Effects of partial replacement of concentrate with feed blocks on nutrient utilization, microbial N flow, and milk yield and composition in goats.

Two experiments were carried out to evaluate the effect of partial replacement of concentrate with 2 types of feed blocks (FB) on rumen protozoa numbers, nutrient utilization, microbial N flow to the duodenum, and milk yield and composition in goats. The concentrate included oat, corn grain, barley, soybean meal, salt, and vitamin-mineral mixture. The FB (types I and II) were composed of crude 2-stage olive cake (120 or 100g/kg), fava beans (0 or 400g/kg), barley (320 or 200g/kg), beet molasses (220 or 100g/kg), sunflower meal (180 or 0g/kg), quicklime (70 or 90g/kg), salt (60g/kg), urea (0 or 20g/kg), and vitamin-mineral mixture (30g/kg). In experiment 1, 6 adult, dry, nonpregnant, rumen-fistulated Granadina goats (46.9+/-2.15kg of BW) were used and 3 trials were carried out. In each trial, 2 goats were randomly assigned to receive 600g of alfalfa hay and 400g of concentrate (diet AC), 600g of alfalfa hay, 200g of concentrate, and FB I (diet ACBI), or 600g of alfalfa hay, 200g of concentrate, and FB II (diet ACBII) with 6 replications per diet. The FB were supplied ad libitum. The ratio of purine bases to N was higher in solid- and liquid-associated bacteria for FB goats than for AC goats. In experiment 2, 18 Granadina goats (39.6+/-1.89kg of BW) in the middle of the third lactation were used, and 3 trials were carried out by following a 3 x 3 Latin square experimental design. In every trial, 6 animals randomly received 1.0kg of alfalfa hay supplemented with 1.0kg of concentrate (diet AC) or 0.5kg of concentrate and FB I and II (diets ACBI and ACBII) with 18 replications per diet. The FB were supplied ad libitum. The intakes of organic matter and fat were higher with the AC diet than with the FB diets. The intake of acid detergent fiber was higher for FB-containing diets than for the AC diet. The neutral detergent fiber digestibility of FB diets was higher than that of the AC diet. Energy intake was higher for diets AC and ACBII than for ACBI. Microbial N flow was affected by diet. Milk yield was higher in goats fed the AC diet than in those receiving the FB diets. Conjugated linoleic acid content was higher in milk from FB than in milk from AC goats. Our study suggests that FB type II based on local ingredients could be used advantageously to reduce half of the amount of concentrate without detrimental effects on nutrient utilization, N value of the diet, and milk composition. The decrease of milk yield with ACBII compared with that obtained with the AC diet could be compensated by better quality of milk, decreased cost of feeding, and environmental advantage derived of including by-products in FB.

Nutritive evaluation of legume seeds for ruminant feeding.

Chemical composition, rumen degradability and the effect of particle losses, and intestinal digestibility of protein by using in situ-in vitro and in vitro techniques were stated for beans (Vicia faba), lupin (Lupinus albus), vetch (Vicia sativa) and bitter vetch (Vicia ervilia) and four diets including those legume seeds. In addition, the apparent digestibility of experimental diets was determined in goats. The legume seeds showed high protein content (206-319 g/kg dry matter). Effective degradability of protein for legumes and diets varied from 0.80 to 0.87 and 0.76 to 0.82, respectively, decreasing to 0.53-0.76 and 0.61-0.67, respectively, when particle loss was taken into account. Different intestinal digestibility values were obtained with both methodologies without significant relationship between them (y = 1.058-0.463x; R(2)=0.068; RSD = 0.140; p = 0.53). There were no differences in the apparent nutrients and energy digestibility among diets (p > 0.05). These legumes can supply rapidly degradable protein for microbial protein synthesis and contribute to the pool of amino acids available for the synthesis of milk protein and for retention in the body.

Nitrogen and energy utilization in lactating dairy goats fed diets with different legume seeds.

The N and energy utilization of diets with different legume seeds was analysed in lactating goats. Four isonitrogenous and isoenergetic diets were used and in each case 30% of the protein was supplied by one of four different legume seeds: lupins (L), faba beans (FB), bitter vetch (BV) and vetch (V). A group of eight Granadina goats, allocated to a replicated 4 × 4 Latin Square, were used. The N and energy utilization of the different diets may be considered adequate; milk N/intake N was approximately 0.20, milk N/N balance was approximately 0.50 and milk energy/metabolizable energy was approximately 0.30. Under similar N and energy intakes, faecal and urinary excretion of N and the quantities in milk did not vary significantly. However, the partition of the N balance between milk production and deposit within the body varied depending on the diet. Although this N available to the metabolism was the highest for the FB diet, the quantity of this directed to milk was the lowest. Finally, the faecal and urinary excretion with respect to the quantity directed to milk production did not vary significantly among the different diets.

Evaluation of the allergenicity of goat milk, cow milk, and their lactosera in a guinea pig model.

The object of this study was to determine the allergenicity of goat milk (GM) and cow milk (CM) and that of their respective lactosera (GML and CML), by in vivo and in vitro assays. Two systemic tests for anaphylaxis were carried out in guinea pigs, the animals being sensitized orally with the 2 types of milk and lactosera. Sera were taken from the orbital sinus of the experimental animals at 0 and 22 d of the experiment to perform the serological study and the passive cutaneous anaphylaxis test. For the latter, the guinea pigs were sensitized passively with antibodies against the 4 antigen solutions. Enzyme-linked immunosorbent assay and Western blot were used to determine the specific antibodies of the isotypes immunoglobulin G1 and immunoglobulin G(Fc) developed against the same 4 antigen solutions. From these anaphylaxis and antibody-production tests, it was concluded that GM is hypoallergenic when compared with CM. The lactosera produced more closely grouped results, with values always below those of the corresponding milk. None of the proteins in the 4 immunizing solutions were identified as being their main allergen. These results show the hypoallergenicity of GM versus CM, and also that both casein and lactoserum proteins may be responsible for allergy in each case. To analyze the possibility of producing an innocuous food for those allergic to milk proteins, it would be of interest to identify the epitope(s) responsible for such allergenicity.

Prevalence of Cryptosporidium infection in goats maintained under semi-extensive feeding conditions in the southeast of Spain.

The aim of the present study was to estimate the prevalence of Cryptosporidium parvum infection in goats maintained under semi-extensive feeding conditions in the southeast of Spain. Four farms took part in the study. Samples were obtained during the autumn and spring kidding seasons. The goats were divided into three groups: group I (0-15 days), group II (> 15 days-2 months) and group III (> 2 months-9 years). Faecal specimens were concentrated and smears of the sediment (25 microl) were stained by the modified Ziehl-Neelsen acid fast technique. Parasite oocysts were identified in all the farms; of the 582 goats, 111 were found to have the parasite in their faeces, i.e. the prevalence was 19.1%. The frequency distributions of the Cryptosporidium oocyst counts according to the age categories were 10.4%, 13.4% and 25.2% for groups I, II and III respectively. With respect to the kidding season, nodifferences were found. The present study revealed the high prevalence of Cryptosporidium infection in goats in the studied zone.

Nutritional utilization in Malagueña dairy goats differing in genotypes for the content of alphaS1-casein in milk.

A study was carried out with 20 goats of the Malagueña breed, half with a high (HG) and half with a low (LG) genetic capability for alpha(S1)-casein (AS1-CN) synthesis, to determine whether the 2 different genotypes (that cause differences in goat milk composition) are related to differences in nutritional feed utilization. Among the 10 HG goats, 7 had BB and 3 had AB genotypes for AS1-CN, whereas there were 7 EF and 3 FF genotypes in the 10 LG goats. The goats were fed diets differing in crude protein content (13.6 vs. 17.7% dry matter for diets 1 and 2, respectively). For each genotype group, a balance trial was conducted with each of the 2 diets in a 2-period balanced changeover designed with half the animals consuming diet 1 and the other half diet 2, determining individual feed intake and the utilization of N and energy in the diets. Greater voluntary feed intake on a metabolic body weight basis among the HG goats was identified as the first possible cause of their milk production. The HG goats also had a greater level of feed utilization, on a metabolic body weight basis, for N and energy intake. Greater ratios of N balance/ digestible N, milk protein N/digestible N, milk energy/ digestible energy, and milk energy/ME were found for HG goats compared with LG. These effects appear to be dependent on the level of protein in the diet, indicating interactive effects. The greater N and energy utilization of HG versus LG goats may explain the differences in milk composition between the 2 genotype groups.

Alternatives for improving physical, chemical, and sensory characteristics of goat cheeses: the use of arid-land forages in the diet.

To establish the effect of an alternative diet on the quality of Majorero cheese, the basic physicochemical parameters, fatty acid profile, and sensory characteristics were studied. Two groups of 20 Majorero goats were fed 2 different diets: a forage diet (DF), which had a high ratio of long fiber to concentrates (65:35), and a concentrate diet (DC), with a low ratio of long fiber to concentrates (35:65). The DF dietary fiber was supplied by native forages adapted to arid land. A total of 42 Majorero goat cheeses were used for this study: 21 in the DF group and 21 in the DC group. Seven cheeses from each group were tested after 2, 15, and 60 d of ripening. The milk produced by goats fed the DF diet had a higher fat concentration. No significant differences were observed in the milk fatty acid profile. The diet affected the chemical composition of the cheese in pH and fat content, and fat was significantly higher in cheeses made from DF milk than those from DC milk. Dietary characteristics had important effects on the medium-chain fatty acid composition (C6 to C14) of the cheese fat, giving DF cheeses the specific goat's milk flavor that is sought after for this type of cheese. The fatty acid composition (%) differed substantially among different ripening times. The DF cheeses were more appreciated by the panelists, as they had a greater variety of odors and flavors than the DC cheeses. The DF hard cheeses were described as having vegetable and fruity tones as well as tones of hay and dried fruit.

Polyunsaturated fatty acids and parasitism: effect of a diet supplemented with fish oil on the course of rat trichinellosis.

Dietary fish oil has a beneficial effect on heart and some bacterial diseases and apart from other effects, some studies have revealed their ability to modulate the course of inflammatory and autoimmune diseases. The study here reported was designed to evaluate the possible influence of a fish oil supplement on the course of a Trichinella infection. Nutritional, parasitological and immunological parameters were analyzed. Two groups of 20 Wistar rats, one fed a standard diet and the other one a standard diet supplemented with fish oil, were infected with 1000 L1 larvae. Other two uninfected groups served as control. Results were as follows: fish oil diet intake and infection have, respectively, a positive and a negative effect on growth and food utilization. The negative effect is detected later in animals fed the fish oil diet. A reduction of 30.9 and 36.6% in the number of adult worms and L1 larvae, respectively, was observed in the fish oil group as compared to the standard diet group. Production of IFNgamma (Th1 response) and IL4 (Th2) response was measured in stimulated splenic cells. The fish oil diet increased both IFNgamma and IL4 levels. At 6 days after infection both IFNgamma and IL4 responses were detected, but at 36 days after infection only IL4 was detected in the standard group. The level of somatic and cuticular antibodies was not affected by the diet.

Physiological responses of pre-ruminant kid goats and lambs to different environmental temperatures.

The purpose of this study was to establish the metabolic behaviour of both preruminant kid goats and lambs, when they are kept at different environmental temperatures (12, 24 and 30 degrees C). The animals were fed ad libitum with a milk replacer for the first two months of life. Blood samples were taken from all the animals on days 30, 40, 50 and 60 post partum, to determine serum levels of glucose, insulin, free fatty acids, triiodothyronine (T3) and thyroxine (T4), both when fasting and 4 hours after starting feeding. The high sensitivity of both kinds of animal to the lowest of the environmental temperatures used, particularly for the first periods of life here considered, was established from the glucose/insulin and T3/T4 molar ratios and from the concentrations of free fatty acids. The results obtained by species were also evidence of metabolic behaviour typical of leanner animals in kids.

Production of healthier goat milk. Use of a concentrate supplemented with a "protected" fat rich in PUFA.

In order to obtain healthier goat milk as far as its fat composition is concerned, milk production and composition trials were carried out with Granadina goats kept in semi-extensive breeding conditions. The animals were feeding indoors with a concentrate supplemented or not with 7% of fat conveniently protected against the action of rumen, which had 35% of polyunsaturated fatty acids (PUFA). The amount of milk produced was higher (p < 0.05) with consumption of the fat supplemented concentrate. At the same time, and although there was no difference in the milk concentration of fat and protein nitrogen (p > 0.05), the corresponding yields were higher for consumption of the fat supplemented concentrate. As for the composition of milk fat, the use of the supplemented concentrate resulted in fat with a higher (p < 0.05) concentration of PUFA and a lower (p < 0.05) concentration of stearic acid. At the same time, the concentration of medium chain triglycerides, which is the specific nutritional value particular to goats' milk, was the same whichever concentrate was consumed.

Factors affecting the food intake, growth and protein utilization in the Helix aspersa snail. Protein content of the diet and animal age.

Food intake, growth and protein utilization were studied in the Helix aspersa snail by means of a nutritional balance experiment. This was designed in a 5 x 11 factorial arrangement involving 5 diets of different protein content (10.0, 12.5, 15.0, 17.5 and 20.0%) and 11 animal ages (ranging over 15 to 180 days of age). Dietary protein content and animal age determined food intake and protein utilization. The variations of dry matter and protein intake rates, growth rates, growth efficiency factors and protein retention rates, depending on dietary protein content or animal age were in agreement with what happens in other animals. These results suggest that there is no need to use diets with more than 17.5% of crude protein in these animals.

Thermogenesis associated to the intake of a diet non-supplemented or supplemented with n-3 polyunsaturated fatty acid-rich fat, determined in rats receiving the same quantity of metabolizable energy.

The beneficial effects of n-3 polyunsaturated fatty acids (PUFA) are well known, but their consumption in western countries is chronically insufficient, and so it is recommended that diets should be supplemented with a fat rich in these fatty acids. However, the effect of such diets on the energy expenditure remains a controversial question. Precise data concerning the effect of using under the same metabolizable energy intake, a diet non-supplemented or supplemented with a fat rich in n-3 PUFA are not available. This type of information was obtained using rats at weaning fed a diet supplemented or non-supplemented with 10% of fish oil. Between the 30th and 60th day after starting the experiment, the energy and protein balance was established by means of the comparative slaughter method. The blood levels of different metabolites were also determined. Although total thermogenesis did not vary between the two groups, consumption of the fish oil diet led to a lower level of thermogenesis associated with the oxidation of protein, and a higher one of that associated with the oxidation of fat. We conclude that the thermic effect of feeding is a combination of independent processes. Due to their specific metabolism, n-3 PUFA may be considered essential compounds to maintain the energy balance.

Dietary factors affecting the maximum feed intake and the body composition of pre-ruminant kid goats of the Granadina breed.

An experiment was carried out with kid goats of the Granadina breed to identify the dietary factors affecting voluntary feed intake of the kid goat and those that additively could determine its body composition. The animals used were from birth to 61 d of age, fed ad lib. on different milk replacers containing 200, 240 and 280 g crude protein/kg DM and 200, 240 and 280 g fat/kg DM, thus giving nine dietary treatments. The utilization of the milk replacers and the animals' body composition were determined by balance and slaughter trials. There were significant positive effects of protein concentration of the milk replacers on component digestibilities, energy metabolizability, feed intake, empty-body weights, empty-body composition and protein and fat retention. The concentration of fat in the milk replacers also had a significant positive effect on the digestible and metabolizable energy concentration of the diets and on fat retention. The relationships existing between feed intake and diet composition (concentration of digestible protein, metabolizable energy and digestible protein:metabolizable energy ratio) as well as between empty-body composition or protein and fat retention and diet composition, were examined. From these it was deduced that feed intake was significantly influenced by the digestible protein concentration of the diets. The higher the digestible protein concentration the higher the feed intake up to a maximum digestible protein concentration value. As the digestible protein concentration of the diets was the dietary factor which significantly influenced feed intake, this also significantly influences the body composition and the protein and fat retention. The protein concentration of the feed at which metabolizable energy intake in these animals would be greatest was estimated to be 347 g/kg DM.

Forage of different physical forms in the diets of lactating Granadina goats: nutrient digestibility and milk production and composition.

To determine whether the energy balance of goats or characteristics of the diet consumed were the principal factors that determined milk production, feeding and digestion trials were carried out using two groups of 5 Granadina goats. The concentrate fraction of both diets was the same, but the forage fraction of the diets differed. In diet 1, the forage was in the form of long alfalfa hay, and, in diet 2, forage was in the form of pelleted alfalfa. Intake and the forage to concentrate ratio of the two diets were not significantly different, although diet 2 was more digestible. The amount of fat and protein in the milk depended on energy intake and not on dietary treatment. The milk protein of goats fed diet 2 was higher in casein. No sensible differences were noted in the fatty acid composition of the milk. Nitrogen and metabolizable energy utilization for milk production was greater for goats fed diet 2. According to the results obtained, it would seem advantageous to use pelleted alfalfa rather than alfalfa hay in the diets of goats.

Body composition of goat kids during sucking. Voluntary feed intake.

The body composition of thirty-eight Granadina goat kids was measured. Six animals were slaughtered at birth while the remainder were kept individually at an environmental temperature of 24 +/- 2 degrees and a relative humidity of 60 +/- 5%. They were given goat's milk or a milk-substitute at two planes of nutrition until 15 or 30 d of age and then slaughtered. The goat's milk and milk-substitute contained 260.4 and 222.0 g digestible protein/kg and 23.23 and 20.85 MJ metabolizable energy/kg respectively. Voluntary feed intake as metabolizable energy was a function of metabolic body-weight (kg W0.75), equivalent to 2.42 and 2.44 times the energy requirement for maintenance for goat's milk- and milk-substitute-fed animals respectively. There was a high degree of correlation between the empty-body concentration of dry matter, fat and energy and empty-body-weight (P less than 0.001) or animal age (P less than 0.001), and between body-weight and animal age (P less than 0.001). The relationships between empty-body composition and empty-body-weight were independent of type of milk or plane of nutrition. In contrast relationships between empty-body composition or empty-body-weight and animal age were affected by the type of milk and, over all, by the plane of nutrition. All these results show that in these animals any body-weight will have a similar composition, but it will be reached earlier or later depending on dietary regimen and always with the limitation of voluntary intake.

Dietary supplements for lactating goats by polyunsaturated fatty acid-rich protected fat. Effects after supplement withdrawal.

The objective of this study was to investigate the persistence of the effects of supplements after they were withdrawn. Two groups of 12 goats were maintained under semiextensive breeding conditions; they were fed indoors with a concentrate with alfalfa hay and olivetree leaves. Goats were in their sixth month of lactation at initiation of the study. During the first month of the trials, the concentrate supplied to the goats was either nonsupplemented (group 1) or supplemented with 9% polyunsaturated fatty acids (PUFA)-rich protected fat (group 2). After this period, the 2 groups were given the nonsupplemented until the average daily production of milk per animal within each group had decreased to 300 g or less. The fat supplementation supplied increased milk production and also improved fat and protein yield. These effects persisted after the supplement was withdrawn. The supplement, moreover, produced noticeable changes in the fatty acids profile of the milk fat, namely a reduction in the concentration of saturated fatty acids and an increase in that of PUFA. In contrast to the effects on milk production and on the yield of its main constituents, the effects on fat composition disappeared when the supplement was withdrawn.

Study of nutritive utilization of protein and magnesium in rats with resection of the distal small intestine. Beneficial effect of goat milk.

The search for diets to improve the nutritive utilization of protein and magnesium in malabsorption syndrome led us to study goat milk, because of its particular nutritional characteristics, and to compare it with cow milk, which is most commonly consumed. We studied the nutritive utilization of protein and magnesium in transected rats (control) and in rats with resection of 50% of the distal small intestine. The diets used were the standard diet recommended by the American Institute of Nutrition and diets based on lyophilized goat or cow milk. The consumption of goat milk produces better protein efficiency ratio and food conversion efficiency values, particularly in rats with intestinal resection, together with a higher nutritive utilization of protein. Magnesium apparent digestibility coefficient is not modified by intestinal resection in rats fed with goat milk-based diet, on the contrary to the standard and cow milk diets. Magnesium apparent digestibility coefficient is greater for the goat milk group, which is reflected in the greater quantity of this mineral stored in bone. These results demonstrate the beneficial effect of goat milk on the nutritive utilization of protein and on magnesium bioavailability, especially in animals with resection of the distal small intestine.

Use of different dietary protein sources for lactating goats: milk production and composition as functions of protein degradability and amino acid composition.

To establish the effect of the nature of four different protein sources [fababeans, 27.8% crude protein (CP); sunflower meal, 41.7% CP; corn gluten feed, 18.8% CP; and cottonseed, 18.3% CP] on milk protein production by goats, the ruminal degradation of these feeds was studied as was the amino acid (AA) composition of the original material and that of the undegradable fractions of the protein sources. Four diets were designed; 20% of their protein was supplied by each of the different sources. Four groups of 5 Granadina goats were used to study the utilization of these diets for milk production. No significant differences were observed in dry matter intake or milk production. The milk produced by goats fed the diet containing sunflower meal had the lowest protein concentration; the highest milk protein concentration was observed for goats fed the diet containing corn gluten feed. From a multivariate analysis, it was deduced that the quickly degradable protein fraction in the rumen and the ruminally undegradable protein fraction were the components of the protein sources most directly related to the milk protein produced. Given the similar AA profiles of the undegradable fractions of the different protein sources, the possible supplementation achieved from these ruminally undegradable fractions must be established by the amount of protein supplied regardless of AA composition.

Beneficial effect of goat milk on nutritive utilization of iron and copper in malabsorption syndrome.

The search for diets that improve the digestive and metabolic use of iron and copper in malabsorption syndrome led us to study goat milk for particular nutritional characteristics and compare it with cow milk, which is usually supplied. We studied the metabolism of iron and copper in transected rats (control) and in resected rats (resection of 50% of the distal small intestine). The diets used were the standard diet recommended by the American Institute of Nutrition and diets based on goat or cow milk. Intestinal resection reduced the apparent digestibility coefficient (ADC) of iron in the three diets tested. In the transected and resected rats, the ADC of iron was highest with the goat milk diet, followed by the standard diet and lowest with the cow milk diet. The ADC of copper was not affected by intestinal resection in the animals fed the goat milk diet, and was higher than that in the two groups of animals fed the other diets. Intestinal resection reduced the ADC of copper with the standard diet and the cow milk diet. When both groups of animals were fed the goat milk diet, the deposit of iron in the organs was greater than with those fed the cow milk diet and similar to that in those animals given the standard diet. The copper content in the kidneys was lower in the resected than in the transected animals, except in the case of those fed the goat milk diet, in which it was similar to that of the control (transected) rats. This study shows the beneficial effect of goat milk, with respect to cow milk, on the metabolism of iron and copper in control rats, especially those with malabsorption syndrome.

Digestive utilization of goat and cow milk fat in malabsorption syndrome.

We studied the effects of goat and cow milk fat on the digestive utilization of this nutrient and on some of the biochemical parameters that are related to the metabolisim of lipids, using rats with a resection of 50% of the distal small intestine and control animals (transected). The fat content in all the diets was 10% but the lipid quality was varied: the standard diet was based on olive oil, while the other two diets included fat obtained from lyophilized goat milk and cow milk, respectively. The digestive utilization of the fat was lower in the resected animals than in the transected ones for all three diets studied. In both resected and transected animals. the apparent digestibility coefficient (ADC) of the fat was greater with the standard diet (olive oil) than with diets whose fat content was provided by goat or cow milk. The digestive utilization of the fat was greater in the transected and resected rats receiving a diet of goat's milk (rich in medium-chain triglycerides) than those given a cow-milk-based diet and more closely approached the values obtained for olive oil. The consumption of goat milk reduced levels of cholesterol while levels of triglycerides, HDL, GOT and GPT remained with in the normal ranges, for both transected and resected animals. The advantageous effect of goat milk on the metabolisim of lipids with respect to cow milk suggests that the former should be included in the diet in eases of malabsorption snydrome.