Prediction of feed intake in the Italian dairy sheep

Recommendations on feed intake for sheep are based on assessments of genetic types, feeding systems and environ- mental conditions that are very different from Italian ones. These considerations underline the need for intake data or models that derive from local trials. For this reason intake data of lactating and dry ewes, pregnant ewes, rams and growing lambs have been collected from selected literature based on sheep feeding trials mainly conducted on dairy breeds in Italy or in other Mediterranean countries. Equations and intake tables differentiated according to the physio- logical and productive categories, as well as feeding typology are reported. Particular consideration is given to pasture intake with supplementation, reporting three equations developed for three qualitative levels of the pasture, recogniz- able from the CP content of herbage: 16% DM. The equations include animal and pasture variables and supplementation, expressed as grams of CP given with feeds other than pasture. Only when pas- ture CP content is lower than 10% DM, supplement is not included in the equation, as no or negative substitution effect is expected

Traceability of pasture feeding using some fatty acids and spectrophotometric parameters in milk

Seventy-three cow milk individual samples deriving from seven farms with different feeding system (pasture, P vs. stall, S), were collected with the aim to trace pasture feeding from different milk characteristics. Samples were analyzed for: linoleic and linolenic acids, colour parameters (L*, b*, a* C and H) using a Minolta CM-2002 spectrophotometer; the integral value of reflectance spectrum between 530 and 450 nm was also calculated. The linoleic/linolenic acids ratio resulted significantly lower in P group (P<0.001), whereas yellowness (b*) and the absolute integral value resulted significantly higher in P group (P<0.001). Linoleic/linolenic acids ratio allowed the complete discrimination between feeding groups, whereas the integral value and yellowness allowed only a partial discrimination (respectively 90.4% and 79.5% of cases). However, a milk fatty acid composition is strongly dependent on fat intake, any additional fat inclusion in the ration can modify it, apart from pasture presence in the diet. On the contrary integral value and yellowness are strongly related to carotenoids pigments, recognized as biomarkers of fresh herbage in the diet. For these reasons, integrating linoleic/linolenic ratio and colour parameters in a principal components analysis, a complete discrimination between pasture and stall feeding was obtained, with a greater reliability of results due to the combination of milk characteristics associated to different sources of variation (fats intake and carotenoids intake)

Effect of sustained-release somatotropin on performance and grazing behavior of ewes housed at different stocking rates.

This study evaluated the effects of recombinant bovine somatotropin (bST; one injection of 320 mg per ewe) on milk production and composition and on the grazing behavior of multiparous ewes in the third to fourth lactation. Forty Comisana lactating ewes were divided into four groups: 1) untreated, grazing on natural pasture (botanical composition: 35% of Graminaceae, 49% of Fabaceae, 6% of Cruciferae, 10% of other families) at a low stocking rate (16 m2/d); 2) untreated, grazing at a high stocking rate (8 m2/d); 3) treated with bST, grazing at a low stocking rate; and 4) treated with bST, grazing at a high stocking rate. The diets of the ewes were supplemented with vetch and oat hay (500 g/d) and with concentrate (500 g/d). Treatment increased milk production (923.8 vs. 669.5 g/d) but had little effect on fat and protein contents. Administration of bST significantly increased herbage intake; the effect on intake was more marked at the high stocking rate. Under these grazing conditions, the treated ewes reduced selective intake behavior and, thus, achieved good feed intake despite the low biomass availability

The role of polymorphism at αs1-casein locus on milk fatty acid composition in Girgentana goat

Sixteen lactating Girgentana goats were used to evaluate the effect of polymorphism at αs1-casein locus on milk fatty acids composition. Animals, homogeneous for milk production, days of lactation and body weight, were divided into two groups: eight homozygous for strong allele (AA group) and eight homozygous for weak allele (FF group). The experimental diet, identical for the two groups, consisted of alfalfa hay (1.5 kg), whole barley, whole maize, pelleted sunflower and whole faba bean (0.5 kg each). In spite of identical selected diets, also in terms of fatty acids, milk fatty acid composition resulted different between the two groups. In particular, except for C8:0, short and medium chain fatty acids and odd chain fatty acids resulted in higher percentage in the AA group. Taking in account that the difference reported in our experiment concerns above all de novo synthesized fatty acids, our results seem to confirm the hypothesis that polymorphism at αs1-casein locus can influence milk fatty acid composition in goats

Models for estimating feed intake in small ruminants

This review deals with the most relevant limits and developments of the modeling of intake of sheep and goats reared intensively and extensively. Because small ruminants are normally fed ad libitum, voluntary feed intake is crucial in feeding tactics and strategies aimed at optimal animal production. The effects of genetic, neuroendocrine, hormonal, feed and environmental factors on voluntary feed intake were discussed. Then, several mathematical models to estimate dry matter intake (DMI) were examined, with emphasis on empirical models for sheep and goats in intensive farm systems or in extensive areas under pasture or rangeland conditions. A sensitivity analysis of four models of prediction of DMI in housed lactating dairy sheep and meat sheep breeds was also presented. This work evidenced a large variability in the approaches used and in the variables considered for housed sheep and goats. Regarding the estimation of feed intake for grazing sheep and browsing goats, the accuracy of estimates based on empirical models developed so far is very low when applied out of the boundaries of the studied system. Feeding experiments indoors and outdoors remain fundamental for a better modeling and understanding of the interactions between feeds and small ruminants. However, there is a need for biological and theoretical frameworks in which these experiments should be carried out, so that appropriate empirical or mechanistic equations to predict DMI could be developed

Inclusion of cocoa by-product in the diet of dairy sheep: Effect on the fatty acid profile of ruminal content and on the composition of milk and cheese.

Abstract In this study, we hypothesized that dietary cocoa bean shell (CBS) as a partial replacer of human edible cereal grains in the diet of lactating ewes may affect performance and milk and cheese composition. Twenty Comisana lactating ewes allotted into control (CTRL; n = 10) or cocoa (CBS; n = 10) group received alfalfa hay ad libitum and 800 g of conventional (CTRL) or experimental (CBS) concentrate containing 11.7% CBS to partially replace corn and barley of the CTRL concentrate. Milk yield and composition did not differ between groups, and only urea concentration was lower in CBS milk. Dietary CBS increased cheese fat and reduced protein percentage in CBS group. Fatty acid composition of rumen content partially reflected that of the ingested diet, with total saturated fatty acids (SFA), total monounsaturated fatty acids (MUFA), 16:0, 18:0 and 18:1c9 greater in the CBS group. Moreover, all the identified trans- and cis-18:1 isomers were greater in CBS rumen content. Milk and cheese showed a similar fatty acid composition. Total MUFAs were greater in milk and cheese of CBS, mainly due to the proportion of 18:1c9, and conversely, total polyunsaturated fatty acids (PUFA), PUFAn-6 and PUFAn-6-to-PUFAn-3 ratio was greater in CTRL group. Concluding, the inclusion of CBS in the diet of lactating ewes within the limit imposed by the current legislation did not cause detrimental effects on animal performance and milk composition. Interestingly, dietary CBS reduced milk urea concentration probably due to the phenols contained in CBS concentrate. However, our results support that biohydrogenation was weakly impaired by dietary CBS. Finally, CBS negatively affected cheese nutritional characteristics due to lower protein and greater fat content, but improved fat health indexes in milk and cheese

Genetic polymorphisms at candidate genes affecting fat content and fatty acid composition in Modicana cows: effects on milk production traits in different feeding systems.

Feeding greatly affects milk yield and composition. The research is highlighting the potential of genetic polymorphism at some loci to affect milk yield and quality traits. These loci can be up/down regulated depending on the production environment; therefore, we hypothesized that milk yield and composition could differ when cows with different genotype at SCD, DGAT1 and ABCG2 loci are reared in different feeding systems. The polymorphisms of SCD, DGAT1 and ABCG2 genes were investigated in Modicana breed. In all, three polymorphic sites, responsible for the genetic variation of quantitative trait loci and therefore defined quantitative trait nucleotides, were genotyped: the transition g.10329Cgt;T in 5th exon determines a substitution p.A293V in the SCD, the dinucleotide mutation g.10433-10434AAgt;GC in 8th exon responsible for p.K232A substitution in the DGAT1 and the transition g.62569Agt;C in the 14th exon responsible for p.Y581S substitution in the ABCG2 gene. In the sample of 165 Modicana cows, SCD and DGAT1 genes resulted polymorphic; the alleles g.10329T and g.10433-10434GC were the most frequent in SCD and DGAT1 (0.73 and 0.91) respectively, whereas ABCG2 locus was monomorphic for allele A (p.581Y). Sequencing analysis was carried out on 14 samples with different genotypes to confirm the results of the PCR-RFLP protocols. Based on the genotypes at SCD locus, 47 Modicana cows were selected for the nutritional trial: 24 cows in a semi-intensive farm, with 2 h/day grazing on natural pasture, and 23 cows in an extensive farm, with 8 h/day grazing on natural pasture. Monthly, milk yield and composition were evaluated and individual milk samples were analyzed for fatty acids composition by gas chromatography. No differences in milk yield, fat, protein, lactose, casein and urea were associated to SCD genotype. Feeding systems affected milk yield and composition. No significant genotype×feeding system interaction was observed for milk yield and composition. Fatty acids composition was significantly affected only by the feeding system. Significant interactions were found between SCD genotype and feeding system for six fatty acids: 4:0, 6:0, 8:0, 10:0, 12:0 and t11 18:1. We concluded that the feeding system was the factor that mostly affected milk production and composition; moreover, our results do not confirm what reported in literature as regard the effect of the SCD polymorphism on milk fatty acid composition. The high amount of pasture seemed to have resized the SCD polymorphism effects because of the different fatty acids composition of the diet

Oxidative Status of Goats with Different CSN1S1 Genotypes Fed ad Libitum with Fresh and Dry Forages

Forty late-lactation Girgentana goats were used to study the effect of diets fed ad libitum and αS1-casein (CSN1S1) genotype on redox balance. The goats genotyped at CSN1S1 locus (A/A, A/F) were subjected to four feeding treatments different for percentage inclusion of dry and fresh forage: DAF100 (98% of Dry Alfalfa Forage), DAF65 (65% of Dry Alfalfa Forage), FSF100 (100% of Fresh Sulla Forage) and FSF65 (65% of Fresh Sulla Forage). Blood samples were analyzed for superoxide dismutase (SOD) and glutathione peroxidase (GPX) activity, reactive oxygen metabolites (ROMs), biological antioxidant potential (BAP) and non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), albumin, glucose and cholesterol contents. The oxidative stress index (OSI) was calculated as percentage ratio of ROMs to BAP. Redox balance was improved by Sulla inclusion, as reflected in the lower OSI values found in FSF100 and FSF65 groups. DAF100 group displayed the highest GPX activity, while other groups exhibited the highest SOD activity. Fresh forage diets increased albumin concentration while no effect of tested factors was noted on glucose, NEFA, BHBA and cholesterol contents. The interaction diet × genotype was significant only for GPX activity. GPX and albumin were negatively correlated and were correlated positively and negatively with ROMs, respectively. Diet rather than genotype affects redox balance in dairy goats and a possible role of forage polyphenol compounds on oxidative status needs to be tested in future studies

Effect of the αs1-casein genotype and its interaction with diet degradability on milk production, milk quality, metabolic and endocrinal response of Girgentana goats

We studied interaction between diet degradability and genotype at CSN1S1 locus in lactating goats.•We evaluated productive, metabolic and hormonal response of goats at different αs1-casein genotype.•Little effect of diet degradability and interaction with genotype on production and quality.•Higher milk yield, casein percentage and lower urea in goats with strong alleles at CSN1S1 locus.•Higher tyroid hormones in goats with strong alleles