J. F. Aguilera

The effect of dietary protein content and feeding level on the rate of protein deposition and energy utilization in growing Iberian pigs from 15 to 50 kg body weight.

The effects of dietary protein content and feeding level on the utilization of metabolizable energy (ME) and on the rates of gain, protein and fat deposition have been studied in seventy-two Iberian pigs growing from 15 to 50 kg body weight (BW) by means of comparative slaughter experiments. The animals were fed on six diets providing 223, 192, 175, 156, 129 and 101 g crude ideal protein ( CP)/kg DM and 14.64, 14.14, 14.37, 14.80, 15.36 and 15.53 MJ ME/kg DM respectively. Each diet was offered at three levels of feeding: 0.60, 0.80 and 0.95xad libitum intake. Protein deposition (PD) increased significantly (P<0.01) with each decrease in dietary CP content and reached a maximum value (74.0 g) when the diet providing 129 g CP/kg DM (6.86 g digestible ideal protein/MJ ME) was offered at the highest feeding level. This feeding regimen resulted in average values for live-weight gain and retained energy (RE) of 559 g/d and 10.9 MJ/d respectively. RE increased significantly (P<0.001) from 480 to 626 kJ/kg BW0.75 with each decrease in dietary CP content from 192 to 129 g/kg DM. Raising the level of feed intake led to significant linear increases in PD and RE irrespective of the diet fed (P<0.001). When diets approaching an adequate supply of CP were given, the net efficiency of use of ME for growth (kw) and the maintenance energy requirements were 58.2 % and 422 kJ/kg BW0.75 per d respectively.

Protein and energy requirements for maintenance of indigenous Granadina goats.

Sixteen adult castrated male goats of the Granadina breed, with initial live weights ranging from 26.0 to 33.3 kg were used in two experiments to determine their protein and energy requirements for maintenance. Digestibility, nitrogen and energy balance measurements were made during the experiments. Two diets, which were based on pelleted lucerne (Medicago sativa) hay alone or on this forage and barley, were individually given at about maintenance level once daily. Gas exchange was measured using open-circuit respiration chambers. Fasting heat production was also determined. By regression analysis endogenous urinary N and maintenance requirements for N were estimated to be 119 mg/kg body-weight (W)0.75 per d and 409 mg total N/kg W0.75 per d respectively. Fasting heat production was 324 kJ/kg W0.75. The energy requirement for maintenance was calculated by regression of energy balance on metabolizable energy (ME) intake and a value of 443 kJ/kg W0.75 per d was found. The overall efficiency of utilization of ME for maintenance was 0.73.

Protein and energy metabolism of lactating Granadina goats

Twelve goats of the Granadina breed in mid- and late lactation were used in two consecutive years to determine their protein and energy requirements for lactation. The animals were individually fed on diets based on pelleted lucerne (Medicago sativa) hay and barley. A total of six balance experiments were carried out. Gas exchange was measured using open-circuit respiration chambers. Milk yield ranged widely from 0.649 to 1.742 kg/d in the first year and from 0.222 to 1.989 kg/d in the second year, a steady decline in milk output being observed as lactation progressed. Milk composition remained rather constant during the midstage of lactation, with an average content (/kg milk) for total solids, total nitrogen, fat and gross energy of 149.7 g, 5.39 g, 58.8 g and 3.59 MJ respectively. Total endogenous N, endogenous urinary N and maintenance requirement for N in lactating goats were estimated to be 244, 218 mg N/kg body-weight (W)0.75 per d and 478 mg total N/kg W0.75 per d respectively from regression equations. A constant efficiency of use of dietary N for milk N plus retained N of 51.0% was found. By regressing milk energy plus apparent body energy retention or loss on metabolizable energy (ME) intake, the maintenance energy requirement was estimated to be 401 kJ ME/kg W0.75 per d. When estimating the corrected milk yield as milk energy + (0.84 x negative energy retentio) + (1.05 x positive energy retention), regression analysis indicated that the overall efficiency of use of ME for lactation was 66.7%. Also, from a plot of apparent body energy retention v. milk energy yield, both expressed as a percentage of ME intake above maintenance, the efficiency with which ME was used to promote energy retention in the body during lactation was calculated to be 0.907 times that for milk secretion.

A comparative study of nutrient digestibility, kinetics of digestion and passage and rumen fermentation pattern in goats and sheep offered medium quality forages at the maintenance level of feeding

The in vivo digestibility and the rates of degradation and passage of alfalfa hay (AH) and vetch straw (VS) were compared in three Granadina goats and three Segureña wethers fed at approximately maintenance level, using a change over design. The nylon bag technique was used to estimate the fractional rate of degradation of the feeds in the rumen. The fractional outflow rate of hay and straw particles was determined with chromium as a marker. No significant differences in the digestibility coefficients of nutrients between animal species were found. Nitrogen retention expressed as coefficients of both nitrogen intake and digested nitrogen was lower (P < 0.01) in goats than in sheep when VS was offered. There was no significant difference between goats and sheep in the effective degradability (measured at outflow rates in the range of 0.027 to 0.032 h-1) of dry matter (DM) for either forage. However, the effective degradabilities of the neutral detergent fibre (NDF) and crude protein (CP) of VS were lower (P < 0.01 and P < 0.001, respectively), in goats than in sheep. The degradation rates of DM, NDF and CP were not significantly different (P > 0.05) between goats and sheep. Also, the fractional rate of passage of particles from the rumen was not different (P = 0.056) between species, although there was a tendency for an increased outflow rate in goats. In a second experiment the effects of animal species, type of diet and frequency of feeding on rumen fermentation pattern were studied following a factorial design. Four goats and four wethers were used. They were randomly allocated to three dietary treatments: AH, VS or a 50:50 mixture of AH and VS (AH/VS). Rations were offered in two or three meals daily and samples of rumen content were obtained at 09.00, 11.00, 13.00, 15.00, 17.00 and 19.00 h. No difference in rumen pH was found between goats and sheep. Total volatile fatty acids and ammonia concentrations were higher (P < 0.001) in sheep than in goats. The molar proportions of acetate and isovalerate were higher (P < 0.01 and P < 0.001, respectively) in goats than in sheep, whereas the opposite was true for the molar proportion of n-butyrate. Feeding frequency had a slight effect on the rumen parameters measured. It is concluded that only minor differences in the digestive capacity and rumen activity of sheep and goats can be expected when they are fed on medium quality forages.

Amino acid availability and energy value of acorn in the Iberian pig

Abstract Two experiments have been performed to determine amino acid digestibility and energy value of acorn (Quercus rotundifolia L.) for Iberian pigs. In experiment 1 ileal digestibility of amino acids was determined in five ileum-cannulated growing pigs fed whole ground acorn. An estimation of endogenous protein losses was carried out by feeding a protein-free diet, added (180 g/kg) or not with acorn hulls. True ileal digestibility of all essential amino acids measured was high (0.798–1.03) except for arginine (0.523), lysine (0.601), isoleucine (0.760), leucine (0.777) and phenylalanine (0.716). The average value for the digestibility of the sum of amino acids was 0.664. Lysine was the first limiting amino acid compared with the amino acid profile of the ideal protein for pigs. In experiment 2, total tract digestibility of nutrients and N balance were determined in five, non-cannulated pigs offered whole acorns. High coefficients for the apparent total tract digestibility of dry matter (ApDM) (0.830) and energy metabolizability (ME/GE; 0.805) were found. ME content for acorn kernel was 16.6 MJ/kg DM, while the apparent total tract digestibility of total N (ApTN) was as low as 0.408. However, a positive N retention was observed (3.7 g/day). Comparing experiments 1 vs. 2, inclusion of acorn hulls resulted in a marked decrease in DM intake, ApTN and in N retention (−5.1 g/day, in total tract data from experiment 1). The negative effects of acorn hulls on protein digestibility and N balance were corroborated in rats given similar amounts of either whole ground acorn or ground acorn kernel. Dietary supplementation with lysine is proposed to achieve a higher efficiency of protein accretion in the Iberian pig when fed on acorn.

The degradability of legume seed meals in the rumen: effect of heat treatment

The extent and rate of degradation of dry matter and nitrogen in ground seeds of pea (Pisum sativum), lupin (Lupinus albus var. multolupa), field bean (Vicia faba var. minor), vetch (Vicia sativa) and bitter vetch (Vicia ervilia), previously autoclaved (A) or not (NA) at 120 °C for 30 min, was measured using nylon bags incubated in the rumen of wethers fed lucerne hay. The fractional outflow rate of the legume seed meal particles was determined with chromium as a marker. More than 88% of the protein in untreated legume seed meals, except for vetch, disappeared from the bags by 24 h. Autoclaving decreased both the soluble fraction and the fractional rate of protein degradation of the slowly degraded fraction (P < 0.01). Rumen outflow rate was, respectively, 0.0154 h−1 and 0.0222 h−1, at 0.7 times and 1.0 times maintenance level. Effective degradability of protein was strongly reduced by heat treatment in pea and lupin seeds, moderately decreased in field bean and bitter vetch and almost unchanged in vetch seed meal.

Amino acid ileal digestibility of some grain legume seeds in growing chickens

The apparent and true amino acid (AA) digestibility from soya-bean meal (SBM), vetch meal (VM), field pea meal (FPM) and bitter vetch meal (BVM) were determined in the lower ileum of growing chickens force-fed on semisynthetic diets (120 g crude protein and 13·1 MJ metabolizable energy per kg dry matter) based on each meal as the sole source of protein. The average apparent and true digestibility values were 0·82, 0·73, 0·76 and 0·60 and 0·90, 0·91, 0·87 and 0·74 for diets SBM, VM, FPM and BVM, respectively. Marked differences in AA digestibility among diets were found. The apparent digestibility of methionine, the most limiting essential AA in poultry diets, was significantly higher in diet SBM than in diets FPM and BVM ( P

The energy costs of walking on the level and on negative and positive slopes in the Granadina goat ( Capra hircus )

The energy expenditure of six goats averaging 35 (SE 0.3) kg was measured when the animals were standing or walking on a treadmill enclosed in a confinement-type respiration chamber at different speeds (0.167, 0.333 and 0.500 m/s) and slopes (-10, -5, 0, +5 and +10%). The energy costs of locomotion, estimated from the coefficients of linear regressions of heat production (HP) per kg body weight v. distance travelled were 1.91, 2.33, 3.35, 4.68 and 6.44 J/kg BW per m for -10, -5, 0, +5 and +10% inclines respectively, indicating that the energy expenditure of walking over standing changes with slope according to a slightly curvilinear relationship. The energy cost of raising 1 kg body weight one vertical metre was found to be 31.7 J, giving an average efficiency for upslope locomotion of 30.9%. The energy recovered on vertical descent was estimated as 13.2 J/kg per m, indicating an efficiency of the energy recovered above the theoretical maximum.

Effects of dietary protein content and feeding level on carcass characteristics and organ weights of Iberian pigs growing between 50 and 100 kg live weight

The effects of dietary protein content and level of feeding on carcass characteristics and organ weights were studied in castrated male Iberian pigs growing from 50 to 100 kg live weight (LW). Animals were offered four diets providing 145, 120, 95 and 70 g ideal crude protein (CP) per kg dry matter (DM) and 13·94, 14·29, 14·56 and 14·83 MJ metabolizable energy (ME) per kg DM, respectively. Three levels of feeding were assayed: 0·60, 0·80 and 0·95 of ad libitum intake. The pigs were slaughtered at 100 kg LW. Daily gain in carcass (carcass gain, g/day) and protein deposition (PD, g/day) in this component attained 76·2% and 78·8% of whole-body average daily gain and PD, respectively. Carcass gain improved with each decrease in dietary CP from 145 up to 120 g/kg DM and then levelled off. A small but significant effect of dietary CP on carcass composition was observed, due to an enhanced fat deposition in pigs fed the lowest protein content diet. Mean values of protein, fat, ash and water contents in the carcass were 101·8, 522·7, 27·6 and 353·7 g/kg respectively. PD in the eviscerated carcass was not affected significantly by dietary protein level but tended to reach a maximum value with the diet that provided 95 g CP per kg DM: 55·7 g/day at the highest feeding level assayed. Carcass energy retention (MJ/day) increased significantly ( P P P P

Description and function of an open-circuit respiration plant for pigs and small ruminants and the techniques used to measure energy metabolism

Two open-circuit respiration chambers intended for use in energy metabolism research with pigs and small ruminants (goats and sheep) have been built. The respiration plant is air-conditioned, the temperature and the relative humidity in the chambers can be regulated from about +10 to 31 degrees C and from 45 to 90% relative humidity. The flowmeters operate on the basis of pressure differences. CH4, CO2 and O2 are analysed according to physical principles. Several calibration tests of the whole system were carried out with satisfactory results. A detailed description of the respiration facility is presented.