Browsing ratio, species intake, and milk fatty acid composition of goats foraging on alpine open grassland and grazable forestland

Abstract

Aims of this study were to investigate diet selection of dairy goats foraging on two alpine vegetation types and to assess the related effects on milk fatty acid (FA) composition. Two enclosures laid out on an open grassland (OG) and a grazable forestland (GF) were exploited by 14 Camosciata goats. A commercial concentrate was supplemented during milking. Forty-five plots were randomly selected inside each enclosure and used to assess the species relative abundance (SRA) and phenological stage of plants, as well as goats' preferences (browsing ratio, BR) and intake (SI) for each species.Representative samples of the diet in each enclosure were built up considering the most ingested plant species and plant parts. Feed samples were analyzed for proximate, FA, and phenolic compositions.Milk samples were collected in each enclosure and analyzed for their FA profile. The enclosures showed a similar level of vegetation diversity. If compared to the GF enclosure, the OG one had higher proportion of Poaceae (81.2 vs 44.8% of SRA) and lower proportion of non-legume dicotyledons (14.6 vs 50.7% of SRA). The goats mostly selected eutrophic species in OG and forbs and woody species leaves in GF. The ingested vegetation was almost completely represented by grasses in OG (89.6% of SI), and by similar proportions of grasses and herbs and woody species in GF (54.9 and 45.1% of SI, respectively). The ingested forages from the OG and GF showed a comparable proximate composition; if compared to OG, the GF vegetation type was however richer in α-linolenic acid (ALA) and phenolic compounds (PC). Fatty acid analysis showed that GF milk had higher concentrations of ALA, total omega-3 FA, total trans-octadecadienoic acids, total conjugated linoleic acids, total trans-octadecenoic acids, and a reduced omega-6/omega-3 FA ratio than OG milk.Branched-chain FA were not significantly affected by treatment, suggesting that the activity of ruminal bacteria in the goats was not inhibited by the higher concentration of PC in GF plants. The main reason for the observed improvement of the FA profile in GF milk seems to be attributable to the FA profile rather than the concentration and composition of PC of the ingested plants. The abundance of herbs and woody species in the ingested vegetation was positively associated with the presence of nutritionally desirable FA in goat milk fat.

Effects of season on the quality of Garfagnina goat milk

“…Furthermore, there are different results in the literature about ALA content in goat milk depending chemical parameters of ingested plants (lignine, crude protein, FAs, concentration of ALA on the pasture) (Park et al 2007;Iussig et al 2015). A higher ruminal bypass of dietary ALA has been suggested in goats compared to cow (Cornale et al 2014) and ALA was also found positively correlated with the type and relative abundance of dietary polyphenols (K€ alber et al 2011).…”

Plant species selection by sheep in semi-natural dry grasslands extensively grazed in the south-western Italian Alps

“…number of occurrences per 50 points of vegetation measurements). An SC value of 0.5% was attributed to all occasional species (those not recorded along the transect but within the vegetation plot) (Iussig et al 2015b). …”

Relationship between pre-pubertal nutrition plane with reproduction performance and milk quality in Kurdish female kids

“…A more complete understanding of nutritional regulation of milk secretion would contribute to the feeding and management practices development for altering milk composition and optimizing milk production [8,22]. Thus, one of the main objectives of this study was to determine effects of survey of relationship between pre-pubertal planes of nutrition with milk quality in Kurdish female kids in the west of Iran.…”

“…Most livestock milk produced in the world is processed into cheese, yogurt and other dairy products. For this reason, the relationship between ewe nutrition and milk quality is mainly evaluated in terms of its technological and coagulation properties [7,8]. From lactation studies, the indirect evidence in ewe lambs proposes that before and after the main allometric growth phase, continuous rapid growth may depress mammary development as compared to feeding regimes including minimum one phase of limited feed intake [3,9,10].…”