Distribution of nematode larvae of sheep in tropical pasture plants

The aim of this work was to study the dynamics of parasitic nematode larvae of sheep (third larval stage), in tropical forage species. The experiment was composed of two different dry matter yield for each plant species, Pensacola grass (Paspalum saurae) and Aruana grass (Panicum maximum). The animals in the experiment were 28 Suffolk lambs that were 6–8 months old. Lambs were left in a naturally contaminated pasture for 86 days. A randomized design was adopted, collection of pasture was made every 15 days, separated into upper and lower portions and made larval enumeration. Lambs were evaluated by faecal egg count (FEC) to monitoring worm infection. The number of parasite larvae in both forages was similar (p > 0.05). However, higher (p < 0.05) infestation by helminth larvae in forage with lower dry matter yield, was observed in the upper portion of both plants studied. Animals with lower forage yield, for both forages, presented superior averages (p < 0.05) of FEC compared to higher forage yield pasture. Lambs grazing on Pensacola grass, with lower dry matter yield, showed increasing FECs over time. Lambs maintained on the pasture with higher yield of dry matter (Aruana) showed decreasing FECs over time. Similar results were observed when each pasture type was analysed for larval contamination. Epidemiologic and management implications are discussed in this work.     

Effects of grazing willow fodder blocks upon methane production and blood composition in young sheep

A 79-day rotational grazing experiment was conducted over the summer and autumn of 2007 to compare effects of grazing willow (Salix spp.) fodder blocks, a combination of small trees (i.e., 1.0 m) and herbage, or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) control pasture on breath methane (CH₄) emissions, concentrations and solubility of CH₄ and sulphur hexafluoride (SF₆) tracer gas in blood, and haematology variables in young growing female sheep (i.e., hoggets). Measurements of gases in blood followed a double equilibration technique with two (n = 20) replicate per treatment. Ten ewe hoggets in each replicate were dosed on day 22 with intraruminal slow release SF₆ capsules, an inorganic tracer gas used to calculate CH₄ emissions. Breath samples were collected over 5-day periods in weeks 5 (period 1) and 11 (period 2). Total condensed tannin (CT) concentrations calculated in the diet selected by the willow fodder block sheep was 12 g CT kg/dry matter intake, with negligible amounts in control pasture hoggets. Compared to control pasture, grazing willow fodder blocks reduced CH₄ emission/kg metabolic body weight (BW^0.75) by 20% in period 1 (P<0.01), but not in period 2. Blood CH₄ concentrations (ng/mL blood) were similar for both groups on day 36, but higher (P<0.001) on day 76 for hoggets grazing willow fodder blocks, while a different trend was observed for SF₆ blood concentration being higher (P<0.01) on day 36 in hoggets grazing willow fodder blocks, but similar in both groups on day 76. Repeatability of blood CH₄ concentration was 75% in period versus 84% in period 2. Methane and SF₆ Ostwald solubility coefficients in blood were similar in both periods for sheep grazing willow fodder blocks and the control pasture. Hoggets grazing willow fodder blocks had lower BW gain (65 g/day), carcass weight (16.1 kg) and carcass fatness (9.2 mm) than hoggets grazing control pasture (102 g; 18.3 kg; 11 mm). Hoggets dosed with SF₆ capsules had lower (P<0.05) red blood cells, haemoglobin and haematocrit concentrations when grazing either willow fodder blocks or control pasture, while neutrophil (P=0.063), platelet (P=0.073) and monocyte (P=0.072), white blood cell and total lymphocyte counts (P<0.05) were higher for willow fodder block-fed hoggets than those fed the control pasture. Differences in the reduction in CH₄ emission between periods from grazing willow fodder blocks may be due to more willow leaf being eaten during the CH₄ measurement period in period 1 than in period 2.     

Effect of high tannin grain sorghum on gastrointestinal parasite fecal egg counts in goats

The objective of three experiments was to determine the influence of high condensed tannin (CT) grain sorghum on gastrointestinal parasite fecal egg counts (FEC). Sixteen naturally infected Boer crossbred mixed-sex goats were used. Animals that were supplemented with grain daily were removed from pasture and placed in individual pens and fed treatment diets for 21 or 14 days (Experiment 3). Goats were allowed ad libitum access to water and diets containing high or low CT cracked grain sorghum. On day 0 and every 7 days thereafter, PCV, FEC and FAMACHA^® eyelid color scores (EYE; Experiment 1 only) were recorded. For Experiment 1, percentage of animals dewormed, PCV and EYE were not influenced by treatment and averaged 13.6 ± 4.5% per treatment period, 23.4 ± 0.8% and 3.2 ± 0.12, respectively, for all animals. The FEC increased after day 0 for control but not high tannin grain sorghum fed goats (treatment by day interaction, P < 0.02). As expected, EYE and PCV were negatively related (r = −0.45; P < 0.0005). For Experiment 2, there was no influence of diet on PCV or FEC, but there was an effect of day on FEC (P < 0.002) in which all goats had higher FEC on day 0 (1956 ± 219 eggs/g) than any other sampling day. For Experiment 3, there was no effect of feeding high CT grain sorghum on FEC (2992 ± 591 eggs/g) or PCV (25.1 ± 0.5%). In these studies, high CT grain sorghum did not consistently influence FEC and did not impact PCV or number of animals requiring chemical anthelmintic treatment.     

Effect of willow supplementation upon plasma amino acid concentration in ewes grazing drought pastures of low nutritive value

Effects of supplementing willow stem cuttings to ewes grazing drought pastures upon plasma amino acid (AA) concentrations was studied on Massey University's Riverside Farm, near Masteron, on the East Coast of New Zealand. Ewes of similar age and weight (i.e., 59.0 ± 2.22 kg) were assigned to two groups of 7 each, either with (supplemented) or without (control) supplementation of willow, and experimental grazing was carried for 10 weeks from early February until mid April of 2005. Live weight (LW) was recorded fortnightly and body condition score (BCS) was monthly. Blood samples for quantification of plasma amino acids were collected at week 5 and 10. Both groups had a similar pre-grazing pasture mass (i.e., 2000 kg of dry matter/ha) and dead matter content (0.80) with the diet selected by the ewes containing a metabolisable energy (ME) of 8.3 MJ/kg DM, which is typical of drought conditions. The willow was readily eaten, with intake averaging 0.26 kg DM/ewe/d. Willow was of higher ME content than short drought pasture (i.e., 10.1 versus 8.4 MJ/kg DM) and contained condensed tannins at 40.8 ± 1.97 g/kg DM. Both groups of ewes lost live weight at about 50 g/d. Plasma concentration of 3-methyl histidine (88 versus 127 μmol/L) at week 5 and non-essential amino acids (1082 versus 1417 μmol/L) at week 5 and (1155 versus 1324 μmol/L) at week 10, were substantially lower (P<0.05) in willow supplemented versus control ewes, indicating that willow supplementation reduced catabolism of body proteins in ewes under drought feeding conditions.     

Effects of social learning on foraging behaviour and live weight gain in first-season grazing calves

When livestock are turned out to semi-natural grasslands, an effective onset of grazing is important both for animal productivity and for defoliation of the sward, which preserve the biodiversity of the vegetation. The aim of this study was to investigate whether foraging behaviour of naïve calves turned out to pasture was more intense, with a resulting diminished live weight loss, when experienced cattle accompanied them acting as social models. Twenty-six first-season grazing (FSG) dairy calves, allocated to groups with or without company of older, grazing-experienced steers, were turned out to semi-natural grasslands. Cattle behaviour was automatically recorded for 24 h during the first day on pasture and during 24 h after 1 month. Furthermore, the average live weight changes for the first day and for the first month on pasture were calculated. Calves turned out to pasture accompanied by grazing-experienced steers had similar grazing times (on average 42.7% of the day) to calves turned out to pasture in groups without older steers, but they had higher grazing activity during the first day on pasture (score 124 vs. 99, P = 0.005). Live weight changes were similar in calves kept with as in calves kept without company of grazing-experienced steers (?4.60 kg for the first day and ?0.30 kg day^?1 for the first month on pasture). In conclusion, the company of grazing-experienced conspecifics resulted in higher grazing activity in naïve calves, but their time spent grazing and live weight gains were unmodified. Hence, in this limited study we found no major positive effects on production of using grazing-experienced cattle as company to FSG calves on semi-natural grasslands.     

Effects of feeding system on carcass and non-carcass composition of Churra Tensina light lambs

Thirty-eight single male lambs (3.6 ± 0.08 kg live weight at birth) were used to study the influence of feeding system on carcass and non-carcass composition of Churra Tensina light lambs. Treatments: indoor (IND), lambs housed indoors consuming concentrate ad libitum until weaning at 53 days of age, and ewes grazing 8 h a day without their offspring and receiving a supplement of barley meal after grazing; grazing (GR), ewes and lambs grazed continuously without concentrate and lambs were unweaned. When lambs reached 22–24 kg live weight they were slaughtered. Carcass and non-carcass composition was recorded. GR lambs displayed higher carcass shrink (P < 0.05) and lower dressing percentage (P < 0.01) than concentrate-fed lambs. IND lambs had more body fat mainly due to the heavier kidney (P < 0.001) and subcutaneous (P < 0.001) fat depots. Total non-carcass weight was not affected by treatment (P > 0.05), but red organ (heart, lung and trachea, thymus, liver, spleen, kidney, diaphragm, pancreas, gall bladder, bladder, and testicles and penis), digestive tract (stomach, small intestine and large intestine) and head, skin, and feet (HSF) weights differed between treatments (P < 0.05). IND lambs had heavier red organs and HSF (P < 0.05) although this difference disappeared when expressed as a percentage of empty body weight. Small intestine weight in grazing lambs was heavier (P < 0.001) and, consequently, the total digestive tract differed similarly (P < 0.01). Treatment influenced the weights (P < 0.05) of all joints except leg (P > 0.05), showing heavier joints for IND carcasses. The feeding system had a greater effect on subcutaneous fat (P < 0.001) than on intermuscular fat (P < 0.05) in most of the standardized joints. IND carcasses produced a greater proportion of muscle/bone in all joints, except neck, whereas GR produced a greater proportion of muscle/total fat due to the lower amount of fat recorded in this treatment. The percentage of fatty acids was not affected by treatment (P > 0.05) although the percentage of C18:3 was greater and the ratio of C18:2/C18:3 was lower in grazing-fed lambs. The absence of any effect of treatment on the fatty acid percentages may be influenced by the short raising period and by the similar amount of intramuscular fat in both treatments. It is concluded that light lambs reared under grazing conditions can produce carcasses of acceptable quality, due to the lower percentage of subcutaneous fat, but with a similar intramuscular fat content.     

Partial replacement of barley grain for corn grain: Associative effects on lambs’ growth performance

Our objective was to study the positive effects of partial replacement of barley grain for corn in high concentrate diets on growth performance of growing lambs, and to determine the minimum amount of corn needed to produce such effects. Thirty-three male Awassi lambs weaned at 60 days of age were divided into three groups of 11 according to their live weight and offered three isonitrogenous diets. The control diet (B) contained 81 and 14% barley grain and wheat straw, respectively (DM basis). Corn grain replaced barley grain at 10 and 20% of dietary DM for low (LC) and high (HC) corn diets, respectively. Barley had a higher (P < 0.05) rate of digestion (11.5%/h) compared with corn (8.3%/h). The in vitro 30-h digestion extent was also higher (P < 0.05) for barley. The digestion rate for the B diet was higher (P < 0.05) compared with the HC diet, whereas the value for the LC diet was intermediate. Lambs fed LC and HC diets consumed more (P > 0.05) DM (average = 855 g/day) compared with lambs fed B diet (757 g/day). DM and CP digestibilities were similar among diets and averaged 67.0 and 64.2%, respectively. Final BW, BW change and average daily gain (ADG) for lambs fed HC were higher (P < 0.05) compared with B and LC. Moreover, lambs that consumed LC tended (P = 0.12) to grow faster than lambs fed B. Feed to gain ratio was lower (P < 0.05) for lambs fed HC (4.6) compared with B and LC (5.2). In summary, positive associative effects of partial replacement of barley with corn in high concentrate diets for fattening sheep were detected. However, a minimum of 20% replacement of dietary DM from barley with corn was needed to positively improve both performance and feed efficiency.     

Responses of hair and wool sheep to a single fixed dose of infective larvae of Haemonchus contortus

Body weights, fecal egg counts (FEC), and packed cell volumes (PCV) of hair sheep and wool sheep crossbred lambs were compared over 8 weeks following administration of a single dose of approximately 10,000 third-stage larvae of Haemonchus contortus. Hair sheep lambs (n=17) were reciprocal crosses between mainland USA populations of Barbados Blackbelly (BB) and Virgin Islands White (VIW) sheep. Wool sheep lambs (n=64) were from a crossbred composite of 50% Dorset, 25% Rambouillet, and 25% Finnish Landrace breeding. Lambs of both breed types continued to grow during the period of infection. Mean weights were higher for wool lambs (39.7±0.8 kg) than for hair lambs (28.2±1.5 kg). FEC increased to week 5 in both breed groups and remained elevated in wool lambs through week 7 but declined sharply in hair lambs after week 5. Mean FEC for weeks 4 through 8 were 4011±361 eggs per gram of feces (epg) in wool lambs, and 1135±196 epg in hair lambs. PCV declined through week 7 in wool lambs but stabilized and then increased after week 4 in hair lambs. Mean PCV in weeks 4 through 8 were 22.4±0.3% in wool lambs and 24.3±0.5% in hair lambs. These results suggest that Caribbean hair breeds may be able to contribute significantly to development of parasite-resistant sheep populations.     

Growth performance and carcass traits of forage-fed hair sheep wethers

The objective of the present study was to compare live animal performance and carcass characteristics of 3/4 or 7/8 Dorper (DO; n = 30), purebred Katahdin (KA; n = 20), purebred St. Croix (SC; n = 17) and purebred Suffolk (SU; n = 10) lambs born in the spring and fall of 2001. After weaning, lambs were supplemented with up to 680 g of a corn-soybean meal supplement while grazing bermudagrass pastures overseeded with ryegrass. Lambs were slaughtered at approximately 210 d of age. From birth to weaning, DO lambs gained faster (P < 0.001) than KA or SC lambs, whereas KA lambs had higher (P < 0.001) ADG than SC lambs. Additionally, DO and SU wethers had greater (P < 0.02) ADG from weaning to slaughter than SC or KA wethers. Suffolk lambs were heavier (P < 0.001) at slaughter and produced heavier (P < 0.001) carcasses than lambs from hair-sheep breeds. Carcasses of KA lambs were fatter (actual fat thickness; P < 0.02) resulting in higher yield grades (P < 0.03) than carcasses of DO, SC, or SU lambs. Carcasses of DO and SU had larger (P < 0.001) longissimus muscle (LM) areas than those of KA or SC carcasses, whereas kidney fat weight and percentage were greater (P < 0.001) in carcasses from KA and SC than DO and SU lambs. Lean maturity was similar (P = 0.32) among breed-types. However, skeletal maturity was greater (P < 0.001) in SU than hair-sheep carcasses. Flank-streaking scores were similar (P = 0.19) among the breed-types, but conformation scores were higher (P < 0.001) for DO and SU carcasses and resulted in higher (P < 0.001) quality grades than SC carcasses. The LM of SU lambs was lighter (higher L^* values; P < 0.05) than that of KA and SC lambs, whereas the LM from DO lambs was redder (higher a^* values; P < 0.001) than SC and SU and more (P < 0.001) yellow than that of the other breed-types. Chops from SU lambs were tougher (higher shear force values; P < 0.007) than chops from the hair-sheep breeds. Results of this study indicate that ADG, carcass muscularity and meat quality were similar between DO and SU lambs, and, although fatter, carcass muscularity of KA was similar to that of DO lambs.     

Effects on ewe reproduction of grazing willow fodder blocks during drought

A grazing experiment was conducted in the summer/autumn of 2003 to determine the effect of grazing on willow fodder blocks at 6000 stems/ha during mating, relative to control ewes grazed on drought pasture, upon ewe production and reproduction. The fodder blocks contained a mixture of herbage and small trees. Grazing occurred over 10 weeks, from 19 February including three cycles of mating, with four groups of 100 ewes, comprising short drought pasture typical of drought pasture, long drought pasture typical of the pasture growing in the willow fodder blocks, short drought pasture with restricted access to willow fodder blocks (restricted access) and full access to willow fodder blocks (fenced on the willow fodder blocks all the time; full access). After mating, the four groups were joined and managed as one group until weaning in late November 2003. Ewe live weight (LW) and body condition score (BCS) change and reproductive rate at foetal ultra-sound scanning, lambing, docking and weaning were measured. Ewe wool production and staple length were measured at weaning. Short drought pasture had a pre-grazing mass of 1639 kg dry matter (DM)/ha with a dead matter content of 60%; typical of drought conditions. Herbage in the willow fodder blocks was similar to both control drought pastures (short and long) in nutritive value, with an organic matter digestibility (OMD) of 0.50. Tree yields were low in the fodder blocks, but they had higher concentrations of all secondary compounds, including 30 g condensed tannin (CT)/kg DM and OMD was higher, at 0.72. CT concentration was higher in the fodder block herbage than in short and long control drought pasture (5.0 g/kg versus 2.5 g/kg DM). Substantial LW loss occurred in the short control group (101 g/day), and reproductive rate was low, as would occur in severe drought conditions. Full access to fodder blocks lowered LW loss to 40 g/day and increased reproductive rate by approximately 20% units, with more ewes giving birth to twin lambs. Restricted access ewes had a low reproductive rate, similar to the short control group. Reproductive rate in full access treatment was slightly higher than in the long control group, despite similar calculated DM intakes in both groups. Calculated crude protein and CT intakes were higher for full access ewes than for any other groups, due to contributions from both the herbage and the trees; this may have increased the flow of undegradable dietary protein (UDP) to the small intestine and so have contributed to the increased fecundity of this group. Full access to willow fodder blocks proved beneficial in increasing ewe reproductive rate. However, both pasture and trees need to be managed as a tree/pasture system in order to produce herbage of higher nutritive value and more efficiently utilise willow fodder blocks as a supplementary feed.     

The effect of heather supplementation on gastrointestinal nematode infections and performance in Cashmere and local Celtiberic goats on pasture

A study was performed on 48 adult dry goats (16 local Celtiberic and 32 Cashmere does) at pasture and naturally infected with gastrointestinal nematodes to investigate the effects of heather supplementation on faecal egg count(s) (FEC) and live weight changes. The experiment was carried out in a mountain area in the north-west of Spain from June to November in 2003. Two plots of 10,550 and 9,050 m² with perennial ryegrass/white clover (Lolium perenne/Trifolium repens) pastures were established and a total of 24 goats (8 local Celtiberic does and 16 Cashmere does) were randomly allocated to each plot. The trial consisted of comparing live weight changes and FECs in goats fed heather supplement (treated group) or not (control group). A supplement of freshly cut heather was offered ad libitum to the treated group every 3 days in the morning. Cashmere does showed a significantly (P < 0.001) lower live weight decrease than the Celtiberic goats. The goats supplemented with heather showed a lower FEC than compared controls and this effect was significant (P < 0.05) in August and in the following controls (September, October and November). Two goats died before November in the control group. In conclusion, it seems that the availability of heather reduces the FEC in goats grazing ryegrass/white clover pastures and tends to improve their live weights.     

Milk fatty acid composition of dairy cows grazing at two pasture allowances and supplemented with different levels and sources of concentrate

Milk fatty acid (FA) composition of dairy cows from two grazing studies was examined. In the first study, effects of concentrate supplementation and pasture allowance were evaluated using 20 multiparous Holstein cows in five 4 × 4 Latin squares. The four treatments resulted from the combination of two pasture allowances (i.e., low, 25 versus high, 40 kg dry matter/cow/day) and two concentrate supplementation levels (i.e., 0 versus 1 kg concentrate/4 kg milk). No interactions occurred between concentrate supplementation and pasture allowance for milk FA composition. Concentrate supplementation increased short-chain FA content, and reduced the content of long-chain FA, trans11 C18:1, and cis9, trans11 conjugated linoleic acid (CLA) (1.36 versus 1.18 g/100 g). Concentrate supplementation increased saturated FA (58.6 versus 54.0 g/100 g) and reduced unsaturated FA content (39.9 versus 43.8 g/100 g). Grazing at high pasture allowance increased short-, medium-, and long-chain FA content, without affecting cis9, trans11 CLA content. Saturated FA content was higher (57.1 versus 55.6 g/100 g), and unsaturated FA content was lower (41.3 versus 42.5 g/100 g), when cows grazed at high pasture allowance. Concentrate supplementation reduced unsaturated FA and cis9, trans11 CLA in milk of dairy cows grazing at two pasture allowances. In the second study, two experiments evaluated effects of different energy supplements in grazing dairy cows. In Experiment 1, 25 multiparous Holstein cows were assigned to a cracked corn (CC) or a steam flaked corn (SFC) supplement containing 667 g/kg of corn grain plus a pelleted protein/mineral supplement. In Experiment 2, 22 multiparous Holstein cows were assigned to a ground corn grain (GC) or a non-forage fiber (NFF) supplement. The GC supplement contained 850 g/kg of corn grain, and the NFF supplement contained 440 g/kg of non-forage fiber sources (i.e., beet pulp, soyhulls, wheat middlings) that partially replaced corn grain. Milk FA composition was not affected by corn processing or carbohydrate source. The content of short-, medium-, long-chain FA, and cis9, trans11 CLA (2.5 g/100 g in Experiment 1; 2.1 g/100 g in Experiment 2) was similar between supplements in both experiments. The type of supplement did not affect the content of saturated (62.6 g/100 g in Experiment 1; 65.4 g/100 g in Experiment 2) and unsaturated FA (37.5 g/100 g in Experiment 1; 34.6 g/100 g in Experiment 2). Supplementation with supplements differing in the rate and extent of ruminal carbohydrate digestion did not affect the milk FA composition of grazing dairy cows.     

Effects of lambing season,sex and birth type on growth performance in Norduz lambs

The aim of this study was to evaluate effects of two production systems (spring and winter), sex and birth type on growth performance in Norduz lambs. Data were collected using 103 and 140 lambs born during the winter and spring, respectively. Lambs born in the winter were heavier (P < 0.01) than those born in the spring at birth, 90 and 180 days of age by 0.5, 1.6 and 1.7 kg, respectively. Ram lambs were heavier (P < 0.01) than ewe lambs at birth, 90 and 180 days of age by 0.5, 1.0 and 2.3 kg, respectively, while lambs born as singles were heavier (P < 0.01) than lambs born as twins at birth, 90 and 180 days of age by 0.9, 1.6 and 2.3 kg, respectively. Lambs born in the winter recorded a higher (P < 0.01) pre-weaning ADG (15 g/day) than spring-born lambs, while ram lambs recorded a higher (P < 0.01) pre-weaning ADG (11 g/day) than ewe lambs. The effect of birth type was not significant on pre-weaning ADG. The influence of lambing season and sex were also not significant on post-weaning ADG. Lambs born as singles recorded a higher (P < 0.01) post-weaning ADG (16 g/day) than lambs born as twins. Results suggest the winter season to give rise to heavier lambs at weaning and post-weaning and suggest lambs born in different seasons to have distinctly different growth patterns. The data also confirm that the influence of sex and type of birth on growth to be very important and to be take into account sheep production.     

Attempts to vaccinate ewes and their lambs against natural infection with Haemonchus contortus in a tropical environment

A vaccine containing integral membrane glycoproteins from the intestine of Haemonchus contortus was evaluated in three groups of grazing sheep each containing 13 ewes and their 16 lambs naturally infected with gastrointestinal nematodes. Two groups were vaccinated with either 5 or 50 μg of the antigen per immunisation, while the third, the control group, received adjuvant alone. The sheep were immunised six times at 3 week intervals, partly because the vaccine antigens are hidden and thus no immunological boost would be delivered by subsequent infection and partly because the level of Haemonchus spp. challenge was expected to be high. The vaccinated ewes, first immunised approximately 1 month before lambing, showed a circulating antibody response but no signs of reduced anaemia or Haemonchus spp. egg counts, compared with control ewes. Several ewes with severe haemonchosis in all three groups had to be given precautionary treatment with anthelmintic drugs. In contrast, vaccinating their lambs with either 5 or 50 μg of the antigen per immunisation resulted in 10 fold higher antibody titres. In the case of the lower antigen dose this was associated with significantly less anaemia, 72% reduction in the overall number of Haemonchus spp. eggs produced and significantly fewer worms compared with control lambs. It is hypothesised that the heavily pregnant or lactating ewes did not have sufficient physiological reserves to mount a protective response following vaccination in the tropical weather and high challenge conditions that prevailed. Nevertheless, the vaccine could afford useful protection for lambs against H. contortus.     

Protein requirements of Texel crossbred lambs

A comparative slaughter trial was conducted to determine the protein requirements for maintenance and growth of feedlot Texel crossbred lambs. Thirty 11/16 Texel × 5/16 Ile de France crossbred noncastrated male lambs weaned at 42 days of age (16.2 ± 2.1 kg of shrunk body weight; SBW) were used. Five lambs were chosen randomly and slaughtered after 10 days of experimental management and diet adaptation (baseline group). Fifteen lambs were fed ad libitum and slaughtered at 25, 30 or 35 kg of SBW. The remaining 10 lambs were then assigned randomly to two levels of dry matter intake, either 70 or 55% of the ad libitum intake, and were slaughtered concomitantly with lambs slaughtered at 35 kg of SBW but given free choice access to feed. Total body N content and retention were determined. Additionally, six Texel × Ile de France crossbred lambs (30.4 ± 2.6 kg of SBW) housed in individual metabolic cages were used in a replicated 3 × 3 Latin square digestibility trial to evaluate diet digestibility and microbial protein synthesis at the different levels of feed intake. The endogenous N loss was 243 ± 29 mg/kg^0.75 of SBW, corresponding to a net protein requirement for maintenance of 1.52 ± 0.18 g/kg^0.75 of SBW. The metabolizable protein (MP) requirement for maintenance was 2.31 g/kg^0.75 of SBW, and the efficiency of MP use for maintenance was 0.66. Fleece-free body protein content decreased from 163 to 155 g/kg of empty body weight (EBW) as EBW increased from 13 to 28 kg. However, when protein in fleece was considered the whole-body protein content remained nearly constant. Net protein requirements for body weight gain and wool growth of lambs at 15 and 35 kg of SBW, and an average daily gain of 250 g, were 28.7 and 27.3 g/day and 3.8 and 5.8 g/day, respectively. Estimated efficiencies of MP use for body weight gain (k_pg) and wool growth (k_pw) were, respectively, 0.71 and 0.46. Growth pattern of the wool has a high influence on protein requirements of lambs. Texel crossbred growing lambs used in our study showed protein requirements for growth lower than those reported by the most nutritional systems.     

Effect of suplemental nitrogen source and feeding frequency on nutrient supply to lambs fed a kikuyu grass (Pennisetum clandestinum) hay-based diet

Eight castrated male lambs (35 ± 4 kg live weight), fed a basal diet of kikuyu grass hay, were used in a replicated 4 × 4 Latin Square experiment with a 2 × 2 factorial arrangement of treatments to evaluate the effect of supplemental feeding frequency and source of rumen degradable N on intake, digestibility, ruminal fermentation, and microbial protein yield. Treatments were supplementation with cassava meal plus calcium caseinate or cassava meal plus urea offered at a rate of 7 g/kg live weight daily in one or two meals per day. Lambs were fed twice daily in such manner to allow ad libitum comsumption of forage. There was significant feeding frequency by N source interaction on variables of intake. In general, intake of feed components was higher (P ≤ 0.05) by lambs offered the caseinate-supplement twice daily over intake observed in lambs given the others diet treatments. Digestibility of feed components was neither affected by supplemental N source (DM, P = 0.541; OM, P = 0.585; NDF, P = 0.828) nor by feeding frequency (DM, P = 0.122; OM, P = 0.175; NDF, P = 0.591). Urinary excretion of N increased (P ≤ 0.05) in lambs supplemented twice daily whereas N retention was similar for all treatments (N source, P = 0.748; feeding frequency, P = 0.418). Microbial protein entering into the small intestine was affected by the interaction between feeding frequency and N source such as an increasing (P < 0.10) in this variable was observed when lambs received the caseinate but not the urea supplement twice daily. Efficiency of microbial protein synthesis, however, was not affected by treatments (N source, P = 0.588; feeding frequency, P = 0.334). Rumen pH averaged 6.70 and it was neither affected by N source (P = 0.827) nor by feeding frequency (P = 0.740). Ruminal concentration of ammonia N was not affected by feeding frequency (P = 0.144) while it increased (P < 0.05) when urea rather than caseinate was the supplemental N source (mean of 7.61 mg/dl vs. 6.00 mg/dl). Concentration of sugars in rumen fluid was higher (P ≤ 0.05) in lambs supplemented once a day compared to twice daily (mean of 49.4 mg/dl vs. 34.4 mg/dl) for both N sources. A significant (P ≤ 0.05) N source by feeding frequency interaction effect was observed for ruminal concentrations of α-amino N compounds. In urea treatment α-amino N concentration increased (P ≤ 0.05) in lambs receiving the supplement twice daily compared to once a day (mean of 4.59 mg/dl vs. 3.70 mg/dl) while in caseinate treatment it was higher (P ≤ 0.05) in lambs offered the supplement in one meal per day compared to twice daily (mean of 5.29 mg/dl vs. 4.07 mg/dl). In conclusion, for ruminants fed a tropical grass-based diet, starch-rich supplement containing non-protein N as N source may be offered only once a day whereas the supply of nutrients may be improved if degradable true protein is included as N source and supplement is offered in two meals per day.     

Winter grazing of reindeer in woodland lichen pasture: Effect of lichen availability on the condition of reindeer

Winter grazing of semi-domesticated reindeer (Rangifer t. tarandus) was investigated at the woodland lichen pasture (lichen approximately 550 kg DM ha⁻¹) in Kaamanen, northern Finland during the winter 1996–1997. Nine female reindeer mainly dug their food in the snow for 122 days (3 December–4 April) in a fenced area of 36.3 ha. Over half of the fenced area was lichen dominated dry pine forest. The amount of lichens in lichen forest inside the fence was estimated before and after grazing. Area of grazed and condition of reindeer as well as snow conditions were monitored. Reindeer grazed over the whole area of lichen forest in early winter but from mid-winter they tended to graze on the areas with the greatest lichen abundancy. The amount of lichens measured decreased in the latter areas by 40% and in the other part of the lichen pasture by 17%, respectively. In both of these areas the residual amounts of lichens left after grazing were similar. Of the dominant lichens, the amount of C. stellaris decreased the most and the amount of Cl. uncialis the least. During the study, the estimated average daily area grazed varied from 4 to 87 m² per reindeer. It was calculated that individual reindeer obtained 2.6 kg of lichen DM per day during the most intensive digging period when the body condition score and weight of reindeer increased. Otherwise, the body condition score and weight decreased. Reindeer finished foraging for ground lichens and started to search for arboreal lichens in mid-March when the snow layer was 70–80 cm thick and contained some hard snow layers which lifted reindeer. Both the amount of lichens in the pasture and the snow conditions essentially affect the nutritional status of reindeer in the woodland region during winter. Assuming that a reindeer is able to graze around 30 m² per day in the snow during mid and late winter, there should be, on the basis of energy demand and grazing behaviour of reindeer as well as the nutritive value of lichen, an estimated 1000 kg lichen DM ha⁻¹ available in a good condition woodland lichen pasture.     

Fatty acid profiles,growth, and immune responses of neonatal lambs fed milk replacer and supplemented with fish oil or safflower oil

Diets supplemented with long chain, n − 3 polyunsaturated fatty acids (PUFA) have improved the health and performance of neonatal and growing animals. This study was conducted with lambs that were orphaned at approximately 1 day of age to determine whether supplementing milk replacer fed lambs with oils rich in long chain n − 3 or n − 6 PUFA would alter plasma lipid profiles and affect growth characteristics and immune functions. From days 1 to 28 of age, lambs had ad libitum access to commercial milk replacer. From days 7 to 28 of age, lambs received twice daily either 1 g of soybean oil, 1 g of fish oil, or 1 g of safflower oil per os in a gelatin capsule (n = 60 pens; 20 pens/treatment; one ewe and one ram with similar initial body weights/pen). On days 7, 14, 21, and 28 of age, lambs were weighed, and jugular blood was collected from ram lambs. Lymphocyte proliferation in vitro, differential white blood cell (WBC) counts, and weight gains were quantified. Plasma from days 7 and 28 was used for fatty acid analyses. Fish oil increased (P < 0.001) plasma total n − 3 fatty acid concentration and total n − 3:total n − 6 fatty acid ratio. Pen body weight (i.e., total lamb weight per pen) increased (P < 0.001) with day (day 7, 11.9 kg; day 14, 15.1 kg; day 21, 18.2 kg; and day 28, 21.2 kg), but oil treatment did not affect pen body weight. Neither oil treatment, day, nor oil treatment × day interaction were significant for pen body weight gains (3.5 kg), pen average daily gains (0.5 kg), pen milk intakes (19.0 kg), or pen gain:feed ratio (0.18) measured during three intervals: days 7–14; days 14–21; and days 21–28. Day, but not oil treatment, affected (P < 0.001) unstimulated, concanavalin A stimulated, and lipopolysaccharides stimulated lymphocyte proliferation: days 14, 21, and 28 proliferation > day 7 proliferation. For neutrophils per 100 WBC, the treatment × day interaction was significant (P < 0.05). Oil treatment and day affected (P < 0.01 and <0.05, respectively) lymphocyte numbers per 100 WBC. For monocytes, eosinophils, and basophils, neither oil treatment, day, nor the oil treatment × day interaction were significant. Fish oil altered plasma fatty acid profiles, but it did not seem to improve measures of the performance or immune function of healthy, milk replacer fed lambs.     

Production efficiency and feeding behavior of Awassi lambs and Baladi kids fed on a high concentrate diet

Fifteen Awassi lambs and 15 Baladi kids (males, averaging 14.3 kg) were used to study the differences in feeding behavior and performance of sheep and goats fed a concentrate finishing diet (CP = 16 kg/100 kg DM, ME = 2.85 Mcal/kg DM) in a complete randomized design experiment lasting 60 days. Dry matter (DM) and organic matter (OM) intakes were significantly (P < 0.05) higher in lambs. Kids had higher (P < 0.05) apparent OM, crude protein (CP) and gross energy digestibilities. No significant (P > 0.05) differences were observed in apparent neutral detergent fiber (NDF) digestibility, eating, chewing and ruminating times. However, eating and ruminating times (as min/kg NDF intake) was significantly (P < 0.05) higher in kids. Final body weight and average daily weight gain were significantly (P < 0.05) higher in lambs while kids had significantly (P < 0.05) lower feed to gain ratio. Feed cost per kilogram weight gain for kids was better than that for lambs. Results demonstrated that Awassi lambs consumed more feed and grew faster than Baladi kids. However, kids were more efficient feed converters than lambs.     

Effect of different levels of concentrate allowances on rumen fluid pH,nutrient digestion,nitrogen retention and growth performance of weaner lambs

This experiment was conducted for 90 d to assess the effect of feeding graded levels of concentrate allowance on rumen fermentation characteristics, performance and nutrient utilisation of weaner lambs on restricted or high concentrate allowance using 60 weaner lambs of initial average live weight of 13.90 kg BW in a randomized design. The experimental treatments were 15 or 25 g kg⁻¹ BW or ad libitum concentrate allowance. Roughage source which contained Khejri (Prosopis cineratia) and Siris (Albizia lebback) leaves in 50:50 ratio was offered ad libitum to all the animals. Lambs supplemented with 15 g or ad libitum concentrate had similar dry matter intake (4.2 kg/100 kg BW) but significantly (p < 0.01) lower than 25 g concentrate supplemented group (4.9 kg/100 kg BW). Organic matter and CP intakes increased with increasing concentrate supplementation. Apparent digestibilities of dry matter, organic matter, CP, NDF, ADF and cellulose were significantly (p < 0.01) higher in ad libitum concentrate supplemented than 15 and 25 g concentrate supplemented lambs. Daily ME intake was significantly (p < 0.05) higher in 25 g and ad libitum concentrate supplemented lambs while ME intake kg⁻¹ gain was lower in ad libitum concentrate supplemented lambs (57 MJ kg⁻¹ gain) than those supplemented with 15 or 25 g concentrate (91 MJ kg⁻¹ gain). Generally, average daily gain increased with increasing levels of concentrate supplementation. Ad libitum concentrate supplemented lambs had significantly (p < 0.01) higher daily gains (151 g) than 15 and 25 g concentrate supplemented lambs (77 and 98 g, respectively). Feed efficiency was similar for 15 and 25 g concentrate supplemented lambs but significantly (p < 0.01) lower than the ad libitum concentrate supplemented lambs. All animals were in positive N-balance and the N-balance increased with increasing concentrate supplementation. Mean rumen fluid pH was significantly (6.6, p < 0.01) lower in ad libitum concentrate supplemented lambs compared to 15 or 25 g concentrate fed lambs (6.9). Rumen NH₃-N and total-N-concentrations peaked at 3 h post-feeding. Optimum rumen fluid pH, better nutrient digestibilities, higher N-retention improved growth by 49% of ad libitum concentrate fed lambs.