| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
ANIMAL PRODUCTION |
* Grup de Recerca en Remugants, Universitat Autònoma de Barcelona, Bellaterra, Spain;
and
Facultad de Veterinaria, Universidad de la República, Montevideo, Uruguay; and
and
UMR Élevage des Ruminants en Régions Chaudes, Campus ENSAM-INRA-PHASE, Montpellier, France
 |
Abstract |
|---|
 Top Abstract INTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
Key Words: digestibility • electronic identification • lamb • rumen bolus
|
INTRODUCTION |
|---|
|
TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
) for the current Spanish sheep and goat populations.
An e-ID bolus contains a passive transponder, which is orally administered and retained in the reticulorumen (Caja et al., 1997, 1999; Fallon, 2001). Bolus retention may vary according to its specifications (i.e., weight, o.d., specific gravity) as indicated by Caja et al. (1997, 1999) and Fallon (2001). Caja et al. (1999) reported a 100% retention rate in sheep when using 65 g (20 x 70 mm) ceramic boluses; but because of its dimensions, this bolus is only suitable for lambs heavier than 25 kg of BW. Considering that an earlier administration may be necessary, Garín (2002) and Garín et al. (2005) developed boluses of reduced dimensions (5.2 to 20.0 g; 9.3 x 37.4 mm to 15.0 x 39.4 mm). Boluses of 9.0 g (9.5 x 37.4 mm) were safely administered to 1-wk-old lambs, but retention rate through 1.5 yr was only 91.5%. Of those lost, 17.1% passed through the reticulo-omasal orifice and were located in the abomasum (Garín, 2002). No effects on lamb performance, reticulorumen development, or epithelium integrity were reported (Garín et al., 2003, 2005), but no information is available on the side effects of mini-boluses on diet digestion in fattening lambs.
The aim of this work was to test, for early identification of lambs, 3 mini-boluses that could be further retained in the reticulorumen of adult sheep and to evaluate the effects of the mini-bolus on feed intake and nutrient digestibility of lambs.
|
MATERIALS AND METHODS |
|---|
|
TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
Three types of cylindrical mini-boluses made of high-density zirconia (ZrO2), according to the patent by Caja et al. (2003), were evaluated. Mini-boluses were designed for early (i.e., before weaning) administration in lambs and for effective retention (i.e., >98%) in adult sheep, according to recommendations of the International Committee for Animal Recording (ICAR, 2005a).
The boluses were commercially produced (Rumitag, Esplugues de Llobregat, Barcelona, Spain), and their dimensions were B1 (weight, 13.8 ± 0.23 g; o.d. x length, 10.5 x 51.0 mm; specific gravity, 3.56 ± 0.02), B2 (16.2 ± 0.13 g; 12.2 x 42.2 mm; 3.59 ± 0.04), and B3 (20.1 ± 0.23 g; 11.2 x 56.4 mm; 3.91 ± 0.01), as shown in Figure 1. The lightest bolus was B1, the shortest was B2, and the longest and heaviest was B3.
|
All boluses contained 1 passive, half-duplex, glass-encapsulated transponder (32 x 3.8 mm; model Ri-Trp-RR2B-06, Tiris, Almelo, the Netherlands) and were machine-sealed with a food-grade silicon paste (Rumitag). Samples of each bolus type were tested and certified by the Tempest laboratory (Korn, 2004) in the Joint Research Center of Ispra (Italy). Transponders worked at a frequency of 134.2 kHz and agreed with the International Organization for Standardization (ISO) 11784 and 11785 standards (ISO, 1996a,b). The code of the transponders included the ICAR (2005b) manufacturer code of 0964 (Rumitag) and a 12-digit serial number.
Reading performances (>22 cm with handheld readers; >65 cm with static readers) agreed with recommendations of the technical guidelines for implementation of Regulation 21/2004 in sheep and goats in the European Union (SANCO, 2005). Handheld transceivers (Gesreader 2S ISO, Rumitag), certified by the Tempest laboratory (Korn, 2004), were used for all on-farm and slaughterhouse reading controls. Transceivers detected and stored transponder codes and time of data reading. Data were downloaded to a computer using the GesCon v. 1.4 software (Rumitag).
Animals and Management
Experimental and animal care procedures were approved by the Ethical Committee on Human and Animal Experimentation of the Universitat Autònoma de Barcelona. A total of 545 fattening lambs were used from 3 sheep breeds: Ripollesa (n = 274; a Spanish meat breed), Manchega (n = 129; a Spanish dairy breed), and Lacaune (n = 142; French dairy breed).
Lambs were born in the flock of the S1GCE (Servei de Granges i Camps Experimentals) of the Universitat Autònoma of Barcelona in Bellaterra (Barcelona, Spain). When births were recorded, newborn lambs were weighed, their navel was disinfected (2% iodine solution in ethanol 96%), and they were tagged in the right ear with a small plastic ear tag (E1, 2-piece, rigid, plastic, rectangular flaps; 1.5 g and 1.0 x 3.5 cm; Tip-Tag, Allflex-Azasa, Madrid, Spain), which was considered a temporary identification. A second ear tag, made of polyurethane and considered to be a permanent identification, was applied in the left ear (E2, 2-piece, flexible, plastic, tamper-resistant flaps; 4.1 g; and 3.8 x 3.5 cm; Rumitag) at the time of successful bolus administration.
Lambs suckled from their mothers overnight (1600 to 1000) and were creep-fed a commercial starter concentrate (OM, 94.0%; CP, 17.5%; ether extract, 4.9%; cellulose, 4.7%; as-fed; Raltec pelleted prestarter, Serveram, Vic, Spain) until weaning. Weaning occurred weekly. Ripollesa lambs were weaned when they weighed more than 12 kg of BW (~7 wk of age). Dairy breed lambs (Manchega and Lacaune) were weaned at 5 wk of age (approximately 12 kg of BW) after 1 wk of restricted suckling (2000 to 0700), in which the ewes were previously milked to encourage consumption of concentrate by the lambs.
After weaning, lambs were moved to straw-bedded fattening pens (0.5 m2/lamb), in groups of approximately 20, and fed a commercial concentrate (DM, 88.0%; CP, 18.1%; ether extract, 3.6%; NDF, 17.0%; DM basis; Fimsa, Tarragona, Spain), barley straw, and water ad libitum, until they reached 24 kg of BW. A total of 385 lambs were slaughtered (Ripollesa, n = 208; Manchega, n = 104; Lacaune, n = 73), and 144 ewe lambs were retained for the adult ewe flock (Ripollesa, n = 60; Manchega, n = 49; Lacaune, n = 35). Ewe lambs retained for breeding joined the adult ewe flock at 24 kg of BW and grazed (6 h/d) Italian ryegrass (Lolium multiflorum Lam.) as a group. After grazing, ewe lambs were penned separately indoors and supplemented (as-fed basis) with dehydrated alfalfa hay (0.5 kg/d) and whole barley grain (0.3 kg/d) until they reached 35 kg of BW. Any lamb that died during the experiment was sent to the Pathology Service of the Universitat Autònoma de Barcelona for necropsy, and the cause of death was recorded.
Bolus Administration, Reading, and Recovery Procedures
Bolus administration was attempted, as soon as possible after birth, by a trained operator in once-weekly sessions, during which lamb BW was recorded using an electronic scale (FX-31, Allflex N.Z., New Zealand). The bolus administration schedule followed the lamb birth order. Each lamb was restrained by securing its body between the crook of the arm and the hip of the operator. The operator used one hand to hold the lamb’s head in extension, to ensure the continuity between the oral cavity and the esophagus, and the other hand to administer the bolus. Half of the boluses were administered directly by hand, by pushing gently with the index finger, and the other half were administered by using a small balling gun (Rumitag; Figure 1
). The bolus was deposited in the posterior region of the oral cavity, and the lamb’s mouth was closed to induce the swallowing reflex, as indicated by Caja et al. (1999). If difficulties in swallowing or resistance to passage through the esophagus were detected, bolus administration was suspended and a new attempt was made the following week. Lambs with bolus administration problems were recorded and kept under observation for the following 24 h.
All boluses were read before and after administration, and after 24 h and 1 wk, to determine early losses. Time required for bolus administration was considered as the difference between the before and after administration reading times recorded by the handheld transceiver. Boluses were read when the BW were recorded weekly until the end of the fattening period (24 kg of BW) and to 35 kg of BW in the ewe lambs kept for breeding. Boluses of slaughtered lambs were read before leaving the farm, at the beginning of the slaughtering line, and after recovery by trained operators in the offal room of the slaughterhouse (Escorxador Sabadell, Sabadell, Spain).
The slaughterhouse processed approximately 200 lambs/h. Bolus location in the forestomachs was determined immediately after evisceration by direct palpation or with the help of a handheld transceiver, and boluses were removed manually by cutting the wall of the forestomachs. Diameter of the reticulo-omasal orifice in the forestomachs was measured after bolus recovery using a conical caliper calibrated to between 5 and 40 mm (precision, 2.5 mm). Readability of identification devices was estimated as the ratio between the number of readable devices and the total number of devices applied (Caja et al., 1999; Conill et al., 2000).
Digestibility Experiment
To evaluate the effects of mini-boluses on diet intake and digestibility, 12 male Manchega lambs were used. Lambs were weaned at 35 d of age, penned in 1 group, and gradually introduced to an intensive feeding regimen (concentrate and straw diets) over 1 wk. At 45 d of age (14.9 ± 0.6 kg of BW), lambs were divided into 2 groups and randomly assigned to 2 bolus treatments: control (without mini-bolus) and B2 mini-bolus. The B2 mini-bolus was chosen due to its intermediate dimensions.
Four lambs from each group were placed in digestibility crates and fed 2 fattening diets of pelleted concentrates formulated to obtain varying ruminal fermentation characteristics and ad libitum barley straw. Concentrate diets were high-barley (barley, 66.3%; corn, 6.0%; gluten feed, 8.0%; soybean meal, 13.4%; soybean hulls, 2.0%; animal fat, 0.9%; urea, 0.6%; and mineral and vitamin premix, 2.8%; as-fed) and high-corn (corn, 60.0%; tapioca cassava meal, 6.5%; gluten feed, 7.0%; soybean meal, 16.5%; soybean hulls, 4.0%; cane molasses, 2.1%; urea, 0.8%; and mineral and vitamin premix, 3.0%; as-fed). Both concentrates were isonitrogenous (18.2% CP, DM basis) and isoenergetic (1.8 Mcal of NEf/kg of DM). Feed offered was adjusted daily to 115% of the previous day’s intake, and fresh water was continuously available. Four lambs were kept in a reserve group in pens bedded with barley straw, fed ad libitum a 1:1 mixture of the experimental concentrates, and used to replace any lamb that did not adapt to the digestibility crates.
The experiment consisted of four 21-d periods, which included a 14-d adaptation period to the diet and 7 d of feed intake measurement and total fecal collection. Concentrates were assigned at random at the beginning of each period to lambs in each bolus treatment. One lamb in the control treatment and one lamb in the bolus treatment, fed the high-corn concentrate, showed a low intake during the adaptation of the second experimental period and were replaced by lambs from the reserve group. As a consequence, the adaptation period to the diets was extended an additional 7 d in all lambs. The removed lambs showed subclinical symptoms of acidosis. The permanent retention of the boluses in the reticulorumen of all bolus-treated lambs was ensured by weekly checking of bolus readability using a handheld reader (Gesreader, Rumitag).
Feed intake was calculated as the difference between the total amounts of daily DM offered and refused (precision, 10 g). Lambs were weighed (precision, 0.1 kg) weekly before offering the diet, and ADG and G:F were calculated. Feed, orts, and feces were collected daily, and a 10% sample was composited per lamb and period and stored (–20°C) until analysis. Samples were dried in a forced-air oven at 60°C for 96 h, ground through a 1-mm stainless steel screen (Cyclotec 1093 Sample mill, Tecator, Hogänäs, Sweden), and analyzed for DM (967.03) and OM (942.05) according to the AOAC (1995). The CP (984.13) content was determined by using a Kjeltec Auto 1030 Analyzer (Tecator). The method of Van Soest et al. (1991) was used to determine NDF (amylase added) and ADF on an ash-free basis using an Ankom Fiber Analyzer incubator (Ankom Technology, Fairport, NY). Apparent digestibility of each nutrient was estimated with the equation: (1 – excreted/ingested) x 100.
Statistical Analysis
Bolus and ear tag readability, bolus retrieval at slaughter, and location of the bolus in the gastrointestinal tract were analyzed with the CATMOD procedure (SAS Inst. Inc., Cary, NC). A logit model fit by the maximum likelihood (Cox, 1970) was chosen due to the discrete variables. Factors considered were identification device type, administration procedure, lamb breed, and device x breed interaction. Age and BW at bolus administration were analyzed by ANOVA using the GLM procedure of SAS. Factors considered were bolus type, lamb breed, and bolus type x breed interaction.
Feed intake and digestibility data were analyzed using PROC MIXED of SAS for repeated measures, with compound symmetry as the covariance structure. Fixed effects were bolus treatment, period, and type of concentrate; and animal was the random factor. Nonsignificant (P > 0.20) effects and interactions were removed from the final models. Means were separated using Tukey’s test, and significance was declared at P < 0.05.
|
RESULTS AND DISCUSSION |
|---|
|
TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
A total of 18 lambs (3.3%) of the 3 breeds (Ripollesa, n = 8; Manchega, n = 5; Lacaune, n = 5) died during the experiment. Deaths were not believed to be related to the administration of mini-boluses as concluded from the pathology reports (previous to bolus administration, 3; white muscle disease, 2; diarrhea, 4; pneumonia, 3; accident, 3; and unknown, 3), and their data were excluded from the study. Mortality rate was in the range of values previously reported for lambs of the same breeds under similar rearing conditions (Garín et al., 2003, 2005).
A total of 19 lambs (3.5%) of the different mini-bolus treatments (B1, n = 6; B2, n = 6; B3, n = 7) had difficulty swallowing the mini-bolus during one of the administration sessions, and the operator decided to interrupt the administration. Boluses were administered to these lambs the following week without difficulty. Nevertheless, 1 Lacaune (3 wk old, 9.3 kg of BW) and 1 Manchega (2 wk old, 9.5 kg of BW) showed profuse salivation, nasal discharge, panting, and depression after administration of the mini-bolus. The mini-boluses were readable and palpable in the neck of the lambs and visualized by x-ray as lodged in the esophagus. A flexible plastic tube of 12 mm o.d. and 600 mm length was used to gently push the bolus to pass toward the rumen and clear the esophagus.
Age and BW at bolus administration did not differ between dairy breeds (P = 0.45; data not shown), and their data were pooled. Age and BW at bolus administration differed markedly according to bolus type and breed class (dairy or meat) as shown in Table 1. An interaction between bolus type and lamb breed was detected (P < 0.01; data not shown). On average, lamb age (27.0 and 27.3 d) and weight (9.1 and 9.2 kg of BW) at administration did not differ in lambs receiving the B1 and B3 bolus, but lambs receiving the larger B2 bolus were older (32.5 d; P < 0.001) and heavier (11.1 kg of BW; P < 0.001) when the bolus was applied. In agreement with previous studies documenting ADG for nursing lambs (Torre, 1991; Flores, 2004; Garín et al., 2003, 2005), dairy lambs were bolused younger than meat lambs (23 vs. 35 d; P < 0.001). However, a greater BW was required in dairy vs. meat lambs (10.1 vs. 9.5 kg of BW; P < 0.001) to reach the same development in the oropharynx and esophagus for safe bolus swallowing.
|
and 3, respectively. Although on average the 3 mini-bolus types could be administered at 29 d of age and 9.8 kg of BW, 1.7% of dairy lambs (n = 3) and 39.5% of meat lambs (n = 73) required 1 wk more for the safe administration of B1 and B3. Compared with when B1 and B3 boluses were administered, 57.3% of dairy lambs (n = 55) and 52.8% of meat lambs (n = 47) required an additional 2 wk before the B2 bolus could be administered. A plateau was observed in the accumulated values of administration rate according to lamb age (Figure 2), indicating that most of them were bolused earlier than estimated by the average time indicated in Table 1. Such a plateau appeared earlier in dairy than in meat lambs, the latter being unable to safely swallow the mini-bolus until wk 7 of age. Values of successful bolus administration rate according to lamb weight also showed a marked plateau for both lamb breed classes (Figure 3) for which the complete administration was achieved before they reached 14 kg of BW.
|
|
and Garín et al. (2003, 2005) for 5.2- and 20-g mini-boluses, which were safely administered to lambs older than 8 d (>6.6 kg) and 46 d (>12.0 kg), respectively.
Administration difficulties encountered in our experiment (3.5%) were lower than the 15.6 to 16.7% difficulties previously reported by Garín et al. (2003, 2005) with 20-g boluses (15 mm o.d.) in Manchega and Lacaune lambs of 15 kg of BW. Our results indicate less esophageal damage in lambs than those reported by Macrae et al. (2003) after administering an even smaller mini-bolus (9 g; 10 x 40 mm) to heavier, 17 to 35 kg of BW and older (2 to 8 wk of age) Suffolk lambs. In their results, 32% lambs showed clinical signs of pharyngeal damage, and 21% of the mini-boluses were located in the retropharyngeal region and were removed by surgery; as a consequence, 4% of lambs died. An insufficiently trained or poorly skilled operator, as well as an inadequate restraining or neck positioning, may have caused these lamb damages. Stanford et al. (2001) also noted that Suffolk x Romanov weaned lambs that were lighter than 20 kg of BW were not able to swallow 69-g boluses (20 mm o.d.). On the contrary, no difficulties at bolus administration were reported by Caja et al. (1999, 2003) and Macrae et al. (2003) using 16- to 75-g boluses (12 to 21 mm o.d.) in sheep heavier than 25 kg of BW of different breeds.
According to our results, BW is a more reliable criterion and is preferred to age for bolus administration. The sequence order for early administration of mini-boluses in suckling lambs was B1, B3, and B2 for the breed classes used in this study. This ranking corresponds to the o.d. size of each mini-bolus (B1, 10.5 mm; B3, 11.2 m; and B2, 12.2 mm) and not to their length (B2, 42.2 mm; B1, 51.0 mm; and B3, 56.4 mm) or weight (B1, 13.8 g; B2, 16.2 g; and B3, 20.1 g).
Bolus administration time averaged 35 ± 1 s, which included time for restraining, bolus application, and typing and recording of the animal data; this time was not affected (P > 0.37) by mini-bolus type, lamb breed, sex, or administration procedure (hand or mini-bolus gun). Administration time obtained in this study was longer than the time measured by Caja et al. (1999) who recorded an average of 24 s in adult sheep, without including restraining time. These values are lower than the mean time reported in the IDEA project (Ribó et al., 2003) in which bolus administration in adult sheep and in replacement ewes required more than 2 min/animal. Although more care is necessary, administration of mini-boluses in young lambs seems to be easier and faster than in older sheep, which may be an added advantage.
With regard to the readability of plastic ear tags at the end of fattening period, only 3 (0.6%) losses of E1 were reported in the slaughtered lambs. Marked signs of infection were observed around the application orifice in many cases. Moreover, another 7 E1 (1.3%) could not be read at the end of fattening due to the damages caused by bites of other lambs, and 98.1% E1 were readable at the end of fattening period. No losses or relevant damages were observed in E2, which were 100% readable at the end of fattening period, although 12.5% of the ears showed marked signs of swelling and suppuration.
Mini-bolus retention until the end of fattening and beginning of breeding ranged between 95.2 and 100% according to type (Table 1). Two losses of B1 (2.3%) were reported at wk 3, coinciding with the physiological age (wk 3 to 8) at which time the effective functioning of forestomachs begins in lambs (Poe et al., 1969, 1971; Oh et al., 1972). No more losses were observed for B1 during the experiment, indicating that a critical period for mini-bolus retention occurs in the pre- to true-ruminant transition period. Similar results were reported in transition Manchega and Lacaune lambs (Garín et al., 2003). No losses were observed for B2 and B3 during the fattening period (retention rate, 100%), indicating that these type of mini-boluses were adequate for the identification and traceability of fattening lambs (<24 kg of BW).
From the end of fattening to the beginning of breeding, one B1 (2.7%) and one B2 (4.8%) mini-boluses were also lost, whereas no losses were observed in B3 boluses (retention rate, 100%). The AMLC (1995) and Garín et al. (2005) reported that bolus losses occurred in grazing cattle and sheep, respectively, when submitted to an abrupt change in feeding regimen. Therefore, the change in feeding in the ewe lambs may have contributed to bolus losses when they were weaned or introduced to grazing. Retention rates observed in our results (95.2 to 100%) were greater than the 59.0 to 100% obtained by Garín (2002) and Garín et al. (2003, 2005) with previous mini-bolus models (5.2 to 20 g), the smallest being designed in order to be applied during the first week of life. The new design of the 3 mini-boluses used in the current study proved to provide a clear increase in retention rates compared with Garín (2002) and Garín et al. (2003).
All boluses were recovered from the lambs at slaughter (Table 1). Most of the boluses were found in the reticulum (between 80.9 and 97.1%), varying the location in the forestomachs according to mini-bolus type (P < 0.05). The greatest recovery in the reticulum was obtained with B3 mini-boluses. These results agree with other values reported for different e-ID boluses in sheep (Caja et al., 1999; Garín et al., 2003, 2005). Although retained until slaughter, a total of 3 B2 (2.0%) were recovered from the abomasum (dairy lambs, n = 2; and meat lambs, n = 1; Table 1). A similar situation was reported by Garín et al. (2003), who suggested that ruminal motility resulted in the passage of the mini-boluses through the small diameter reticulo-omasal orifice. The diameter of the reticulo-omasal orifice, measured in our experiment, was on average 14.2 ± 0.1 mm for male and female lambs of the 3 breeds (n = 194), which is in the range of the values (12 to 15 mm) reported by Buéno (1975), and greater than the diameter of the 3 types of mini-boluses (10.5 < o.d. < 12.2 mm) administered to our lambs. This allows the possible passage of mini-boluses from the reticulum to the omasum, which may have produced the transit losses through the digestive tract.
In conclusion, B3 mini-bolus proved to be an efficient device (retention >98% according to the ICAR recommendation; ICAR, 2005a) for identification of lambs before weaning (recommended age > 1 mo; and recommended weight > 10 kg of BW). Effective retention (100%) of B3 mini-boluses until breeding (35 kg of BW) and location in the reticulum at slaughter (95.1%) were also positive indicators for predicting their retention in adult sheep, although this aspect should be tested in the future.
Digestibility Experiment
Effects of B2 mini-boluses on intake and digestibility of intensively reared lambs are summarized in Table 2. All B2 boluses were retained in the forestomachs of lambs throughout the experiment and were retrieved in the reticulum at slaughter. The macroscopic appearance of the reticulorumen of these lambs was considered to be normal as previously reported by Garín et al. (2003, 2005) with similar boluses.
|
), which were normal for the Manchega breed and agreed with previous values reported for the same breed and rearing conditions (Garín et al., 2003, 2005; Flores, 2004). Average values of concentrate:straw ratio (95:5) and G:F (0.287 kg of gain/kg of feed) were high and moderate, respectively, according to the lamb performances and feeding conditions used.
Diet digestibility values were in agreement with the high level of concentrate but did not vary between control and bolused lambs (Table 2; P > 0.05). Nevertheless, a tendency (P < 0.10) to improve digestibilities of the ADF fraction was observed in the bolused lambs, which agrees with the improvement of reticulorumen mucosa keratinization reported by Garín et al. (2003) in early bolused lambs. As expected, the effect of period was significant on most of the variables studied, with the exception of the barley straw intake (P < 0.06). Intake (P < 0.001) and G:F (P < 0.01) of concentrates, as well as ADG (P < 0.001) increased with the experimental periods, whereas all the digestibility coefficients decreased (P < 0.001), as shown for ADF (Figure 4). High-corn concentrate tended to increase intake (P < 0.06), G:F (P < 0.11), and digestibility of ADF (P < 0.07), OM (P < 0.10), and CP (P < 0.11), compared with high-barley concentrate. Interactions (P < 0.05) between bolus and concentrate type (higher straw intake in lambs with bolus in the maize-based concentrate), and bolus and period (lower decrease in digestibility with time in the bolused lambs) were also found. Both bolus interactions were considered as positive for the lambs and reduced the negative impact of the intensive diet used. In conclusion, no negative effects were observed on performance and nutrient digestibility of lambs administered the mini-bolus, which tended to improve fiber digestibility in intensive feeding conditions.
|
10 kg of BW is a safe management practice. This practice will not reduce growth performance, diet intake, or digestibility traits of intensively reared lambs until slaughtering.
|
Footnotes |
|---|
2 The authors appreciate the assistance of Ramon Costa and the crew of the S1GCE (Servei de Granges i Camps Experimentals) of the Universitat Autènoma de Barcelona; Joan Francesc Vilaseca of Rumitag (Barcelona, Spain); and Nic Aldam for the English revision of the manuscript.
3 Corresponding author: gerardo.caja{at}uab.es
Received for publication February 7, 2006. Accepted for publication August 1, 2006.
|
LITERATURE CITED |
|---|
|
TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
|---|
This article has been cited by other articles:
|
|
 |
|
  S. Carne, T. A. Gipson, M. Rovai, R. C. Merkel, and G. Caja Extended field test on the use of visual ear tags and electronic boluses for the identification of different goat breeds in the United States J Anim Sci, July 1, 2009; 87(7): 2419 - 2427. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Carne, G. Caja, J. J. Ghirardi, and A. A. K. Salama Long-term performance of visual and electronic identification devices in dairy goats J Dairy Sci, April 1, 2009; 92(4): 1500 - 1511. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
= dairy; and, • = meat). Bars are numbers of lambs per week. Circles and lines refer to administration rate.
