the diet with protein meals that were largely undegraded in the rumen, (ii) treating the barley straw with anhydrous ammonia to increase its digestibility, or (iii) a combination of both. In Experiment 1, lambs were given the basal diet supplemented with 0, 60, 120, 180, 240, 300 or 360 g heat-treated protein-meal/kg straw. At the 300 g/kg level of supplementation, the protein pellet increased liveweight gain by 82 g/day, intake of barley straw by 110 g/day, and wool growth by 3.3 g/day, in comparison with unsupplemented lambs. In Experiment 2, untreated barley-straw or barley straw treated with anhydrous ammonia (4% w/w) was given to growing lambs. Each diet was supplemented (g/kg straw diet) with 100, 200 or 300 of two heat-treated protein-meals. Ammoniation of the barley straw increased dry matter (DM) digestibility in vitro from 49 to 57%, and hemicellulose content was reduced by 20%. Total N content of the straw was increased from 4.6 to 9.8 gN/kg DM by ammoniation, 65% of the increased N being potentially degradable in the rumen. As a result of ammoniation, digestible dry-matter intake of lambs was increased by 60 g DM/day and liveweight gain increased by 15 g/day. There was no significant difference between the two protein supplements with respect to either total feed intake or liveweight gain. Liveweight gain was significantly increased by both supplements (71, 106 and 125 g/day for each level of supplementation, respectively), but neither supplement had a significant effect on the intake of barley straw. Supplementation of a low-protein, low digestible diet of barley straw with a pelleted protein-meal considerably increased liveweight gain of growing lambs and maintained straw intake. By comparison, treatment of barley straw with anhydrous ammonia increased its digestibility, but had only a minor effect on lamb performance.

Short-term metabolic response in wethers to high dietary protein intake prior to fasting.

Twenty crossbred wether lambs (average body weight 38.9 kg) were examined for selected metabolic responses during fasting as affected by dietary protein level prior to fasting. Animals were fed diet analyzed at 10.4 and 20.3% crude protein (diets A and B, respectively) for 3 weeks and then fasted for 7 days. jugular blood samples were collected 4, 28, 52, 76, 100, 124 and 148 hr after the last feeding. Plasma glucose declined (P less than .05) between 4 and 52 hr, after which no further differences in plasma glucose occurred within or between treatment groups. Plasma urea N (PUN) was higher (P less than .05) in lambs fed diet B at 4, 28, and 52 hr postfeeding. In wethers fed diet A, PUN increased (P less than .05) from 28 to 76 hr postfeeding and then declined to prefasting levels. In wethers fed diet B, PUN did not begin to decrease until 76 hr postfeeding and then gradually declined (P less than .05) until the end of the fast. Plasma ammonia N increased (P less than .05) and plasma albumin decreased (P less than .05) during fasting in both treatment groups, but no differences were observed between the two groups in either parameter. The data support the existence of a "glucose-alanine" cycle in that alanine decreased (P less than .05) in both groups whereas glucose remained constant and PUN increased. Together, these factors suggest enhanced gluconeogenesis from amino acids. Increased branch-chain amino acid oxidation may be responsible for the decrease (P less than .05) in total branched-chain amino acids observed during fasting. The higher dietary protein intake of lambs fed diet B apparently afforded some nutritional advantage, since most of the changes observed occurred approximately 24 hr later in these lambs than in those fed the lower protein diet A before fasting.

Protein nutrition of growing lambs. 1. Responses in growth and rumen function to supplementation of a low-protein-cellulosic diet with either urea, casein or formaldehyde-treated casein.

1. The effects of supplementation of a cellulose-based diet with either urea, casein or formaldehydetreated (HCHO)-casein were studied in growing lambs. Responses were measured in terms of growth rate, food intake and food conversion ratio.2. In Expt 1 lambs were given free access to a basal diet containing (g/kg) oat-hulls (700) and solka floc (300) (containing 5 g nitrogen/kg dry matter (DM)) supplemented (g/kg basal diet) with either urea (25), untreated casein (75), HCHO-casein (75) or combinations of these. Food intake was increased on average by 27% above that on the basal diet by the addition of either urea, casein, HCHO-casein plus urea. Urea plus HCHO-casein when given as a combined supplement further increased food intake on average by 60% above that on the basal diet. Supplements of either urea, casein, HCHO-casein or casein or casein plus urea changed a mean live-weight loss of 40 g/d on the basal diet to a mean live-weight gain of 56 g/d. Urea plus HCHO-casein further increased lamb growth to 112 g/d.3. In Expt 2 lambs were given free access to the basal diet (plus 25 g urea/kg diet) used in Expt I. In this experiment the content of insoluble and soluble casein in the diets was varied by the addition of HCHO-casein and untreated casein of 0, 150; 50, 100; 100, 50 and 150, o g/kg basal diet respectively. Maximum lamb growth (141 g/d) was obtained with a supplement of 25 g urea plus 100 g HCHO-casein and 50 g casein/kg.4. The growth responses to these supplements suggest a requirement for soluble N by the rumen microorganisms to maximize rumen fermentation, and for maximum growth rate on this diet a further requirement for amino acids produced by protein which has escaped degradation in the rumen.5. Fermentation and the absorption of nutrients were examined in Expt 3 in lambs fitted with simple ‘T’-shaped cannula in the duodenum and ileum, and fed ad lib. one of the diets: a basal diet of oat hulls and solka floc, or the basal diet supplemented (g/kg) with either urea (25), urea plus casein (150), or urea (25) plus HCHO-casein (150). The rates of production of volatile fatty acids (VFA), methane and microbial cells were measured using isotope-dilution techniques. The apparent absorption of nutrients was determined by differences in the quantity of those nutrients in digesta at the duodenum and ileum.6. Supplements of urea, urea plus casein and urea plus HCHO-casein increased organic matter (OM) intake in lambs by 65% above that on the basal diet. OM digestibility was unchanged by the from of nitrogen supplementation. The rates of production of all fermentation end-products varied directly with voluntary food intake.7. Rumen methane production remained constant at 0.09 mol methane/MJ metabolizable energy (ME) intake on all diets, which represented an 11% loss of digestible energy (DE). Hindgut methane production was highest on the urea-supplemented diet.8. The rate of VFA production (mol/MJ ME intake) in the rumen was highest on the diet supplemented with urea in comparison with the basal, urea plus casein and urea plus HCHO-casein diets (which were not significantly different). The molar proportions of the individual VFA in rumen fluid were not significantly different between diets except for the branched chain and higher fatty acids which were highest in proportion with the urea plus casein diet.9. The loss of energy in the faeces, urine or as methane in expired air was not influenced by the form of N supplementation. DE and ME were greater on the supplemented diets, as a result of the increased OM intake of these diets.10. There was no effect of the form of N supplementation on OM digested in the rumen, small intestine or large intestine. Of an increase in OM intake, apparently 55% was digested in the rumen (of which 19% was incorporated into rumen micro-organisms) and 26% disappeared in the small intestines. The apparent digestibility of OM for all diets was 0.67.

The accuracy of tritiated water turnover rate as an estimate of milk intake in lambs

The accuracy of water turnover measurement as an estimate of milk intake was evaluated, with special reference to the validity of the assumptions underlying the technique. Even when milk was the only source of water for penned lambs, water turnover measurement significantly underestimated known milk intake. The underestimates were greater over longer measurement periods. It is suggested that these underestimates occurred because changes in body water pool size were not considered in the calculation of water turnover, since estimates were improved by the incorporation of a pool size correction. In a second pen trial, it was demonstrated that the inhalation of vapour from tritiated water excreted by other lambs was not a source of error in the estimation of water turnover. .In a field trial, the turnover technique was successfully employed to estimate milk intake in the first 3–4 weeks of life. A method for accommodating changes in pool size is presented, and it is suggested that the effects of pool size changes on the accuracy of the estimate of milk intake are too large to be ignored. In later weeks of the experiment, it was obvious that lambs were consuming water in forms other than milk, so that milk intake estimates were inaccurate. .It is concluded that in animals consuming only milk, measurement of tritiated water turnover provides an accurate estimate of milk intake, but only if changes in body water pool size are taken into account.

The effect of herbage allowance on herbage intake and performance of ewes and their twin lambs grazing perennial ryegrass

SUMMARYThe effect of herbage allowance on the intake and performance of Scottish Half bred ewes with twin lambs was investigated over the first 16 weeks of lactation. Herbage allowances were defined as g herbage D.M./kg live weight (LW)/day, and were maintained by provision of fresh areas of ungrazed sward each day.Herbage allowances in the range 25–120 g D.M./kg LW/day were offered on an area of perennial ryegrass (Lolium perenne cv. S. 23). Parturition was synchronized and ewes and lambs were turned out to pasture 1 day after lambing.Measurements were made of the herbage intake, live-weight change and milk yield of ewes, of lamb growth rates and of the herbage intake of lambs from 10 weeks of age.Herbage allowance had a significant linear effect on intakes of grass by ewes and lambs. The highest intakes by the ewes were achieved during the second week, and were in the range 23–43 g OM/kg LW/day. Intakes declined, as lactation proceeded, to 19–29 g OM/kg LW/day at week 12. Intakes of lambs were similar in weeks 10 and 12 and were in the range 17–24 g OM/kg LW/day. Allowance had a significant effect on live-weight change of the ewes after the first month and upon final body condition.There was no effect of allowance on milk yield until week 6. Mean milk yields were 2·3 kg/day at day 14, 1·0–1·5 kg/day at day 42 and 0·7–1·1 kg/day at day 84. There was a positive effect of allowance on growth rates of the lambs after the first month. Mean overall growth rates to 84 days of age were 175–243 g/day.

Acidosis in preruminant lambs: effect of sodium bicarbonate on nitrogen utilization and voluntary feed intake

Thirty-three male crossbred lambs, aged 2–5 days at the start of the experiment, were used in four experiments. Experiment 1. Low protein milk replacers (0.10 of total energy as protein) that differed in acid-base balance and contained casein (diet A), cows' milk proteins (diet B) or isolated soybean proteins (ISP; diet C) were each fed to three lambs. Lambs given diet C excreted more urinary ammonia, chloride and phosphorus, but less magnesium and sodium than lambs given diets A and B. Experiment 2. Three lambs were given diet C (49 mg sodium per MJ) in three successive 9–11 day periods. When sodium bicarbonate (114 mg sodium per MJ) was added in period 2, there was a reduction in urinary ammonia nitrogen excretion (from 0.23 to 0.10 of total urinary nitrogen), but no net change in nitrogen balance. Experiment 3. The supplement of sodium bicarbonate to diet C was increased to 228 mg sodium per MJ for three lambs. Urinary ammonia nitrogen excretion decreased to 0.03 of total urinary nitrogen, but nitrogen balance was again unchanged. Experiment 4. Nine lambs were given diet C with a supplement of sodium bicarbonate to provide an additional 282 mg sodium per MJ. Nine lambs were given the unsupplemented diet (49 mg sodium per MJ). The quantity of milk replacer offered was slowly increased on alternate days. Voluntary intake fell below the amount offered after 7 days in both groups. The voluntary intake of lambs given sodium bicarbonate was significantly higher than that of the unsupplemented lambs after 9 days.

The effect of temperature and method of feeding on the diestibility of two milk substitutes and on the performance of lambs

SUMMARYThe effects of temperature and method of feeding on the intake characteristics and digestibilities of two milk substitutes were examined.Forty Finnish Landrace x Dorset Horn lambs (20 males and 20 females) were fed one of two milk substitutes from 3 to 25 days of age when they were slaughtered and chemical composition of the empty body was measured.The two milk substitutes contained 30% fat in the dry matter as butter fat (diet B), or tallow and coconut oil (diet TC).The diets were offered at either 34°C (W) or 5 °C (C) and three methods of feeding were used. The diets were given: ad libitumcold (AL1), four feeds to appetite per day either warm or cold (AL2W and AL2C) and four feeds restricted to an intake of 62 g D.M./kg live weight0·5 either warm or cold (RW or RC).Digestibilities of the milk substitutes were not affected by the temperature at which they were offered or the feeding regime used. Diet B had an apparent dry-matter digestibility of 97·6% and diet TC 92·5%. The fat digestibility of diet TC was 13·6 units lower than diet B and this affected the digestibility of all the other dietary components.Lambs tended to consume more of diet B and grow faster.Lambs on treatment AL1 consumed 21% more milk substitute than those on treatment AL2.The composition of the body-weight gain was found to alter with rate of gain.The temperature at which the milk substitutes were offered had only a minor effect on the performance of the lambs. The type of milk substitute and feeding regime used had a greater influence on both lamb intake and growth.

FEED INTAKE AND NUTRIENT DIGESTIBILITY OF GROWING LAMBS SUPPLEMENTED INTRAGASTRICALLY WITH FULL-FAT RAPESEED (CV. TOWER)

Seventeen lambs were used to study the effects of ruminal and/or abomasal infusions of rapeseed on voluntary feed intake, nutrient digestibility and nitrogen retention. The basal diet (65% barley, 30% ground hay) contained 92% dry matter, 12% protein and 3.9 kcal/g of gross energy as fed. In experiment 1, full-fat rapeseed (FFRS, 25% protein, 50% fat) was either heated in boiling water or non-heated and infused into the abomasum of lambs as a 20% solids suspension to provide 25% of the daily energy requirement for maintenance. The intake, nutrient digestion and nitrogen retention of lambs were not affected by the heat treatment. In experiment 2, abomasal infusions of 0, 100, 200 and 400 ml of saline did not affect the "hunger drive" or daily feed intake of lambs. In experiment 3, FFRS (20% solids) was infused into the abomasum at levels of 12.5 and 25% of the energy requirements for maintenance with no infusion as control. Within 30 min post-infusion, voluntary energy intake decreased with increasing levels of FFRS infused (r = − 0.68, P &lt; 0.01), but the total of the energy consumed during this time period plus that infused was not different. Nutrient digestibility, nitrogen retention and average daily gains were not affected by the infusion level. In experiment 4, 15% of maintenance energy requirements were infused as FFRS into the rumen or abomasum. Voluntary energy intake at 30 min post-infusion was lower following infusions into the rumen or abomasum as compared to no infusion (P &lt; 0.01). Daily energy intake, weight gain and nutrient digestibility were not affected by the site of infusion. Nitrogen retention was lower when FFRS was infused into the rumen. In experiment 5, partially extracted rapeseed (31% protein, 15% fat) was infused into the abomasum to supply either 0.1 or 0.2 g of nitrogen per kg0.75 body weight and compared to non-infused controls. Voluntary intake at 30 min post-infusion was lower for lambs that received the infusions (P &lt; 0.02). Daily energy intake and nitrogen retention were not affected by the level of infusion. Nutrient digestibility increased gradually with each level of infusion (P &lt; 0.01). These experiments indicate that intra-abomasal supplementation with Tower FFRS does not improve the performance of growing lambs fed a pelleted diet containing about 12% crude protein. The FFRS protein had low solubility in rumen fluid, in vitro, and therefore may be only partially degraded in the rumen in vivo.

Plasma urea nitrogen as an indicator of protein quality. I. Factors affecting the concentration of urea in the blood of the preruminant lamb

Preruminant male crossbred lambs, aged between 2 days and 5 weeks, were given milk replacers of low (0.10 of total energy as protein) or medium (0.28) protein content. Plasma urea nitrogen (PUN) values were unaffected by: the time of blood sampling within 9 hr after feeding; the age of the lamb, between 3 and 33 days; the lamb's intake of the medium protein diet (range, 500–1180 kJ gross energy/day per kg0.73 storage of plasma samples at –15°C for 5 months before analysis; fasting of lambs for 4 days; feeding of lambs on a nitrogen-free diet for 7 days. PUN values were significantly increased by: an increase in the dietary protein concentration; a reduction in the lamb's intake of the low protein diet below 840 kJ gross energy/day per kg0.73 (negative nitrogen balance); an increase in the dry matter content of the medium protein diet from 0.10 to 0.25; the addition of urea to the low protein diet (peak values 4–6 hr after feeding). PUN values estimated on successive days reflected a change in the protein content of the diet within 3–4 days, regardless of whether the change in protein concentration was from low to medium, or medium to low. It is concluded that PUN values can be used to evaluate protein quality only when experimental conditions are strictly controlled. Blood samples taken without regard to the above factors may give misleading results.

The effects of quantity and distribution of milk substitute on the performance and carcass measurements of artificially reared lambs

SUMMARYTwenty-seven groups of Finnish Landrace × Dorset Horn lambs each of 2 castrated males and 2 females were offered daily quantities of 180, 248 or 343 g of milk substitute dry matter (DM) for 21, 29 or 40 days. Concentrate pellets were available ad libitum and from 22 days of age 150 g of hay per week was offered. When the mean live weight of a group reached 35 kg two castrates and one female from each group were slaughtered and the carcasses appraised.The growth rate and daily concentrate intake of lambs from 48 days of age until slaughter (reported -in this paper) were not affected by previous treatment, but lambs weaned at 40 days had a higher food conversion efficiency in this period (0·266 kg gain/kg feed DM) than those weaned at 21 days (0·244) or 29 days (0·232).Delaying weaning from 21 to 29 and 40 days reduced overall concentrate DM intake from birth to slaughter (from 88·15 to 81·09 and 73·39 kg) but increased growth rate (261, 276 and 288 g/day) and the conversion of total DM consumed to live weight (0·300, 0·311 and 0·350 kg/kg). Increasing the daily allowance of milk substitute from 180 to 248 and 343 g/day also reduced total concentrate intake (84·18, 80·74 and 77·71 kg). Growth rate and food conversion efficiency tended to increase and concentrate DM intake to decrease when the same total quantity of milk substitute was given over a longer period. Castrated males grew faster than females (290 v. 260 g/day).Weaning age generally had a greater effect than daily allowance of milk substitute on carcass measurements. Fat in the carcass tended to increase with increasing weaning age and significant interactions between daily allowance of milk substitute and weaning age were found for some carcass measurements.

Correlation of food intake in lambs with adipocyte glucose metabolism and NEFA release.

1. Experiments were conducted with lambs to determine the correlation between food intake, rate of glucose incorporation into CO(2) and lipids, and rate of lipid mobilization by their isolated omental adipocytes.2. During the interval between weaning and slaughter average daily dry matter (ADDM) intakes of the individual lambs were significantly correlated with average daily gains; however, the ratio of ADDM intake to body wt.((3/4)) was similar in all individuals.3. The average size of adipocytes for each lamb, as determined by lipid: protein ratios, was not significantly correlated with food intake.4. Oxidation of glucose to CO(2) and the total measured glucose incorporation by the adipocytes were significantly and negatively correlated with lamb ADDM intakes at low levels of glucose (0.1 mg/ml.), whereas rates of lipogenesis from glucose were similar for all intake levels.5. Insulin-induced increases in glucose utilization were positively and significantly correlated with ADDM intakes to the extent that insulin had over twice the effect on the adipocytes from high-intake lambs as it had on those from low-intake lambs. The minimum effective dose of insulin necessary to significantly increase glucose utilization by the adipocytes was also positively and significantly correlated with the ADDM intakes of the lambs.6. Basal NEFA release rates were higher for adipocytes from low-intake lambs. Epinephrine significantly increased NEFA release rates, independent of lamb intakes.7. A larger number of adipocytes in the high-intake lambs means that they would have a greater total potential to lower blood glucose, particularly when they are under the effects of normal circulating levels of insulin. The amount of glucose removed from the glucose pool could be the feed-back signal which results in a high long-term food intake.

The control of voluntary food intake in ruminants

SUMMARYAn experiment to test the effect on the voluntary food intake of lambs of giving diets containing 0, 20, 40 and 60% of either coarse or finely ground oat husks, in either a loose or pelleted form, is described and the results discussed. The results showed that voluntary intake was uniformly depressed with increased dilution of the diet with oat husks when the oat husks were coarse and the diet given loose. However, when the oat husks were finely ground and when the diet was pelleted the response to dilution was much modified and in the case of older, heavier lambs intake initially increased with dilution. It is concluded that ruminants may sometimes be able to respond to increased diet dilution so as to maintain their maximum digestible-energy intake but that the attempt is often thwarted to varying degrees according to the physical form of the food. An hypothesis is suggested for the pattern of response in food intake to be expected according to the type of food given.

Milk Levels of Selenium and Vitamin E Related to Nutritional Muscular Dystrophy in the Suckling Lamb

Se, as Na2SeO2, was added to ewes' rations containing raw and autoclaved kidney beans to compare bean-heating effect on utilization of Se in preventing nutritional muscular dystrophy (NMD) in suckling lambs. Ration effects on digestibility, milk production, milk composition and daily lamb intake of Se and vitamin E were examined. Observations were also made on distribution of 75Se in lamb tissues in relation to treatment effects. Supplemental Se and heat treatment of beans reduced the incidence of NMD. Autoclaving increased the apparent digestion of bean Se, as well as increasing milk production and daily milk yield of Se and vitamin E. Addition of Se appeared to reduce milk fat but no other treatment effects on major chemical components were noted. 75Se consumed in the ewes' milk was distributed in lamb tissue in approximately equal proportion due to treatments, with the possible exception of the pancreas.

A comparison of methods of estimating milk intake of lambs and milk yield of ewes at pasture

The milk intake of lambs sucking strong-wool Merino ewes at pasture was estimated by the lamb-suckling technique. This measure of milk production was compared with the estimate of the milk yield of the same ewes obtained after oxytocin injections. The ewes were divided subjectively into two classes, those that would stand for the lamb throughout the lamb-suckling test period and those that would not. During the first four weeks of lactation the ratios of the oxytocin estimate to the lamb suckling estimate were 99:100 (P&gt; 0.10) for the former class and 106 : 100 (P&lt;0.01) for the latter class. The corresponding ratios during the last six weeks were 104 : 100 (P&gt; 0.05) and 116 : 100 (P&lt;0.01). It was concluded that for the former class the two techniques are in good agreement.

Genetic factors affecting the milk intake of lambs

The actual amount of milk produced by a ewe is influenced both by her own potential to produce milk and by the potential of the lamb to obtain it. Two experiments were carried out to investigate the relative importance of these factors. In each experiment there were two genetically different groups of ewes, of which some reared their own single lambs and some reared single lambs from the other group fostered onto them. In both experiments, the effect of the genotype of the lamb was greater than that of the ewe. In the first experiment, during the period 6–24 days after parturition, ewes suckling strong-wool lambs produced 7.2 g/hr more milk than those suckling Peppin lambs, while the strong-wool ewes themselves produced only 4.6 g/hr more than the Peppin ewes. In the second experiment, during the period 0–28 days after parturition, ewes suckling Corriedale lambs produced 11.6 g/hr more milk than those suckling strong-wool Merino lambs, whereas the Corriedale ewes themselves produced only 4.4 g/hr more than the strong-wool Merino ewes. The lamb genotype effects were statistically significant. In a third experiment, in which the strong-wool and medium-wool Merinos were compared when suckling twins, the strong-wool exceeded the medium by 10.8 g/hr in milk production for the period 6-24 days after parturition. Some implications of the results are discussed.

Studies of the Dentition of Sheep: I.—Clinical Observations from Investigations into the Shedding of Permanent Incisor Teeth by Hill Sheep

SUMMARY Long-term field and laboratory studies have been carried out on the development and loss of the permanent dentition of Scottish Blackface sheep on 6 hill farms in Scotland. Clinical observations confirmed that husbandry practices and farm effect are of importance in that they influence the age at which the shedding of permanent incisors first occurs. Sheep exchanged between farms took on the characteristics of the host flock for the pattern of teeth shedding. The practice of wintering sheep on turnips in situ, or loose, was again implicated as accelerating the shedding of the teeth of such animals. It was not possible to clarify the often alleged relationship between occlusal position and the shedding of teeth. Very few sheep were found which could be described as markedly undershot or overshot in the lower jaw. On one farm breeding ewes lost teeth earlier, and more of them lost teeth, than did wethers on the same farm, but at 4½ years of age both groups were severely affected. A study of the effect of the vitamin D and phosphorus intake of lambs on their subsequent dental history was inconclusive. In all experiments where excessively heavy and early shedding of incisor teeth occurred the mature teeth were mostly long but intact and apparently healthy. The factor of severe crown wear is thus not a problem in the flocks investigated.